How more development can lead to less travel: Examples

Balancing housing and jobs, so that they are located near each other, logically reduces travel compared to a situation where those same jobs are far apart. This has long been understood in the transport planning community (see e.g. Cervero 1989, or my 1998 paper), but is not well grasped among the general public.

However, moving a fixed number of things around is not how cities actually grow. Telling place A you taking away their employment is controversial. More generally new things are added.

Development in Mascot. Photo by author.
Development in Mascot. Photo by author.

It is commonly asserted that more development adds to congestion. And often this is true. But not always, it depends on the type of development. More housing in a housing-rich and job-poor area will result in more total travel. More employment in a job-rich, housing poor area will do similarly. More housing in a job-rich area, and more jobs in a housing-rich area can actually reduce travel.

For our baseline case, imagine a city with two precincts separated by 2 km.

Precinct A: 1000 Jobs, 0 Resident Workers

Precinct B: 0 Jobs, 1000 Resident Workers.

The one-way (morning commute) trip table looks like:

Jobs 1000 0
Workers A B
0 A 0 0
1000 B 1000 0

Total daily travel to work is 2000 person km per day. (Everyone commutes from B to A). Travel on Link BA is 1000 at 2 km per trip, or 2000 person km traveled. (This just analyzes one-way trips. Round trip commutes would double this.)

Case 1. 

There is a proposal to intensify development in Precincts A and B, so each is more locally balanced.

Precinct A: 1000 Jobs, 500 Resident Workers

Precinct B: 500 Jobs, 1000 Resident Workers.

The new one-way (morning commute) trip table looks like (rounded):

Jobs 1000 500
Workers A B
500 A 498 2
1000 B 503 497
  • assuming 0.5 km intrazonal travel distance, using a doubly-constrained gravity model with a d_{ij}(-2) impedance function.

The Daily Travel on links:

AB = 2 @ 2 km

BA = 503 @ 2 km

within A = 498 @ 0.5 km (walking)

within B = 497 @ 0.5 km

TOTAL = 1507 pkt.

This is considerably less than the baseline case as many more travelers can reach their destinations locally. While there is still some commuting, it is far less than before.

Case 2.

There is a proposal to build a locally-balanced Precinct C halfway between Precincts A and B.

Precinct C has 500 Jobs and 500 Workers

The new one-way (morning commute) trip table looks like:

Jobs 1000 0 500
Workers A B C
0 A 0 0 0
1000 B 666.666667 0 333.333333
500 C 333.333333 0 166.666667
  • assuming 0.5 km intrazonal travel distance, using a doubly-constrained gravity model with a d_{ij}(-2) impedance function.

The Daily Travel on links:

BC = BA + BC = 1000 @ 1 km

CA = BA + CA = 1000 @ 1 km

within C = 166 trips @ 0.5 km

TOTAL = 2083 pkt.

In this example, the total person kilometers traveled (pkt) on the links connecting inter-city precincts is essentially identical to the base case, despite adding 500 residents and 500 workers halfway between each. There are an additional 167 pkt daily on the intrazonal market (within C), which is likely walking.

The total one-way commute travel per person however drops, from 2 km/person per day to about 1.38 km/person per day. The average trip length is reduced. The experienced travel is thus about one-third lower.

Case 3

Building on Case 1, completely balancing A and B (so each has 1000 jobs and 1000 workers) reduces one-way commutes further (to 1176 pkt)

The new one-way (morning commute) trip table looks like (rounded):

Jobs 1000 1000
Workers A B
1000 A 941 59
1000 B 59 941
  • assuming 0.5 km intrazonal travel distance, using a doubly-constrained gravity model with a d_{ij}(-2) impedance function.

So, it should be clear from this example that adding development can actually reduce total travel, if it is the right kind of development in the right places.

A Political Economy of Access: Infrastructure, Networks, Cities, and Institutions by David M. Levinson and David A. King
A Political Economy of Access: Infrastructure, Networks, Cities, and Institutions by David M. Levinson and David A. King

The End of Traffic and the Future of Access (Free)

The End of Traffic and the Future of Access: A Roadmap to the New Transport Landscape. By David M. Levinson and Kevin J. Krizek.
The End of Traffic and the Future of Access: A Roadmap to the New Transport Landscape. By David M. Levinson and Kevin J. Krizek.

We are pleased to announced that you can now download a PDF of The End of Traffic and the Future of Access: A Roadmap to the New Transport Landscape from the University of Sydney eScholarship Repository (Free).

Title: The End of Traffic and the Future of Access: A Roadmap to the New Transport Landscape
Authors: Levinson, David
Krizek, Kevin J.
Keywords: transport
automated vehicles
electrification
futurism
sharing economy
pricing
Issue Date: Oct-2017
Publisher: Network Design Lab
Citation: Levinson, D. M., & Krizek, K. J. (2015). The End of Traffic & the Future of Transport. Network Design Lab.
Abstract: In most industrialized countries, car travel per person has peaked and the automobile regime is showing considering signs of instability. As cities across the globe venture to find the best ways to allow people to get around amidst technological and other changes, many forces are taking hold — all of which suggest a new transport landscape. Our roadmap describes why this landscape is taking shape and prescribes policies informed by contextual awareness, clear thinking, and flexibility.
URI: http://hdl.handle.net/2123/18972

If you want other versions, please go here.

An argument in favour of streetcars

I am a noted streetcar skeptic. I have written blog posts about their issues. As an objective analyst, I will however admit an advantage streetcars or trams have over buses.

This is not the ‘permanence’ justification that is often heard and easily disproved (i.e. where are they now if they were so permanent?). But it is related, once laid down, tracks are harder to move than buses, and tracks are more expensive, so it is harder to make routes circuitous. Many bus routes look like they were designed by drunk transit planners. One local bus the 370, which runs near my office and my home is so circuitous it is faster to walk even ignoring schedule delay. (It is not quite faster to walk end-to-end though, walking time is 2:30 vs. 1:14 on the bus, so the effective bus speed, assuming schedule compliance, is about 9.6 km/h vs. 4.8 km/h walking.) I have written about this before in Minneapolis, (and nearby Rosedale) and circuity is hardly an unknown problem.

370 Bus Route on Google Maps
370 Bus Route on Google Maps

Now there are undoubtedly reasons for every indirect deviation that diverts buses from the straight and narrow. However, every circuitous zig also loses passengers, and bus routes in the US are much more circuitous than travel by road. Serve this building, serve that one, cover this street, reduce pedestrian walking time.

In contrast, trams in practice are much more straight-laced, paragons of transit routing virtue. The historic Sydney Tram Map, as this map in wikipedia shows, gives a sense of routes that were pretty much as direct as possible.

Eastern_trams-1.png

Now it can be argued this particular bus provides and east-west service that no tram did, which is true in part. But that doesn’t mean trams could not. It also could be argued that almost no one rides the 370 end-to-end. Though I have not checked the Opal data, this is probably true as well. But a well-structured suburb-to-suburb transit network (my fantasy map is here, Jarrett Walker has done this as well) could avoid this. To be fair as well, the Sydney frequent network is not nearly as circuitous as the 370 bus, which has a roughly 20 minute headway

A Political Economy of Access: Infrastructure, Networks, Cities, and Institutions by David M. Levinson and David A. King
A Political Economy of Access: Infrastructure, Networks, Cities, and Institutions by David M. Levinson and David A. King

The Future of Transport and Access

I had the opportunity to present in Manly earlier today to GPT, an Australian property company,   about The Future of Transport and Access. (I also had the opportunity to ride the Manly Fast Ferry, twice!) Actually, I gave the talk 4 times to 4 different groups, as they had the attendees shop around at the marketplace of ideas (it was a regulated marketplace). They had an artist draw my talk (once), which is below.

FutureOfTransportAndAccess

The full book is available of course at a very reasonable price.

The End of Traffic and the Future of Access: A Roadmap to the New Transport Landscape. By David M. Levinson and Kevin J. Krizek.
The End of Traffic and the Future of Access: A Roadmap to the New Transport Landscape. By David M. Levinson and Kevin J. Krizek.

Road Rent – On the Opportunity Cost of Land Used for Roads

There are a number of ways to view the cost of automobile travel. For instance

This post looks at the idea of road rent. At the margins, what is the value of road space, and how might that cost look on a per vehicle-km traveled basis?

Real Estate

Land has value. Land used as roads has value both as a road and potentially for other uses. What if the value for other uses was higher than that for use as a road?

In Greater Sydney land values range from to $AU210,000 per m² in Barangaroo on Darling Harbour to under $AU1000 per m² in Western Sydney [link].  In Minneapolis, we estimated a few years ago that average assessed land value as $144 per m² for roads and $30 per m² for highways. [Junge, Jason and David Levinson (2013) Property Tax on Privatized Roads. Research in Transportation Business and Management. Volume 7. pp. 35-42.] It seems that assessed value is about 2/3 of market value in Minneapolis.

In some places it is much higher, in some places much lower, the examples used herein are simply an illustration.

The idea is that there is land holder (such as a government land agency) that has to decide whether to allocate land to road uses or for other purposes.

Parking Rent

Consider a typical suburban residential neighborhood with `free’ parking in front of houses. The land is valued at $1,000 per m². Each house requires one parking space out front, and parking is permitted 24 h per day. Conservatively, a car takes 10 m² when parked (the road is the access lane, we consider that separately). It would cost $10,000 for the land owner to purchase the land equivalent of the parked car. The annual rent on that would be $400 (at 4% interest).

In this example $400 is how much the car owner should pay annually  to their municipality for a permit to park their car to cover the cost of land (not the cost of infrastructure, or any other costs of roads and mobility, just the cost of land). This is a bit more than $1/day (more precisely $1.095/day). In more expensive neighborhoods, this would be higher, in less expensive neighborhoods, lower.

For Minneapolis, I have previously estimated about 220,000 on-street spaces. At $400/space per year, this would raise $88,000,000 per year, a not inconsiderable share of the city’s $1.3B annual budget. Instead it is mostly given away free.

Consider the implications if property taxes were reduced by up to $88M in total, and parking permits sold at $400/year (payable monthly with the water and trash bill). People would realize the cost of on-street parking, and there would be less of it, and less vehicle ownership at the margins, and fewer trips by car. Space freed up could be re-allocated.

Alternatively, $400 per year is the value of public subsidy from publicly-owned land to private car owners who get `free’ on-street parking. In short from the car-less to the car owners.

Alternative Uses of Road Space

The economic idea of opportunity cost is important here. Opportunity cost is value of the next best alternative. The next best alternative to road space might be renting it out. So for instance an urban US freeway that destroyed blocks of extant development when it was built has an opportunity cost associated with the value of that real estate.

So the question arises as to what other uses  could be made of the road; for if there were no other uses, you might as well store cars for free. Here are several other uses that could be  considered to replacing a parking lane:

  • Park or parklet,
  • Bike lane,
  • Bus lane,
  • Paid parking, via meters,
  • Shared car parking (rented to the car sharing company),
  • Shared bike parking (rented to the station-based or dockless bike sharing company),
  • Taxi or ride-hailing stand,
  • Bus stop,
  • Shared scooter parking (rented to dockless scooter sharing company),
  • Food truck or ice cream vendor,
  • Road for moving motor vehicles (a parking lane could be another moving lane),
  • Sold off for development.

The last item deserves some discussion. Consider that our road with two parking lanes (one on each side) is maybe 10 or 12m wide (~32 to 40ft). This is wider than some houses are long. The city could in principle retain the sidewalks and sell off the roadbed for townhouses or single family homes. Given the houses are already serviced by alleys, and so long as not all roads were sold off, some roads could be. An illustration of this is the Milwaukee Avenue in Seward in Minneapolis, as shown in the figure. You will see there is no paved street in front of the houses. This could be tightened up further or realigned should there be demand.

Milwaukee Avenue, Seward. Source: http://maha2014.dreamhosters.com/history
Milwaukee Avenue, Seward. Source: http://maha2014.dreamhosters.com/history

This is not appropriate for every street. However, (1) there are places this can be done, where roads are in excess and housing scarce, and (2) this illustrates that land currently used as asphalt to store and move cars has value, and that houses have value even in the absence of streets for cars in the front.

There are always excuses — utilities may need to be relocated, fire trucks would need to go slower down narrower sidewalks. But these excuses can be overcome, there are numerous examples of narrow paths that function as roads.

Driving Rent 

Note: 1 are = 100 m² and 1 hectare  (ha) = 10,000 m²

Typically each car is in use 1 – 1.5 hours per day, and parked for the remainder. In the previous section, we considered parking, the `remainder,’ in this section we look at the time in motion.

When in use, the car is occupying not simply its area (the 10m² = 2m x 5m), but also is preventing the use of other space around it. On a freeway with a capacity of 1800 vehicles per hour traveling at a freeflow speed of 100 km/h, (i.e. just before the speed and flow drop due to congestion sets in) there is a critical density of 18 vehicles/km.

18 vehicles per km is 55.5 meters per vehicle. Lane width is 3.65 meters, so the area occupied is 202 m². Let’s round to 200 m². Each moment  a car is in use, it is using 200 m², on which it should pay rent. So for an hour a day, this is 720,000 m² s or 72 ha s.  (The meter-squared by second (or hectare second) is a new unit of measurement (a time-volume) that needs a catchier name).

It is the density that is the relevant number here, since vehicles are occupying space that we are charging rent for in this thought experiment. Though they are moving, and so the space they are occupying moves with them, there is always some space being occupied for the duration of their travel. Each of those vehicles per hour is occupying a moving window of space.

Roads are a Time Share

When roads are less congested, cars are consuming more space per vehicle. So uncongested urban are much more expensive per traveler than congested rural roads.  When traffic breaks down, they are consuming less space, but presumably are occupying that space for more time, since they are going slower. Induced demand [link] and travel time budgets [link] negate that to a significant extent.

B-UkEPIIUAAIhX9
Illustration of space occupied by cars. Note that most cars do not have 2 occupants. This particular layout is, surprisingly, in somewhat congested conditions. Cars often take up more space at higher speeds. Screen still from a 2002 Saturn car company TV commercial. Image source:  The San Francisco ad agency Goodby, Silverstein & Partners.  Article: Raine, George ‘Goodby, Silverstein agency celebrates 25 years’ SF Chronicle.

George Raine https://www.sfgate.com/business/article/Goodby-Silverstein-agency-celebrates-25-years-3285120.php#photo-2434077

In this example, the hourly rent on 200 m² is what we are interested in. Though cars move, over the course of 1 hour of travel in these conditions, they are claiming that much space. The specific space they are claiming moves with the vehicles, but this all balances out as other cars claim the space they vacated.

Empty roads still have to be paid for, and paid for by actual road users. Even when a road is not being used, it is available to be used. Travelers have the option of traveling. Pavements cannot be easily be rolled up and allocated to other purposes on the fly, particularly purposes like buildings. (Roads can occasionally be closed for special events, but this is rare during business hours.)

 

Example

Consider a car trip that uses 3 roads:

  • Road section 1 (suburban residential): l=5 km, w=3.65, v=30 km/h, q=1000 veh/h, k=33.33 veh/km, AADT=10,000 vehicles/day/lane, p= $1000/m².
  • Road section 2 (motorway): l=10 km, w=3.65, v= 100 km/h, q=2000 veh/h, k= 20 veh/km, AADT = 20,000 vehicles/day/lane, p= $5000/m².
  • Road section 3 (downtown): l= 1 km, w=3.65,  v=40 km/h, q=1600, k =40 veh/km , AADT=16,000 vehicles/day/lane, p= $10000/m².

where: l = length (km), w= lane width (m), v=velocity (km/h), q=flow (veh/h), k=density (veh/km), AADT = Average Annual Daily Traffic, p= land value ($/m²), i=interest rate = 0.04, r= land rent ($/year/m²), d = days/year

Consider each road section to be a homogenous pipeline. (With heterogenous traffic, this is obviously far more complicated, and we would make use of the q, k, and v variables to compute an area-time.)

The annual rent (R) for  each road section is the R=p*i*l*w

  • Road 1: R=$1,000/m² y * 0.04 * 5,000 m * 3.65 m  = $730,000/y
  • Road 2: R=$5,000/m² y * 0.04 * 10,000 m * 3.65 m = $7,300,000/y
  • Road 3: R=$10,000/m² y * 0.04 * 1,000 m * 3.65 m = $1,460,000/y

This annual rent is paid by the road agency to the land owner for the use of land as a road. The road agency then wants to recover this cost from its customers, the travelers.

The question of how to allocate always has some subjectiveness to it. Another way of thinking about it is based on elasticity of demand. Peak hour work trips are perhaps the least elastic (least sensitive to price), and so from an economic efficiency perspective should bear the greater cost.

In this example, we take a simpler tack.

The allocation is R/AADT to get cost per year per daily tripmaker, and divide by 365 to get cost per trip, and by section length to get cost per km. In this example:

  • Road 1: $730,000/10000 = $73/y = $0.20/trip = $0.04/km
  • Road 2: $7,300,000/20000 = $365/y = $1/trip = $0.10/km
  • Road 3: $1,460,000/16000 = $91.25/y = $0.25/trip=$0.25/km

The total is thus $529.25/year or  $1.45/trip to cover land rent. `Your mileage may vary,’ as the saying goes.

Implications

The implications of this are several.

  • At an additional $1.45/trip, travel by car (and congestion) will diminish.
  • Road rent is essentially additive with annualized infrastructure costs, which generally does not consider the cost of land (rather, land is often implicitly considered `free’ or a sunk cost).
  • If travel by car diminishes sufficiently, road space can be clawed back and redeployed for other public purposes.
  • Narrower lanes impose less road rent. But not necessarily proportionately so, as the throughput on narrower lanes (with human drivers) may be lower as drivers are less keen to be immediately adjacent to nearby high-speed vehicles.
  • Slower moving vehicles take up less space, but take that space for longer.
  • While pedestrians and bicyclists use space as well, they use much less space. (See discussion of flux.) Sidewalks (footpaths) are often considered part of the adjacent private property, and are thus already paid for with property tax.
  • Land used for roads instead of development is not on the books for property taxes.
  • The revenue raised can be used for many transport purposes or redistributed back to taxpayers through some other means.
  • We expect the additional road rent reduces the effective land rent that landowners can charge. If people have to pay more for travel, they will pay less for real estate.
  • Rural areas have much lower, perhaps negligible, road rent. Though the number of users drops significantly (so there are fewer travelers who must pay the burden of road rent), the cost of land drops even more significantly.
  • Were there no (fewer) roads, land would also have very little (less) value, since it would be difficult to access and egress.
  • If roads were fully built on, views would be terrible and the existing buildings would diminish in value. But none of that is to say we have the correct amount of roads now. Clearly urban roads are undercharged in a real estate sense.

Cage the Automobile

Is the purpose of bollards to keep people in or keep cars out? A reader writes:

 

Bollards done wrong, Egypt.
Bollards done wrong. It’s a long pedestrian street, would you bollard the entire street,  because they are proposing low risers. You will end caging the people like in Egypt.

After the attack in Toronto last week with a guy driving a van and killing 10 people and injuring 15, Montreal announced a new plan for Saint Catherine street making it pedestrian friendly, with a nice wide sidewalk showing young people walking, yet  when the mayor was asked if they planned for pedestrian safety from such attack she said ‘no, we did not.’

So the moral question: should we change our planning for pedestrians to ensure safety from a crazy person in a van, terrorists, drunk drivers,  just incapacitated drivers. This is not the first, and will not be the last, time a driver plows down pedestrians. By doing so we show weakness to terrorists? Are we converting the outdoors to a Zoo placing pedestrians in cages. Should the woonerf, for example, be like an open zoo.

It’s a moral and ethical question how much separation should we have in an era when crazy people uses cars as weapons to kill random humans. How many incidents and deaths will it take to change the approach for pedestrian environments to make it as safe as air travel.  If we  add more small obstacles, how much will they spoil the pedestrian environment and sense of freedom.

 

The crazy person in a van problem is only going to get worse with automation and especially connectivity, a remote control car bomb is even easier than a suicide.

This Delft Bollard is a casualty of the Car Wars.

In my view, cars should be in the cages, the people should be free. And then the cages need to be made smaller and smaller.

All urban streets in heavily pedestrian trafficked areas should have bollards or equivalent to keep the cars away from the people. Woonerfs are fine for residential streets, and if people want to encroach on shared space that is also fine, but cars should not encroach on people space. Just as we don’t let cars in most buildings, there should be outdoor public spaces where they are also prohibited.

We don’t need fences or chains like in the photo of Egypt, just lots of posts (trees, bike racks, benches, bus stops, street furniture, planters etc.) that make it impossible for a car to run down the sidewalk or into buildings. This furniture of course should not interfere with the free flowing movement of people, and might require taking lanes from the storage, or even movement, of cars. As with all good urban design, examples of this are in Delft, with some lowerable Bollards to allow service, emergency, and freight vehicles in when needed.

 

Delft defining Pedestrian domain.
Delft, lowerable Bollards on a bridge

 

 

 

 

 

Speed vs. Safety

March 21 [Updated with more accurate estimate/figure after fixing an excel bug] How fast should we drive? From a social cost perspective, faster speeds save time, which has a value, but faster speeds cost lives, which also have a value. To illustrate the trade-off I did some back of the envelope calculations, imagining, like a macro-economist, a single road represents the whole t

Speed vs. Safety (updated)
Speed vs. Safety (updated)

ransport system. Annually there are about 30-40,000 people killed in the US, there are an annual Vehicle Miles Traveled of 3,208,517,000,000. The average speed of travel isn’t known directly, but if we assume the average person travels in a car 60 minutes per day (the 1 hour travel time budget) this implies, at approximately 30 miles of travel per day per traveler, about 30 MPH, which seems about right (including 1/4 of travel on freeways at higher speeds and 3/4 on surface streets and roads at lower speeds, and including traffic signals). As the saying goes, Your Mileage May Vary, and this is intended to be indicative — not a universal answer. Some additional assumptions:

  • We take the Value of Life to be $10,000,000, and assume fatalities are the only cost associated with crashes (they are about 78 % of total crash costs according to our analyses, so we should inflate this number to get total crash costs) [US DOT says $9.6 M]
  • We take the Value of Time to be $15/hour [US DOT gives a lot of ranges, but this number is high for all surface travel excluding freight]
  • We assume the number of deaths drops linearly with speed, to zero at zero MPH. The improvement is likely non-linear, as reductions in speeds from high speeds are more valuable than from low speeds.
  • We assume the value of travel time savings is constant, independent of the amount of time saved.

To be clear, these are huge assumptions. Examining the figure we see the lines cross at about 75 MPH, which is the minimum total cost. So why don’t we set the speed limit to  75MPH? Note that:

A Political Economy of Access: Infrastructure, Networks, Cities, and Institutions by David M. Levinson and David A. King
A Political Economy of Access: Infrastructure, Networks, Cities, and Institutions by David M. Levinson and David A. King
  • Travel time savings are, while still speculative in terms of their valuation, both private and real,
  • The statistical value of life is far more abstract. The value of my life to me is infinite. The value of your life to me is, sadly, not. Yet, I am willing to take risks that increase the probability of my dying in order to save time or earn more money. These are the kinds of factors that allow an estimate of value of a statistical life.
  • Death and crashes are probabilistic affairs, while the time lost is deterministic. People are gamblers.
  • There are some other benefits to faster travel not accounted for, such as more or longer trips (to better destinations, or the ability to get better real estate at the same price), which increase consumer surplus. The analysis here does not consider user response to lower speeds, which would be to travel less (or higher speeds and travel more).  There are also issues like travel time reliability.
  • Since 1988 The Statistical Value of Life has risen 6-fold in US DOT estimates, the value of time has little more than doubled. (If we cut the value of life to $3M, (effectively holding the tradeoff more similar to 1988 levels), the tradeoff is much higher .)
  • Speed limits reflect what travelers will travel at, not what we wish they would travel at.

If you dislike these number, you can roll your own analysis on individual roads. The difficulty is not measuring the speed of those roads, but measuring their safety. There is a Highway Safety Manual for such purposes, but crashes are highly random events.

UPDATE 2: Axel Waleczek made an interactive Tableau, so you can test your own scenarios.

Additional Readings

Up or Out: Travel Demand and Thirty Minute Cities

Adapted from Levinson, D. and Krizek, K. (2017) The End of Traffic and the Future of Access. Network Design Lab. Cross-posted on the ITLS Thinking Outside the Box  blog.

Each technological advance in mobility over the past 200 years increased the size of metropolitan areas. The ability to go faster, either owing to new technologies or more completely deployed and deeply connected networks, allowed people to reach more things in less time. The Underground drove the expansion of London, streetcars did the same for many American cities,[a] while trams and trains made Sydney, Melbourne, and Brisbane among others, and highways have exploded the size of cities everywhere. Historically, the time saved from mobility gains was reflected mostly in additional distance between home and the workplace, maintaining a stable commuting (home to work) time.

Will autonomous vehicles follow the path well worn by earlier technologies?

Fast, driverless cars that allow their passenger to do things other than steer and brake and find parking impose fewer requirements on the traveler than actively driving the same distance. Decreases in the cost of traveling (i.e., the availability of  safe in-vehicle multitasking) makes travel easier. Faster roads arise because of capacity gains from vehicle automation (due both to closer following distances and narrower lanes, even more practical with narrower vehicles fit to serve the single passenger they usually carry). Easier travel means increases in accessibility and subsequently increases in the spread of development and a greater separation between home and work, (pejoratively, `sprawl’), just as commuter trains today enable exurban living or living in a different city.[b] Autonomous automobility reinforces the disconnected, dendritic suburban street grid and makes transit service that much more difficult (as if low density suburbs weren’t hard enough). People will live farther ‘Out.’

However, concomitant with automation is the emergence of the sharing economy, with at least some people transitioning from today, where the typical Australian owns their own car, to mobility-as-a-service (MaaS) — automated taxis. This is more likely in larger, central cities where taxis are common, auto ownership is already difficult, and parking scarce and expensive. In this world, while the total cost of travel drops as vehicle ownership costs disappear, the cost per trip might rise, as the cost of ownership is allocated to each trip. This reduces travel demand.

Driverless cars which can be summoned on-demand allow people to avoid vehicle ownership altogether. This reduces vehicle travel, as people will pay more to rent by the minute than exploit the sunk costs of vehicular ownership. By saving total expenditures on transport, more funds are available to pay for rent in cities, and more trips are by walk, bike, and transit. People who seek the set of urban amenities (entertainment, restaurants, a larger dating pool) will find these amenities increasing in response to the population. The greater value in cities with the new more convenient technology leads to more and taller development. (Hence the use of the word ‘Up.’)

At first blush, ‘Up’ and ‘Out’ appear to be contrasting scenarios; they are not exclusive, however. More people living in the outer suburbs or exurbs does not mean fewer people live in cities, because the overall size increases (with more people overall). Sydney for instance, is expected to grow from just over 5 million to about 8 million people over the next four decades.

Similarly, as the cost of travel decreases, people will be more willing to live in locations far from where they work. At safe speeds of 160 km/h on freeway lanes exclusively dedicated to automated vehicles, the commuting range expands widely. From Sydney in this new world, Newcastle can be reached an hour on road, and Kiama and Katoomba are even nearer.

Sydney planners have recently proposed the benchmark of the “30-minute city“, the idea that most people can find work, school, or daily shopping within 30 minutes of their homes by walk, bike, or transit. The threshold of 30-minutes is roughly equal to today’s one-way commute in Sydney (actually 35 minutes), shorter by car (26 minutes), longer by train (62 minutes) according to BITRE. The long times by train are because trains are designed to serve longer distance trips, and focus on the Central Business District.

The End of Traffic and the Future of Access: A Roadmap to the New Transport Landscape. By David M. Levinson and Kevin J. Krizek.
The End of Traffic and the Future of Access: A Roadmap to the New Transport Landscape. By David M. Levinson and Kevin J. Krizek.

The 30-minute city can be achieved through a combination of transport and land use strategies. On the transport side is the question of how fast and how direct the transport network is. On the land use side is the question of where desired activities are located relative to each other.

If the 30-minute city is defined for walk, bike, and transit as the relevant modes, with mobility-as-a-service easily available on-demand, the Up Scenario works best, though getting one-way commuting times for train users down from 60 to 30 minutes is a large ask. In contrast, the Out Scenario can continue to enable a 30-minute city for privately owned autonomous vehicles so long as jobs don’t centralize further in downtowns.

The interplay of AVs and road pricing is especially important. While autonomous vehicles may eventually double or quadruple road capacity, total demand will rise as well due to population growth, so long as people continue to work, shop, and play outside-the-home at today’s rates, even more if traditional patterns of induced demand hold.

It is quite possible that sharing remains a niche while most people choose to own their own cars — the ‘Out’ scenario dominates. Thus, exurbanization and AVs better leverage newly available capacity. But, in the absence of pricing, and with cheap energy, there is little to discourage tomorrow’s privately owned AVs from circulating empty on the road network rather than pay for high prices of parking, and thereby slow travel for everyone else. This possible outcome is so obviously bad, it suggests road pricing or similarly effective regulation in some form is likely.


 

[a] See Levinson, D. (2008). Density and dispersion: the co-development of land use and rail in London. Journal of Economic Geography, 8(1), 55-77 and Xie, F., & Levinson, D. (2009). How streetcars shaped suburbanization: a Granger causality analysis of land use and transit in the Twin Cities. Journal of Economic Geography, lbp031.

[b] For more on this reasoning, see Chapter 11 in Levinson, D. and Krizek, K (2008)  Planning for Place and Plexus: Metropolitan Land Use and Transport. Routledge.

The Ambiguous Hump

How about an ambiguous hump to start your Valentine’s Day ?  Pedestrian / street interfaces in Sydney are needlessly inconsistent. When is a Speed Hump (Speed Table) also a Pedestrian Crossing? When is a Pedestrian Crossing also a Speed Hump? When the traffic engineer felt like it.

Walking about Sydney, we see all sorts of cases. I propose a simpler rule: All high demand pedestrian crossings should be speed humps on the road (the should rise to the sidewalk level). All low demand roadway/sidewalk crossings should be speed humps so that these road and especially  laneway (alley) crossings extend the sidewalk across the road (so the pedestrian is not lowering themself crossing the street, but rather the car is slowing and rising while crossing the sidewalk). I have photos illustrating good, bad, and ambiguous examples from Sydney.

A midblock raised crosswalk/speed hump at the busy entrance to the Broadway Shopping Center. This is excellent, and cars reluctantly yield to the dominant pedestrian. The walk leads to escalators. (Mid-right)
A midblock raised crosswalk/speed hump at the busy entrance to the Broadway Shopping Center. This is excellent, and cars reluctantly yield to the dominant pedestrian. The walk leads to escalators. (Mid-right)
A raised sidewalk across a laneway (alley) at Broadway Shopping Center. This is also excellent, and should be ubiquitous at every laneway in Sydney. The pedestrian is giving me the side eye for taking his picture, but he is important to illustrate traffic safety.
A raised sidewalk across a laneway (alley) at Broadway Shopping Center. This is also excellent, and should be ubiquitous at every laneway in Sydney. The pedestrian is giving me the side eye for taking his picture, but he is important to illustrate traffic safety.
Raised pedestrian crosswalk in Cronulla
Raised pedestrian crosswalk in Cronulla. Similar to the first example at Broadway, but a much less trafficked intersection, with a too narrow bikelane on the side. The sidewalk comes down to the street before the pedestrian rises above the street, and then returns to grade before the next accessibility ramp. Not quite an elegant solution.
Redfern Station Entrance. There is no marked crosswalk, much less a speed hump or raised sidewalk here, despite the huge demand. There is however a speedhump just to the east (left) of the picture for some reason. A missed opportunity. No marked crosswalk means pedestrians must yield to cars.
Redfern Station Entrance. There is no marked crosswalk, much less a speed hump or raised sidewalk here, despite the huge demand. There is however a speedhump just to the east (left) of the picture for some reason. A missed opportunity. No marked crosswalk means pedestrians must yield to cars.
The intersection of Abercrombie Street and Cleveland Street in Darlington (Chippendale is across Cleveland) sees a speed hump on Abercrombie between Hudson Street (the lower right) and Cleveland (upper right). Pedestrians are continuously crossing in this stretch, but the speed hump aligns with neither unmarked crosswalk. Still, it's begging for pedestrians to use it, and they do.
The intersection of Abercrombie Street and Cleveland Street in Darlington (Chippendale is across Cleveland) sees a speed hump on Abercrombie between Hudson Street (the lower right) and Cleveland (upper right). Pedestrians are continuously crossing in this stretch, but the speed hump aligns with neither unmarked crosswalk (at Hudson/Abercrombie nor Cleveland/Abercrombie). Still, it’s begging for pedestrians to use it, and they do.
A signalized but porkchop-islanded crosswalk at a Free Left (Free Right for those in the right-side drive countries). Notice the pedestrian light is red (don't walk) but the pedestrians cross anyway. If the free left is not eliminated in a more comprehensive redesign, it could easily be de-signaled and the crosswalk raised, so pedestrians dominate, and cars travel when they can.
A signalized but porkchop-islanded crosswalk at a Free Left (Free Right for those in the right-side drive countries) (Broadway and City Road). Notice the pedestrian light is red (don’t walk) but the pedestrians cross anyway. If the free left is not eliminated in a more comprehensive redesign, it could easily be de-signaled and the crosswalk raised, so pedestrians dominate, and cars travel when they can.
This speed bump does not want to be mistaken for a pedestrian crossing, so it is landscaped whereever a pedestrian might think of crossing. This is just before the actual intersection, on an extensively calmed street.
This speed bump in Alexandria Park does not want to be mistaken for a pedestrian crossing, so it is landscaped wherever a pedestrian might think of crossing. This is just before the actual intersection, on an extensively calmed street. Cars race from calming device to calming device, treating the chicanes the way a skier might.