Towards a general theory of access

Recently published

Abstract: This paper integrates and extends many of the concepts of accessibility deriving from Hansen’s (1959) seminal paper, and develops a theory of access that generalizes from the particular measures of access that have become increasingly common. Access is now measured for a particular place by a particular mode for a particular purpose at a particular time in a particular year. General access is derived as a theoretical ideal that would be measured for all places, all modes, all purposes, at all times, over the lifecycle of a project. It is posited that more general access measures better explain spatial location phenomena.

David Levinson: Transplanted Transportist

I was recently interviewed by Scott Fitzgerald for iMOVE Australia. Copied below

David Levinson is Professor of Transport Engineering, School of Civil engineering at the University of Sydney. Details of his many published articles, and books, can be found on his blog, Transportist.

Good morning, David. Could you tell me a little bit about where you are at the moment and what work you’re doing?

I’m currently at the University of Sydney in the School of Civil Engineering, directing the TransportLab research program. My research reaches into a number of different areas. I have a program working on measuring and advancing the theory of accessibility, how many things you can reach in a given amount of time. For instance, how many jobs you can reach within 30 minutes.

I have students looking at understanding the co-evolution of transport networks and land use over time, using Sydney as a case study. How were trams deployed? Did the trams lead or follow real estate development? And what does that say about transport and land use co-evolution going forward? I’ve done work on this field in the past in other cities, including London and Minneapolis, and since I’m here it was only natural we would look at Sydney.

One student is examining game theory models of lane changing, in particular, can we design socially-beneficial lane changing algorithms that might be used in autonomous vehicles? Having vehicles change lanes when it would save other people time and not change lanes when it would cost other people time.

I also have a student evaluating benefit cost analysis processes. The idea is that while a lot of benefit cost analyses compare alternatives, we don’t know how different are those alternatives? How accurate was the benefit-cost analysis in the first place? And if the accuracy is less than the difference between the alternatives, maybe it wasn’t as important as people think it was.

But if it turns out that the difference in the predicted benefits and costs, compared with what actually happened was relatively small, then benefit-cost analysis is important in determining the best outcome.

Sounds like you’ve got a bit going on and so has your department and students! Moving back in time, what set you on the path of a career in transport?

I grew up in the city of Columbia, Maryland, which is between Baltimore and Washington. Columbia is a planned community. When I was very young, in third grade, we were exposed to the ideas of city planning and I became interested in how to design cities. And how to design efficient cities. Of course, the core of that has to do with how to things relate to each other in space and how are they connected, which gets you into transport.

I was thinking about that career for a long time, and then in middle school, and especially high school, I became interested in computers. That interest saw me start at Georgia Tech as an electrical engineering student. But I decided that wasn’t really as interesting as I might like, so I made the switch to civil engineering, with the idea of getting into transport planning, which I then ultimately did.

My first job out of Georgia Tech was building travel demand models, which combined computers and transport. That was in Montgomery County, Maryland, outside of Washington, DC, and saw me as part of a team building a regional planning model to understand flows between places. This was an area that really grabbed my interest, and I went to graduate school, doing my PhD at Berkeley.

My study was in the area of transport economics, because I thought that the main problem was really the problem of demand. We don’t price streets and roads, especially in the United States, certainly not at what they cost, and so people over-consume roads. This is still true, people over-consume roads in general. The motorways in Australia might be tolled at too high a price here, but the other streets are tolled too low, and the tolls don’t vary by time-of-day.

I also undertook a project evaluating California’s high-speed rail project, which was just an idea at the time. Then I took my first academic permanent position at the University of Minnesota, where I was until 2016 before moving to Sydney in 2017.

In retrospect how did your hometown of Columbia fare in terms of transport planning?

Columbia is, in a sense, too suburban according to current planning theories, and the density is too low to enable effective public transport between places. When it was planned back in the 1960s there was to be a minibus circulator system connecting all the neighbourhoods to the village centres, and then with the Town Center. They had planned a separate right-of-way for this network, but built very little of it, and then abandoned it (some of it was later converted to bike paths). There are suburban buses within Columbia, and a few to Baltimore and Washington, but with really low frequencies.

From a public transport perspective, it didn’t work out really well at all because you need to have a critical mass of demand in order to have public transport work. One of the things about Sydney compared to US cities of a similar size, is that public transport’s really important here. The commute mode share for public transit in Sydney is 21% or so while in similarly sized US cities it is much lower, (well below 10%) and that’s interesting.

So what’s different about Sydney compared to US cities? Obviously it has a higher density of activity. It was built around trains. Although a lot of US cities were built around trains, they then abandoned them, but Sydney did not. Sydney did abandon its trams and replaced them with buses, but buses here still carry a lot of people, whereas in the US buses are seen as a second-class form of transport. Columbia being a third- or fourth-ring suburb didn’t have the population density to be able to support public transport. That resulted in a lot of people using cars and although it has an extensive off-road bike path network, the cycling community’s still small.

From a transport perspective Columbia wasn’t terribly successful in being innovative – the minibus network failed – or being environmentally sound with its reliance on the auto. Though it did get me interested in planning, I wouldn’t want to emulate Columbia. It’s not an icon of good planning in the modern sense of how we would try to design places. It’s a pleasant enough place to live I suppose, but it’s not a place that you can get by easily without a car.

Amidst that answer you mentioned road cost, that invariably the cost of roads is too high or too low. How do you think we get to a Goldilocks level of it being just right?

It’s going to be an iterative process, but I think as automated vehicles and electric vehicles in particular are deployed it will shake up the road funding system. That’s because electric vehicles don’t pay tax on motor fuel use. There ought to be a separate pricing regime for vehicles that don’t use petrol, which would be that they pay per kilometre. They would pay a higher price in peak times and receive a discount in the off-peak, to recover the costs that they impose in terms of congestion, infrastructure wear and tear, and their environmental costs. EVs don’t impose as much environmental damage as internal combustion engine vehicles, but it is not zero.

Autonomous vehicles present an interesting problem as well because today for a car to drive around, the driver is at least spending their own time. They don’t generally drive around circling the block for the hell of it, because they would be wasting their own time and wasting fuel. In an autonomous vehicle, you can avoid parking by ordering the car to just go around and circle the block and not waste your own time doing that. This however wastes everybody else’s time because you’re congesting the roads.

The solution will impose some price for driving. Either it would be illegal to circle the block empty, with an associated high fine associated, or better and simpler, there’s a per kilometre charge for driving in cities. And it’s a higher charge in cities than it is in places with less congestion. That would discourage that kind of behaviour so that instead of driving around using the road space as a way of avoiding paying for parking, people, if they wanted to keep their car near them, would find that paying for parking was the less expensive solution.

I think in a sense these technologies are going to force a change in transport financing one way or another. It would be good to get ahead of it. Western civilisation is not really very good at getting ahead of problems and generally only reacts to crises rather than acting in anticipation. This is unfortunate, but we haven’t really figured out a solution to this political problem. Politicians have to (figuratively) be beaten over the head with a problem until they feel the need to actually resolve it, rather than say, ‘Well this is going to become a problem.’ Road financing problems are not secrets, everyone in the field can see it coming, we should be able to work on a solution ahead of time.

Like this interview? See the rest of our Meet Smart Mobility Experts interviews.

Human nature and all that. Just to veer away from reality for just a second, if you were given a very large budget and no small timeframe in which to do so, what project would you like to see undertaken that would have an appreciable impact on either traffic or however we get around, for ways of improving it?

We could do a lot if we implemented road pricing for instance, right? We could reduce congestion more than with any other technology. And the toll wouldn’t have to be that high because there’s a lot of traffic, even in peak hours that has some flexibility in when it can travel. With a small incentive, a lot of that travel would move to off-peak times when the roads aren’t already saturated. There are research projects that examine this, but what we really need is the political will.

And if you gave me enough money, I could probably buy enough politicians to do that. [That’s sarcasm]. We don’t have the political will to actually implement road pricing – the fact it doesn’t already exist argues it is going to be politically difficult. Politicians aren’t re-elected without understanding what’s politically popular and what’s politically unpopular. And obviously there’s going to be resistance to something like that.

So the next best solution is to phase pricing in over time, with electric vehicles, as more and more EVs get adopted. EV deployment is going to happen with or without government subsidies and policies, though it might be faster with subsidies. EVs are over the long run going to be a better technology than the internal combustion engine. Renewable power prices, battery prices, and the cost of manufacturing EVs continue to fall as EVs are manufactured at larger scale.

This will inevitably happen, but with policy help, and with incentives, it could happen sooner. So that’s one class of things, if we’re talking about pricing.

Getting autonomous vehicles deployed sooner rather than later is something else we could talk about. I think that’s important primarily for safety reasons, although also for capacity reasons on certain facilities.

Indeed. And the second part of the hypothetical is this time, short time limit, small budget, but would make a big change. What would you attack?

The lowest hanging fruit is not particularly technology-related, is how we allocate road space. We give far too much road space to automobiles compared to buses. We should have more bus lanes than we do, given the number of people who use buses. The objective should be moving people not cars. Similarly, we should have many more lanes for bicycles and other micromobility devices so that they can ride at speeds that are faster than walking, so they’re off the footpath, but slower than motorised vehicles. And the bicycle riders would be safer because they’d be in protected lanes with appropriate traffic signal treatments at intersections so that they get priority and their own traffic light.

Reallocating road space is something that we could do now, we don’t need any special technology to do. Other countries do this, but Australia doesn’t. The few local responses to COVID-19 show both its feasibility and benefits, but are insufficient. The United States doesn’t do this on a large scale either.

You mentioned in part of that answer, micromobility and the need to change the makeup of footpath and road space. How do you think, in an ideal situation, space for micromobility should be implemented?

e-bikes in many ways, should sell themselves, but people will only be willing to ride them if they feel safe riding them. And everything that we do in Sydney at least, but in many other Australian cities as well, is very hostile to the cyclist. Cars ride closer than they should, and are aggressive and hostile towards cyclists. There’s an attitude that cyclists are not fully human. There’s an interesting paper on that out of Monash University, that some people dehumanise bicyclists, treat them badly, cut them off, which makes on-road cycling an unsafe and generally unpleasant experience.

And rather than being cyclists themselves some of the time, most people aren’t, most people haven’t ridden bicycles since they were children. Generally there was a lot more bike riding when today’s adults were children than there is today. And what’s the reason for that? And one of the reasons for that is conditions were better 30, 40, 50, 60 years ago to ride bicycles than they are today. There are a number of relevant social trends, there were fewer cars on the road, schools were nearer homes, children were given more independence, there was no internet enticing kids to stay inside, and so on.

So we should promote more bike paths, protected bike lanes and the like, which will make it more pleasant to ride a bicycle. And the more pleasant it is to do something, the more people will do that. But we’re barely moving in the right direction. The City of Sydney has plans to increase the number of bike lanes, but it’s really pretty modest compared to what it ought to be, compared to say, what’s being done in Northern Europe, the UK, and even some US cities like Minneapolis or Portland. If you’re serious about promoting cycling, you have to show a commitment. The commitment is dedicating space so that cyclists aren’t fighting with cars for road space. As with buses, that’s something that we ought to be setting space aside for.

Now how do we get more people to use e-bikes? Well, if the environment for riding is better, people will be more likely to use them. The fines for using them inappropriately are excessively high. So for instance, if you are riding a bicycle without a helmet, there’s a large fine, even if you’re not doing it on the road, even if you’re riding on a bike path, on a trail, at a low speed, there’s still the prospect of a fine for riding without a helmet. Now, there may or may not be a safety benefit to helmets. There’s a large debate in the literature. Clearly if you’re dropped on your head, wearing a helmet is better. But if you’re wearing a helmet, you’re more likely to be dropped on your head, both because cyclists will feel more impervious to harm because they’re wearing the helmets and be more aggressive when riding, but also because cars will feel that people who are wearing helmets can handle a crash more readily and will be more aggressive towards them. And so some car drivers behave badly. Seeing someone in a helmet and thinking, ‘Well, they’re geared up for battle, then they can do battle.’ Rather than seeing them as a person, the helmet encourages drivers to perceive cyclists as an object. An impediment to their road use.

So it’s one thing to say that if you’re riding in traffic, having a helmet might reduce your brain injury risk, which it might. If you’re in a crash it probably does. But if it increases the likelihood of a crash, that’s not as obvious. And since the more punitive helmet laws have been imposed, there have been fewer cyclists in New South Wales than there were. While public policies say they want to increase cycling and active transport, they are also simultaneously working against it.

And I think that’s a problem. If you have to wear a uniform to commute to work, that’s a problem. You should be able to commute to work in regular work clothes, the way people do in other parts of the world. You shouldn’t have to get geared-up and ride at bicycle racing speeds. It’s not the Tour de France, it’s a normal commute trip.

Now, electric scooters have been shown to have high crash risks. And part of that is you have people who are inexperienced riders. Certainly alcohol is related to that, but you also don’t have great facilities for scootering, and if you had bike lanes, the environment in which to use a scooter would be better.

The same applies to skateboards and electric skateboards, which we’re seeing more of on the roads of late. There’s a lot of risk associated with these modes of transport. If they had a separated lane to use, where they were less likely to be hit by an automobile, that might be safer and might encourage more use.

That sounds like it’s a bigger job than you would indicate. How would you do that in a small way, with a small budget?

Well, I don’t think there’s a lot of budget involved. It’s just some paint on the road and putting some concrete barriers up. You can make it as complicated as you want, but if you look at, say, what New York city did under Janette Sadiq Khan, who was the transport commissioner there, they basically did a lot of trials. They closed Broadway to traffic as a trial and they put up some temporary barriers to see how it worked, and it worked fine! They eventually put in more permanent, nicer looking barriers. So put up planters and redirect traffic, take away a lane … we take away lanes for construction all the time. It’s easy to do technically and it’s just a question of prioritisation.

Traffic signal timings are another one. I don’t want to say it’s just flicking a switch in a control centre, but it’s essentially just flicking a switch in a control centre, to give more time for pedestrians to cross the street, to make a traffic signal cycle times shorter so that people don’t have to wait as long at intersections and so that people have more than six seconds to cross the street. We should be counting pedestrians automatically at intersections. This is something that the technology is available to do, it’s not very expensive and that should be figured into the traffic signal timing algorithms, which again, is not technically very difficult to do — other places do it. It’s basically a knowledge transfer problem, and implementing these small changes creates an environment that’s better for pedestrians.

Right now, pedestrians waste about a quarter of their time stopped at traffic signals when they’re going through a city. And compared to a hundred years ago when they didn’t waste any time stopped at traffic signals because there weren’t any, the pedestrian conditions have become significantly worse. We have redesigned our road system to optimise for automobiles and automobile drivers, rather than people on foot. If we want more people to be walking and more people to be on bicycles, we need to optimise the system for people walking and people on bicycles. And this includes road rules, traffic signal timings, allocation of road space, and a number of other matters.

You’re right. All of those things are simply a change in algorithm or clicking a switch. I guess the real stopper is in making a decision.

Yes. Someone has to be decisive and someone has to have the will to do it. And I think no one in power right now has the will to do that. Hopefully soon someone will have both the power and the will to do. But it’s a decision, making conditions better for people on foot, on bike, and in buses may make conditions worse for drivers. Other cities can serve as examples.

Paris, one of the world’s great cities, is looking towards banning automobiles from the entire city centre. This is a major step forward. There are not that many automobiles in the Sydney CBD as it is now, but why is so much space given over to so few automobiles to begin with?

And not just the CBD, it’s everywhere around greater Sydney. Not to say that people can walk from home to work or walk from transit to their destinations everywhere they are, but they can do it in a lot more places than do it now and we should be working towards maximising rather than minimising walking.

Okay, back to you and the work you’ve done now. What projects so far have you been most proud of?

I like the accessibility work I’ve done. Back in the US we built the Accessibility Observatory and we managed to measure accessibility for every one of the more than 11 million census blocks in the United States. Counting how many jobs can you reach in 10, 20, 30, 40, 50, 60 minutes for every point in the United States by auto, by public transport, by walking and by cycling. I think that’s a pretty nice piece of work. And obviously, I had students and researchers working on that. I really like my transport-land use co-evolution work that we’ve done.

I did a case in London when I was on sabbatical there, and followed with work in the Twin Cities to try and understand the causality of this process. Does investment in infrastructure automatically drive land development or does land development automatically attract infrastructure, and which if either of those is the dominant feature? It’s not settled, but I think it’s a really interesting question.

I developed game theory models of congestion pricing, which I think are pretty interesting.

Overall I like my work. I like most of the projects I’ve done. I’ve done a lot of papers so I don’t sit down and rank them in terms of which ones are most interesting and so on. Obviously you’re fonder of some than others. But the areas that I’m still interested in are relate to questions I have worked on previously. I’m still interested in game theory, I’m still interested in land use-transport co-evolution, I’m still interested in accessibility. We’re still doing work in those areas. I think technology deployment is also an interesting question. How quickly do we adopt technologies?

As an example, in what year would there be a 50% market share in new cars for autonomous vehicles? We don’t know the answer to that question, but it’s pretty important, and at some point we will reach that level. But do we reach that level in 2025, 2030, 2040, 2050? There’s a lot of debate about that, but it affects policy now, because if autonomous vehicles provide as much capacity improvement as the proponents claim, then we should stop building roads.

If, as proponents claim, AVs are that much more efficient, if they can follow that much more closely, and adhere to narrower lanes, we can start taking away lanes and unbuilding roads. The sooner it happens, the more we can do that. But while long-run plans that are written by agencies around the world mention or acknowledge that autonomous vehicles are coming, they assume that nothing will change in response to autonomous vehicles. I think that’s a mistake.

Autonomous vehicles will not only be more efficient from a capacity perspective, they might also increase the amount of travel. Because all else equal, if it’s easier to travel, then you’ll travel more. This is something we understand very well conceptually and estimates are we might travel 50% longer if we’re not actually actively driving, and we might send cars on all sorts of new trips.

People today who are unable to drive (e.g. children, the disabled, the elderly, people with suspended licenses) would be able to be passengers in these cars. And if these cars are inexpensive (cars in a world with all AVs can be lighter and smaller, and EVs have fewer mechanical parts and will be simpler to construct) and they don’t require a driver, we’re going to wind up with potentially a lot more travel. This might offset any capacity benefits that we get out of them, which might mean that congestion will go up, which again gets back to the question of how do we manage road space and how do we price roads, which is something we ought to be doing more aggressively already. But it’s going to become more and more apparent as we have these driverless vehicles going around.

But on the other hand, maybe there’s a substitution, maybe people don’t go shopping anymore because we’ve all moved over to a delivery-based economy. And if we can get the logistics for that right, — instead of going out and coming back, then we have a truck that goes down the street once an hour delivering everyone’s latest order or whatever — that should reduce the total amount of travel.

I think there’s a lot about the outcome of these technology trends that are unclear, but the policy-side really should be paying attention, these questions are yet to really enter the realm of public policy or long-term planning. The planning assumes that technology is static and I think that’s something we could do better.

And I guess a lot of the technology, the technologists, are at the moment primarily concerned with market share more than anything else.

Yes, and market share is the first question, but then the implication of the changing technology on behaviour and on how the system is used as an obvious follow-up. There are a number of predictions out there that autonomous vehicles will lead to increased suburbanisation, which is fine potentially, if people in the suburbs don’t have outsized impacts on the environment or whatever. But that does lead to increased travel and is contrary to the regional plans that we have in our cities, which call for a higher concentration into multi-family development.

So I think there’s very much a divergence between where the market is pushing and where the planners want to pull policy. And I’m not sure that that will be easily rectified.

We need everything going in the same direction. You’ve covered a fair bit of ground in your academic career. Is there an area of transport in which you haven’t done any work yet, that interests you and you’d like to do?

There are many things that are interesting, it’s just a question of time. And I’m a professor, I can work on whatever I want to work on really. So I don’t know that there’s anything that I’d want to work on that is more interesting to me than what I am working on, otherwise I would already be working on it.

I think there are a lot of interesting things going on in the Artificial Intelligence space, machine learning, in terms of, making predictions. I think there are interesting things that can be done with modelling. I don’t mean large-scale regional modelling, but just making predictions from big data. We’re doing some work in that area, and it is always exciting to be able to play with new datasets. These are datasets that 10 years ago didn’t exist and now they’re just streaming out all sorts of measures about GPS tracking, smart car datasets, all these kinds of things that we can access now, that just weren’t available before.

So work in that area would be cool. And it’s things I wish I had when I was 22 years old and starting out. Now the data that we have at hand is more than we imagined we could possibly have back in the day.

Okay, closing question. In the short term, next three to five years, what is it that’s heading our way that you’re most excited about?

The increased deployment of AVs and how will that work. And I’d probably put a five-year timeframe on that rather than a three-year timeframe on that. But we already see, for instance, in Chandler, Arizona, Waymo is operating driverless vehicles on relatively low-traffic, suburban streets.

But over time, they’ll get into more and more ambitious use cases and they and other companies are working on city streets in San Francisco and other places that are much more congested and where the driving environment is much more complicated. So I think there’s a lot interesting going on there and we’ll learn a lot about how the technology might work and where the weaknesses are and how we need to regulate the vehicles themselves and how we need to shape the environment to make those vehicles successful in an urban world, along with work on how do we make autonomous vehicles socially responsible.

Right now people are talking about connected vehicles, but connected vehicles have many weaknesses, latency, security risks and so on, associated with them and I think it’s a mistake to be thinking about connected and autonomous vehicles in the same breath, much less the same acronym.

But that’s not to say we can’t make autonomous vehicles that aren’t aware of the world around them, but now they act in a selfish way. Just as individuals route on roads, in a way that minimises their own travel time, autonomous vehicles will, for instance, in the absence of external requirements or incentives, choose lanes that will minimise their own travel time. But if we could get them to behave in a way that is more socially beneficial, that is, only change lanes if they have to or if it reduces congestion for instance, by moving from the more crowded lane to the less crowded lane, we might be able to do something that’s socially beneficial, but something that’s is selfless in a way that the current algorithms are not.

And the question is how do we incentivise the vehicles or the algorithms to do that, and maybe it has to be required or built into the vehicle’s operating system. Or maybe we could use a price signal, if there’s a monetary penalty to changing lanes, then people only change lanes when they have to rather than opportunistically changing lanes continuously. Because lane changing is one of the major causes of shockwaves and congestion and traffic and to the extent that we can reduce that, we can benefit from a traffic perspective.

We are doing some work in that area. And I think there are many opportunities to look not just at the lane-changing behaviour, but also the optimal gap from a car following perspective, when you’re following an autonomous vehicle versus when you’re following a non-autonomous vehicle. Mixed traffic is going to be with us for decades before we get an all-autonomous fleet, so how we handle driving in mixed traffic is still a wide-open question.

More from iMOVE Australia

Sydney trains, buses: Transport use spikes after lockdown amid social distancing fears. | Daily Tele mongers scare.

Georgia Clark at the Daily Telegraph writes: Sydney trains, buses: Transport use spikes after lockdown amid social distancing fears. She says I said :

Another transport expert, Professor David Levinson from the University of Sydney, said the only way to maintain social distancing if demand grows is for the virus to be eradicated – and capacity limits removed.

“If there is no more COVID-19 in NSW, we should not be constrained by social distancing. People concerned can of course wear masks and reduce talking on buses and trains,” he said.

I of course said nothing like the characterisation in the first paragraph. The second is a correct quote. My point, which I thought was clear below, is that if the virus is eradicated, so is the need for social distancing. I.e. there is no need to “maintain” social distancing if there is no virus. The reporter seems quite confused on the issue. She is not alone.

People seem to think social distancing lasts forever. If it does, we are even more screwed as a society than I imagine. The questions and responses below:

1. The NSW Premier says train lines are at capacity. Are you concerned the public transport system may not cope with a potential surge in passengers after COVID-19, potentially leaving some waiting for hours for services?

After COVID-19 means that social distancing rules would be lifted, right? So there should be sufficient capacity, the capacity constraint now is not vehicles, but number of people allowed per vehicle. If the distancing rules are lifted (since there haven’t been any new cases for X weeks), then capacity should be no worse than before COVID-19. I suspect demand will be lower for public transport anyway, as tourists, and people working from home, will both no longer be using transit as much, and some people will have found alternative modes.


2. On that note, are you concerned people may flout social distancing rules on public transport as life returns to normal?
That’s what normal is, the end of social distancing. If social distancing remains, it is not “normal”.

3.  How can we ensure public transport can cope with a surge in usage while ensuring social distancing measures are enforced?

If there is no COVID-19 in the wild in New South Wales, we should not be constrained by social distancing. People concerned can of course wear masks, (and public health officials could require this if they were concerned) and reducing talking on buses and trains reduces potential transmission of many communicable diseases, this is what is done in many Asian cities.

I would add, to date, the evidence that public transport is a major source of transmission of COVID-19 is weak, France and Japan seem to be finding that transit is safe. Should you wear a mask? Sure, if you want to. And please, don’t talk on transit, it’s just better anyway. There are many reasonable adaptations.

Overall, society (and its members, and especially its politicians and press corps) are just too afraid of death. It’s sad when people die. It’s also sad when you try to live risklessly and give up on the reasons for living. It’s sad when authorities use the boogie man of public health risk (which in the long run, undermines people’s trust of the public health system) to shut down public protests (against those very same authorities) about social problems that now seem to have a window of opportunity after decades of social stagnation. It’s even sadder when people’s attempts to live risklessly, cooped up in their houses, increases actual risk, compared to the outdoors. If a vaccine never comes, are we supposed to abandon our cities, our playgrounds, our universities, and more parochially, our public transport systems, for an estimated 0.66% fatality rate among those with the virus? (And a far smaller loss of expected life years, since it disproportionately affects older people.)

Letter to Minneapolis

I lived in Minneapolis from 1999 until I moved to Sydney in 2017. In the last few days, the Minneapolis Police Department is again making the local news in Australia (following on the case of Justine Diamond) with the murder of George Floyd. Thanks to the internet (thanks internet !?) we can now livestream Minneapolis WCCO-TV here, along with the dumpster fire that is Twitter.

When I first took the job, and before moving, the University of Minnesota connected me to a real estate agent (from Edina Real Estate) who showed us around some neighbourhoods he thought we would like (Uptown, Edina). I asked about crime rates. He wouldn’t tell me (I think he implied it was illegal, which it may have been) and said I would need to look that up separately. I asked about some other neighbourhoods, like North Minneapolis, and he, in his Minnesota way, discouraged it. After moving there, I figured out why.

Open street on Minehaha Avenue in happier times. The center of some of the rioting.

We ultimately moved to Prospect Park in Southeast Minneapolis. We would shop and eat out at restaurants in the area around Lake and Hiawatha that was recently torched. We would regularly shop at the Targets on University in St. Paul and Snelling in Roseville that were looted. [Their logo is a target, obviously they were asking for it. And just sitting there, loitering in bad neighborhoods at all times of day and night, imagine what would happen to a person who did that.] [I am assuming looters are not reading this, if they are: looting is bad and does not directly address the problem, and probably undermines the general cause.]

Obviously much of this is crime of opportunity, which can be understood in game theory terms, following on the signalling of collective action among potential rioters, along with the distraction of police. But the core is not looters, the core is a protest against the police, and societal dysfunctions more generally. If society does not treat you with basic respect for your life, liberty, and property, the courtesy should be extended in reverse.

American society is broken. While irrational optimism is important to see our way through the present dilemmas, I believe it is important to recognise the degree of brokenness to do what is necessary. While this might bring us through the Kübler-Ross stages of grief from denial through acceptance, it is only with acceptance and recognition of reality that appropriate change can occur.

By all means vote for the right people, it may be necessary, but do not believe for a moment that it is sufficient. Elected officials, even when the “right people” are in a majority, do not control the Minneapolis Police, or many of the other institutions that are the root of America’s failures.

America, more than perhaps any other country, has become first-rate at admiring readily-solved problems problems [e.g., but this is not a complete list: police violence, gun violence, traffic violence, pollution, disenfranchisement and election malpractice, health insurance, congestion, pandemics, inability to build]. The most basic indicator of social success, life expectancy, is low for a country of its wealth, and falling. This is infuriating.

I say they are readily-solved as developed nations (a list we must sadly now exclude the United States from) have solved them, at least better than the US, and resources are hardly scarce in a country where the average size of a new home is on the order of 3000 square feet and there is a car for every driver, and a military which outspends the next 10 countries combined. This is not to say it is politically easy, otherwise one assumes they would have already been dealt with. But there are no technological barriers, nor lack of good ideas, just an unwillingness to make a hard decision. Politicians should be willing to take votes that will cost them their jobs. They will inevitably find work with the revolving door in industry anyway. There remain other problems (like endemic racism) which are more difficult, which also remain unsolved. America would collectively rather not go through any short run disruption to address even solvable problems with a huge long-run payoff. It suffers from failure of delayed gratification.

I have always thought Minnesota was one of the better governed US states, with a longer time-horizon than most. Minneapolis is very good (for the US, not on a global scale) at building bike lanes and of course it attracts hipsters (and wannabe hipsters) with coffee shops and microbreweries, and the city’s population has risen significantly over the past decade, but it also leads in segregation. All of the progress in bringing people back to the city is for nought when they cannot walk unafraid from violence perpetrated by the police.

This is not new. In recent memory, most notable was the well-known case of Philando Castile, nominally a traffic stop in a local suburb with a trigger happy cop, which inspired numerous peaceful protests closing freeways to temporary inconvenience. There was also Jamar Clark. But before that St. Paul tasered and arrested someone for sitting in the Skyway waiting to pick up his child.

The earth will continue to spin on its axis. Life will find a way. Civilization on the other hand is not nearly so robust. Nominally civilized Europe fell into how many wars last century? It’s not beyond repair, but every moment it remains unrepaired it gets harder. When in a hole the first step is to stop digging. Whether it gets fixed or not is a collective decision and I wouldn’t bet money on it.

“Look for the helpers.” Mr. Rogers said. The helpers are supposed to be the government, which includes the police. That’s what they teach in elementary school. They are not. No amount of policy change will should ever convince us they should be trusted. Their very position, arrogating to themselves a monopoly on the use of violence is perhaps necessary for the avoidance of anarchy, but not without questioning. Of course one must deal subserviently with any organization like the police that has more weaponry than you do. But that doesn’t mean you trust them.

There is an institutional problem that multiple weak mayors have been unable or unwilling to solve. Institutions only work with the consent of the governed. Removing and replacing a police force, especially one the size of Minneapolis is difficult, but not impossible. However with both the murder of residents they are charged with serving and their failure to maintain order in the aftermath of their own misdeeds, they have demonstrated unfitness for purpose. This is not a few bad apples, it is systematic. Fewer than 10% of officers live in the city. It would be easy enough to insist it be 100% and shed many officers voluntarily.

In contrast, while police in many other countries are overly militarized, they retain the confidence of their citizens. Our encounters with the local (New South Wales) police here have been professional as they investigated 1 break-in and theft (and recovered a laptop) and 1 attempted, including taking fingerprints, something Minneapolis could never be bothered to do when we had break-ins there. Notably the police are state rather than locally run. None of this is to say there are no problems: police brutality exists in Australia.

Disband the Minneapolis Police. Bring in temporary outside security forces with clear directives if necessary. Start over. That is what the protests are telling you. Listen to your residents, you govern with their consent.


Although this is not the general point, a modern banking system may have averted the whole problem, which reportedly started with questions about the legitimacy of George Floyd’s cash payment, resulting in the police being called (4 cops for a fake $20 seems excessive in normal circumstances), rather than the use of readily verified electronic debit transaction. It was startling returning to the US in January on the lack of universality of debit payments and the use of signatures in so many places.

Transportist: June 2020

Welcome to the latest issue of The Transportist, especially to our new readers. As always you can follow along at the  transportist.org or on Twitter. The next issue of the Transportist will be August, as July will be reserved for the TransportLab newsletter.

Urban riots in response to police murders [tears for my old hometown Minneapolis, the riots were a few miles from our house, and we sometimes went to those shops] moves into the top spot of the armageddon-of-the-month rankings, as Covid-19 fades from attention, because people got bored.

When will Tesla Full Self Drive be functional?

  • End of 2020 0%
  • End of 2021 3.9%
  • End of 2025 20.9%
  • Never 75.2%

I interpret this to be when will Tesla Autopilot be “Level 4” autonomous on a large share of roads, with drivers not needing to touch the wheel or pedals for most trips. This poll comes with a sample size of 153 Twitter people, most of whom have some transport knowledge. The respondents are very skeptical of Elon Musk. Now much of this is probably deserved with Hyperloop and the Boring Company and his general antics, but on the other hand, Tesla Autopilot already exists and works reasonably well on freeways (death rates are probably lower than humans, though this is debated) and they have been testing on arterials for over 4 years, and it’s not like he is the programmer. 

I did a similar poll of GM’s Ultracruise (Supercruise for freeways plus new autonomous/driver assist features for city streets, similar tech to Tesla FSD without the hype), though with a smaller and non-identical sample. People trust GM more than Tesla, but remain skeptical. 

GM Ultracruise will be functional in at least one model by: 

  • End of 2020 3.4%
  • End of 2021 7.2%
  • End of 2025 20.7%
  • Never 58.6%

I’m at 2021 on both of these.

Recall Notice: Severe acute respiratory syndrome coronavirus 2. The Huanan Seafood Market would like to recall “Severe acute respiratory syndrome coronavirus 2”. It has severe side-effects and should not be consumed. A replacement virus is available with exchange at site of purchase.

Universities, which are financially strapped at the moment, could save money by canceling subscriptions to expensive journals. We can get that knowledge in other ways now. 

In contrast, their current plans are highly uncertain.

Research 

Transportist Blog

Transport Findings

News & Opinion

Books

A Review of Game Theory Models of Lane Changing

Recently published:

Driver lane-changing behaviours have a significant impact on the safety and the capacity of the vehicle-based traffic system. Therefore, modeling lane-changing ma- neuvers has become an essential component of driving behaviour analysis. Among microscopic LC models, game theory-based lane-changing models highlight the inter- action of drivers, which reveal a more realistic image of driving behaviours compared to other classic models. However, the potential of game theory to describe the hu- man driver’s lane-changing strategies is currently under-estimated. This paper aims to review the recent development of game-theoretic models that are classified ac- cording to their different methodologies and features. They are designed for both human-driven and autonomous vehicles, and we hope they can find applications in future AV industries.

classGT

Virus loading as a queue

Science could use more interdisciplinarity. Models from disparate disciplines can be transferred and may give insights, at least by analogy, if not direct mathematical application.

Queueing models are common in transport. A queue forms when the inputs exceed the outputs. For instance think of cars at a bottleneck. Imagine cars arrive at 1 per second, but can be served (move through the bottleneck) at 2 per second, in this case there is no queue. Instead imagine cars arrive at 4 per second, but can be served at 2 per second, here the queue grows in length by 2 cars per second. At the end of an hour, the queue is 7200 cars in length.

This same logic could be applied to viruses, though the math is a bit more complicated since viruses and antibodies have doubling rates rather than arrival and server capacity or departure rates. Your body is exposed to a single copy of a virus, it doubles at some rate and causes damage as discussed below. If all is going well, your body produces antibodies [and cytotoxic T lymphocytes (CTLs)] in response, which serve (kill) the virus and its production system.

Lev Osherovich, biologist friend of mine, notes:

Covid-19 virus. Source wikipedia
Covid-19 virus. Source wikipedia

There’s a lot more to a successful immune response against SARS-CoV-2 than just antibody production — for example, there is a strong component of cellular (cytotoxic) immunity that goes after infected cells before they can churn out more virus. However, it’s a matter of time and chance for the immune system to figure out how to make the right combination of antibodies and cytotoxic T lymphocytes (CTLs) that can quell the virus — in some patients that happens quickly, before the virus penetrates deep into the lungs to cause acute respiratory distress syndrome, but in many patients (particularlly elderly and immunocompromised) the virus gets there first. In general, once an effective immune response is launched, the immune system can rapidly scale up production of the right plasma cells (antibody factories) and CTLs — the bottleneck is in finding a winning combination through random chance. We hope (but are not certain) that once an effective immune response occurs, it will rapidly clear the virus and will prevent re-infection — at its best, anti-viral immunity is an all-or-nothing process.

 

Antibody and CTL production varies by individual, older individuals and those who are immune-compromised may produce less effectively than young adults.

For someone newly exposed, the virus has a head start, so the antibody and CTL doubling rate has to be shorter (it doubles more quickly) to catch up. If the virus lead is too great, your body is overwhelmed not just by viremia (high viral titres) but cytokine release syndrome (CRS) — “when large numbers of white blood cells are activated and release inflammatory cytokines, which in turn activate yet more white blood cells.” There is a maximum queue length (number of un-dealt with viruses and cytokenes ) in the body, at which point you die. As you approach this maximum, you get sicker.

Lev writes:

The typical cause of death is not viremia (high viral titres) but cytokine release syndrome (CRS), an inflammatory over-reaction triggered by too much virus in the lung but exacerbated by pre-exisiting conditions and susceptibilitiies. There are evidently many patients who experience high viral titre (and are very ill) but do not progress to CRS, ARDS and death, and likewise there are some patients who progress rapidly to CRS and death without high viral titres. In the context of your queuing model, in the some cases the virus (or the immune system) jumps the queue and kills the patient. While presumably having high viral titre increases the odds of such an event, there seems to be some element of bad luck as well as predisposition.

 

In the figure below, viruses start doubling at time 1 (first exposure), while antibodies (and CTLs) don’t start until time 16, but they double twice as fast. By time period 28, they start to noticeably slow the growth of viruses, and due to the power of compound interest, effectively destroy them by time period 30. Assuming the patient can survive a load of 10 million viruses in their body, everything is fine. But there is a threshold, and if the antibodies aren’t fast enough (start too late, double too slowly), the patient won’t make it.

Virus input (demand or arrival rate) varies by location, e.g. cruise ships or nursing homes with recirculated air and exposure to many other infected people increases loading, so it is not a single virus that infects the subject, but many, thereby giving the virus an even longer head start, and making the job of eradication that much more difficult.

Antibody production (capacity) can be stimulated with vaccines or with previous exposure.

Race

While obviously the body is more complex than a queueing model, so is traffic. The aim of a model is to give us a way of thinking, which might suggest solutions (reducing viral intake (defense), speeding response (offense), and so on).

Beautiful Access

What is beauty? A dictionary tells us:

n.      The quality that gives pleasure to the mind or senses and is associated with such properties as harmony of form or color, excellence of artistry, truthfulness, and originality.

— From The American Heritage Dictionary of the English Language, 4th Edition. 

The internet’s best website, the Online Etymology Dictionary says the word comes from Latin bellus “pretty, handsome, charming”

Beauty creates happiness, joy, or pleasure Though obviously these words are often used synonymously, they are not always synonyms. Pleasure is the opposite of pain, and is momentary, intense, but fleeting. Happiness, though more sustained than pleasure, remains a more transient sensation than joy. Children bring you joy, but less so happiness.

timelessSo what business does an engineer have in even examining the idea of beauty with something as abstract and technical as the notion of access. Beauty is not just for the traditional artsy-fartsy aesthetes — scientists, mathematicians, and engineers have their own notions of beauty and elegance.

Math and the physical sciences can have beauty.  Beauty has a mathematical sense of nice (a nice result vs. an elegant result).

In physics: 

[B]eauty is a guide .. symmetry, simplicity and something called naturalness are often sought. — Steve Crandall

In math:

`[E]legant’ = “that proof is a lot more efficient than I would’ve thought”  while `beautiful’ = “that method of proof is genuinely enlightening and makes things possible I wouldn’t have thought were doable.” — Haggai Elitzur

In short, in theories, beauty and efficiency are complements. Things that are inefficient are far from beautiful. Is the same true in our perceptions of the physical world? Most of us agree on the many environments that bring us happiness, and others that bring us the opposite.

There are clues. One has to do with how human senses evolved to absorb information. Not too much sensory input, nor too little, but the amount the human mind has adapted to. This of course varies per person. For instance, autism may be a result of too much sensory sensitivity, an over-wired brain.

This perhaps explains why much of nature is often thought beautiful, humans evolved in a natural environment, and have acclimatised to environments with certain levels of complexity. Yet we have repulsion at certain types of bugs and snakes and so on, which might have been considered predators. We adapted to prefer certain environments rather than others. The built environment, which we have lived with for a much shorter period of time, is far more contentious. It is a product of creationism, rather than evolution, and the parts of the built environment which we adjudge the least beautiful are often the most recent (yesterday’s mistakes are often destroyed, but perhaps yesterday also made fewer mistakes).

The mythological figure Adonis was a beautiful male, his beauty gave him pick of the Greek Goddesses. So, in theory, the beauty to him conferred a biological advantage, increased reproduction with fitter females, though he is only reported to have had two offspring (Golgos and Beroe). But even more than private benefits, Adonis beauty may have also given pleasure to those he chose not to bed himself, who could imagine him while loving those not quite as attractive. Beauty produces benefits for others that cannot be fully capitalized by the beautiful, in an economic sense, beauty creates positive externalities.

In selecting a mate, beauty remains an important factor, the ‘beautiful people’ congregate amongst themselves, and assortative mating indicates that a ’10’ will more likely marry a ‘9’ or a ’10’ than a ‘7’ or an ‘8’, much less a ‘1’ or ‘2’ (where we rate people by decile, so a 10 is among those who would be in the top 10th percentile of attractiveness as ranked by people from their culture, and a 9 is in the top 20th percentile, and so on, so that a 1 is among the least attractive 10 percent.) Now beauty isn’t everything, and a beautiful person may choose to trade beauty in a partner for smarts or bravery or strength, none of which correlate perfectly, with the hope that beautiful but not so smart plus smart but not quite as beautiful couple produces children who are both beautiful and smart, rather than not so smart and not quite beautiful. In a simplistic Mendelian breeding strategy, this might happen 1 in 4 times, but in practice there may be other selection processes going on giving the favourable outcome a better than 1 in 4 shot.

We are all familiar with the concept of beauty when applied to other humans, whether we like it or not, and can see daily the media and marketers selling us on a culturally if not biologically preferred definition of idealized appearance.

We have similar ideas when it comes to place. The wealthiest people use their resources to live in some of the most beautiful environments, because they can, subject to other constraints like accessibility (and inaccessibility). There is sorting among the well-to-do and housing. (If there weren’t what would be the point of being rich?) But since beauty and efficiency are complements, there is no reason why we cannot all have beautiful environments, we just need to organise our resources somewhat better.

Some environments bring us happiness and joy, they are places we want to spend our time, and other environments bring us down.

In Battle for the Life and Beauty of the Earth, architect Christopher Alexander makes a case for hand-made and human-scale rather than automated and massive buildings and places. That sounds an expensive approach. Is there any fundamental reason why the development system of today cannot produce beauty and efficient, durable construction that scales for the masses? The terrace houses  of Australia are lovely in the aggregate, and also relatively mass produced in the day.

We might alternatively pose this problem as one of `Form vs. function’, for which the architects have had a famous dialog. Louis Sullivan, to whom Frank Lloyd Wright apprenticed, wrote:

Whether it be the sweeping eagle in his flight, or the open apple-blossom, the toiling work-horse, the blithe swan, the branching oak, the winding stream at its base, the drifting clouds, over all the coursing sun, form ever follows function and this is the law. Where function does not change, form does not change. The granite rocks, the ever-brooding hills, remain for ages; the lightning lives, comes into shape, and dies, in a twinkling. — Louis Sullivan

This harkens back to Keats:

Beauty is truth, truth beauty, that is all / Ye know on earth, and all ye need to know — John Keats (1820) Ode on a Grecian Urn

and `truth and beauty’, as a building where the form is pre-eminent over the function is in a sense fakery, it is untrue to its purpose.

Which argues that needless adornments are indeed needless. But then what is needless? Sexual selection has produced peacock’s tail, widely perceived as beautiful by humans, and which is locally optimal for the individual peacock (helping him strut his stuff before the peahens), but likely dysfunctional in the longer term group struggle of peacocks against other species seeking to occupy their niche. This is a social dilemma for peacock society, so much resource is spent on adornment, that the species loses out as a whole. 

But is the opposite of needless adornment, minimalism, beautiful? This is not a universally accepted notion. Consider the classic debate:

Less is More — Mies van der Rohe

vs.

Less is a Bore — Robert Venturi

Having high quality designs that people actually want to be around is something we as a society are perfectly capable of doing, if we actually valued it. These designs are neither simple ornament nor stripped bare minimal cost structures. They need not be constrained to a particular style from a particular era, though they should be compatible with the climate and complement neighbouring structures.

Consider infrastructure. Normally not considered at all, but if so, it would generally be thought to be purely functional. Yet London’s Underground is nothing if not stylish. As the first Underground rail system, it was at the forefront of transport technology from its grand opening in 1863. From 1908 forward, it has pushed forward the state of the art in transit system design. The head of the London Transit, Frank Pick, had a keen design sense, and hired Edward Johnston to give London the consistent, and by most accounts excellent, iconic look and feel it has today.

The logo of the London Underground, the bar-and-circle symbol officially called a `Roundel’, evolved over time to its familiar form, by the 1920s. It was so successful that it has been adopted by other rail systems, notably older urban stations in the Sydney Trains system. It has also been adapted by for my book the  30-Minute City, where an early version of this blog post was considered as a chapter.

The London Underground has not only given us a logo, it also presents Maps, Posters, Fonts, Stations, and Vehicles that have thoughtfully considered aesthetics as well as efficiency in their physical expression. While more expensive in the short run to create, standards and design require some investment, they are also more effective in communicating the aims and intent of the organisation.

Kevin Lynch gave us the `View from the Road’, and our perception via windshield inspection differs from that on foot. We should also consider the view from the bus, the view from the train, the view at the train station, and the view from the bike.

Beauty changes both how much time you perceive, but also the quality of that time, and how much you would pay to experience or avoid it. I may pay to avoid an ugly route, I may pay to traverse a beautiful one. We know from route choice experiments, people say they prefer the more attractive route, even if slower. In short, the journey is at least part of the reward.

Access has focused on objectively represented time, though we have talked about perceived or reported time, from time-to-time. We have yet to fully address quality of time, or willingness to endure particular environments.

We can easily treat this mathematically. The more difficult question is actually assessing those environments, translating them into something quantifiable, like we do for money or time, so that aesthetic judgments can be rendered objectively, rather than arbitrarily. We know people prefer trees at bus stops, for instance.

Do we want access to beauty, or beautiful access — the latter referring to beauty permeating our lives? Obviously both, but the beautiful access is much more significant, because we experience it so much more often. Museums are largely inaccessible storehouses of beauty. While being able to visit a scenic vista or museum is better than the alternative of not being able to do so, having beauty around us on our ways about our neighbourhood and community, and not merely a few selected beautiful objects, but a pleasing amalgam of all of the natural and built environment, will, I argue, make us collectively happier. If we can make travel paths more beautiful, people will enjoy them more, and 30 minutes will feel like 20.

Thus, beauty, which should complement efficiency rather than compete with it, must have value in the public sphere, just as it does in the private. Beautiful neighbourhoods are more expensive, and thus pay more taxes — people pay to enjoy the beauty provided by the community, that is their neighbours private goods: their homes and yards. And we can have it for the low, low price of some thought and consideration — at a minimum, requiring any visible changes to the built environment make it more beautiful, not less — but setting a bar higher than that, say it must also be better than, say, two-thirds of existing structures in the community.

We can actually quantify this.

Would you be willing to endure 1 minute of ugly for 5 minutes of beauty every day, for the rest of your life. How about 2 minutes, 5 minutes, 10 minutes? That’s hard to assess.

Instead,  for instance, imagine a rule whereby the project regulator conducts a preference survey among a reasonable large jury drawn from the community,  when shown two sets of renderings, the proposal embedded in the surrounding buildings and environment and a series of random similarly-sized structures serving a similar function (houses vs. houses, apartment building vs. apartment building, store vs. store, warehouse vs. warehouse, office vs. office, street vs. street, station vs. station,  drawn from the same community rendered in that same location, the proposed structure must be preferred (supported by more than half the respondents) over more than two-thirds of the structures. Obviously neighbours with a vested interest would be in a separate sample from the general community. These surveys are relatively inexpensive to conduct compared with the costs of large projects.

There is always the risk that the community has terrible taste, but we are not asking them to design the structure, just identify whether it improves or worsens the community. I think the public is capable of doing that, and the bias towards aesthetic conservatism is wise. Perhaps it risks the unusual being downvoted, missing some successful starchitecture like the Sydney Opera House, but it also perhaps filters the high-concept, overly expensive misbegotten architecture which jars with the local neighbourhood. Any system risks being gamed or corrupted, but would it be worse than what we have now? It’s worth testing.

While no particular measure of beauty is complete, and at least some beauty is in the eye of the beholder,  having no measure or standard at all implicitly values beauty at nothing.

 

Estimating the Social Gap with a Game Theory Model of Lane Changing

Recent paper:

Changing lanes is a commonly-used technique for drivers to either overtake slow-moving cars or enter/exit highway ramps. Optional lane changes may save drivers travel time but increase the risk of collision with others. Drivers make such decisions based on experience and emotion rather than analysis, and thus may fail to select the best solution while in a dynamic state of flux. Unlike human drivers, autonomous vehicles can systematically analyze their surroundings and make real-time decisions accordingly. This paper develops a game theory-based lane-changing model by comparing two types of optimization methods. To realize our expectations, we need to first investigate the payoff function of drivers in discretionary lane-changing maneuvers and then quantify it in an equation of costs that trades-off safety and time-saving. After the evaluation for each alternative strategy combination, the results show that there exists a social gap in the discretionary lane-changing game. To deal with that problem, we provide some suggestions for future policy as well as autonomous vehicle controller designs, offering solutions to reduce the impact of disturbances and crashes caused by inappropriate lane changes, and also, inspire further research about more complex cases.

 

multi_speed