Elements of Access: What are we talking about, when we talk about trips?

by Kay AxhausenTrips2 Trips1




The image shows a daily schedule with 2 tours including 1 subtour, 8 trips and 18 stages.

No surprise, but professional and everyday language overlap in their vocabulary, while not identical in their meanings. In many fields this is not a big problem, as the technical and professional discourse do not overlap, as laymen rarely read or hear the technical discourse, but for the students at the beginning of their training. In transportation it is a problem, as the professionals have to address the public as voters, decision makers or respondents in surveys. They talk with each other continuously.

As expected, transport planners and engineers have developed a detailed vocabulary to talk about movement, unfortunately even differing ones for the different modes of transportation. Roget’s Thesaurus give as synonyms trip, journey, excursion, cruise, expedition, foray, jaunt, outing, run, swing, tour, travel, trek, errand, hop, junket, peregrination, ramble. They clearly have connotations, which make one more suitable for certain occasions, but they can be used interchangeably for a movement from A to B and back.

Elements of Access: Transport Planning for Engineers, Transport Engineering for Planners. By David M. Levinson, Wes Marshall, Kay Axhausen.
Elements of Access: Transport Planning for Engineers, Transport Engineering for Planners. By David M. Levinson, Wes Marshall, Kay Axhausen.

Observing and thinking about movements for a moment it becomes clear, that a ‘trip’ will have smaller building blocks and might belong to something bigger, say a vacation. The professionals have given names and a structure to these, so that they can measure and talk about them clearly. The layman might want to appreciate the differences when he or she listens to a policy proposal arguing with them.

The key terms are stage, trip, tour, daily schedule with their variants in different countries and industries. A stage is the smallest unit, the movement from A to B with one mode ore one vehicle of that mode: walking from home to the bus stop or flying from the first airport to the hub airport are stages. The airline industry talks about legs and means the same thing, as do American planners when they talk about ‘unlinked trips’. In logistics the stage with the longest distance is generally called the ‘main haul’.

A sequence of stages from one activity to the next is a trip, which now requires a definition of activity. Following the example of time use studies and sociology, the activity is defined as a meaning interaction with another person or task. In transportation a trip is always one way.

A sequence of trips from A via various other locations back to A form a tour. Journey is used to specify tours starting and ending at home. One runs into problems, if one wants to talk about tours within tours, for example going to lunch and coming back to the workplace. Some parts of the literature talk about sub-tours then. Equally, other parts of the discussion need a word to talk about the movement from home to the main stop of the tour. You will find the word ‘commute’ to describe just this, even if it includes activities, such as dropping out the children at school, a quick coffee at Starbucks and time at the gym before arriving at work.

The daily schedule are all the tours undertaken between getting up and going to bed again.

It should be clear now, that discussion about mode choice should always refer to the element talked about. Walking (stages) will always be part a trip to reach the vehicle(s). Walking will therefore always have the highest mode share among the stages, but not of the miles travelled. At the higher levels the planners have to decide which mode they allocate to the trip or tour. Normally they choose the mode of the stage with the longest distance. In this process the other stages are forgotten and often their mileage allocated to the maid mode. The chances for confusion are endless, unless this is made clear.

Remember: Tours are sequences of trips, which are sequences of stages.



Shaping a new funding model for public transit in Quebec

Jason Magder writes in the Montreal Gazette: Shaping a new funding model for public transit in Quebec

David Levinson, who teaches in the department of civil, environmental, and geo-engineering at the University of Minnesota, said there are several ways to capture the value of transit developments without taxing citizens heavily.

One idea is to reverse the way property is taxed so that the land portion is taxed more heavily than the development portion.

“You should tax the land more. That way, you encourage development as a way to pay for transit, instead of having all these lots of land lying fallow,” he said.

Another method of capturing the value of real estate is for the transit agencies themselves to purchase land around future stations and then develop them, or sell them off.

Any future agreement with the Caisse to build the two train projects will probably end up with the Caisse owning the train stations so that the pension fund can develop commercial or residential properties.

Levinson noted that the city of Vancouver is particularly good at this type of land capture. Land development has helped pay for a portion of the new Canada Line — part of the SkyTrain network that links the suburb of Richmond to the airport and the city’s downtown centre. The transit agency in Vancouver, Translink, is in the process of buying up land around a proposed subway, at least 10 years before the project’s construction is slated to start.

Vancouver is looking to find new sources of revenue to fund a $7.5-billion 10-year wish list, which includes a four-stop subway, and extensions of the SkyTrain network. The city has proposed to increase the provincial sales tax in the metro Vancouver region from 7 to 7.5 per cent to pay for the project, and a write-in plebiscite on the proposal will take place in the spring.

In part 2 Questions surround who should make decisions about future transit projects, he writes:

David Levinson, who teaches in the department of civil, environmental, and geo-engineering at the University of Minnesota, said the London model is worth exploring.

He said it forces transit agencies to think more like companies, and make decisions on projects based on where the service is most needed, in a way that will provide the best value for investment.

“The only way that public transit is sustainable is if it’s serving customers,” he said.

He said the London model still relies on the government to subsidize less busy routes. Private bus companies also compete to run routes that are not profitable.

Levinson said rather than pouring more money into transit, government policies should make it more expensive to use a car to travel, by charging what’s called a congestion tax to drive into the city.

He said governments must make it more expensive to drive, and that will automatically give a major boost to public transit.


TCRG: Observing Accessibility

I will be presenting at the Twin Cities Research Group at 12 Noon at the Wilder Foundation building at University and Lexington on Wednesday March 11
Title: Observing Accessibility
Abstract: Using data from the Access to Destinations Studies and the Access Across America Studies, this talk discusses both the measurement of accessibility, why it matters, and how it might affect traveler behavior, institutional behavior, and public policy. Looking at data from rail development in London in the 1800s, the Twin Cities from 1995 to the present, and 51 metropolitan areas across the US, implications about the effects of accessibility are described, and the rationale for a National Accessibility Evaluation is presented.
(This is a sequel to my August 2009 talk: Destinations Count)

What if car driving is like playing chess


JS Writes in with an intriguing idea:

“What if car driving is like playing chess?  Self-driving cars may be possible and even valuable but the safest most efficient driving may be the combination of the computer and the person/people.  What if one Uber “driver” could drive 10 cars at once, or a team of 3 Uber drivers could drive 100 cars?”

And then sends in the following from the EconTalk podcast …
From Econtalk: Tyler Cowen on Inequality, the Future, and Average is Over 11:01


Russ: So let’s talk about what you’ve learned as a chess fan. And you write at some length. At first I was rather taken aback by this, but I grew to find it quite fascinating. You write at some length about the role of machines in chess tournaments, and particularly in freestyle. Talk about that and why it’s a nice potential template for future human interaction.

Guest: Freestyle is a form of chess where a human teams up with a computer. So, if you play human-and-computer against computer, for the most part human-and-computer, if it’s a practiced human, will beat the computer. Even though computers per se are much stronger than humans at chess, it’s the team that’s stronger than either one. And I think this is a good metaphor for a lot of what our job market future will look like. So there’s a big chunk of the book that looks rather closely at freestyle chess and tries to see what we can learn from it.

Russ: The thing I found most provocative about that is that the best freestyle teams do not necessarily have the best human players. In fact that could be something of a handicap.

Guest: That’s right. The really good human players are too tempted to override the computer and substitute in their own judgment. The best freestyle teams, they are quite epistemically modest, the human or humans involved. And what they are really good at is asking questions. So they’ll run two or three different computer programs and then just check on where do those programs disagree. And then they’ll probe more on those points. And that’s what the humans do well that the computers, at least not yet, aren’t able to copy. So it’s knowing what questions to ask that has become the important human skill in this freestyle endeavor.

I still think we will need to turn it all over to the computers, and the sooner the better. Human intervention will need to be so real-time that it is likely to be worse than the algorithm, and the lags in communication are sufficient to be debilitating. But the history of self-driving cars has yet to be written.

Governing transit: the regulated public utility | CityBlock

Alex Block over at the City Block blog writes about Governing transit: the regulated public utility.

The MBTA is struggling, but they’re not the only transit authority facing both near and long-term challenges. The MTA in New York is trying to find the funds for its capital plan; WMATA is facing systemic budget deficits while trying to restorerider confidence in the system.

For-profit corporations such as airlines aren’t the right answer to govern transit in an American context. So, what kind of structure could work?

Writing at Citylab, David Levinson made the case for structuring American transit operations as regulated public utilities, able to pull the best elements of private sector management and pair them with the fundamentally public purpose required for urban mass transit.

David cites seven key elements of this model:

  1. Competitive tendering for services
  2. The ability to raise fares (with regulatory approval)
  3. Using a smartcard as a common platform for fare payment
  4. Specific contracts with local governments to operate subsidized service
  5. Ability to recapture land value through land ownership and real estate development
  6. Access to private capital markets
  7. Local governance, funding, and decision-making

These elements aren’t substantively different from the elements of German public transport governance reforms outlined by Ralph Buehler and John Pucher: competitive tendering for many services, increased fares, investments in technology to improve capacity, efficiency, and revenue. Public regulation oversees these efforts to operate the core business more efficiently.


Elements of Access: Induced Demand

Induced Demand
Induced Demand


by Wes Marshall

You already have a congested roadway, and the transportation planners predict even more traffic on that road in the near future. What do you do? For most of the last century, the answer was to increase capacity. In the short-term, this seemed to work. Time and time again, over the long-term, the actual amount of traffic after the capacity increase grew far more than expected. What seemed like an obvious solution to a congestion problem continued to disappoint. But why?

The reason for these failures lies with the principle of induced demand. Once capacity increases, not only do you get the originally predicted traffic growth, but you also facilitate some often unanticipated changes in travel behavior. First, existing road users might change the time of day when they travel; instead of leaving at 5 AM to beat traffic, the newly widened road entices them to leave for work with everyone else. Second, those traveling a different route might switch and drive along the newly widened option. Third, those previously using other modes such as transit, walking, bicycling, or even carpooling may now decide to drive or drive alone instead. Together, these unwanted behavior changes fall under what is termed the theory of triple convergence (also known as the ‘Iron Law of Congestion’). This latent demand induces more traffic than originally expected and saps the supposed improvement of the expected benefits.

The joke is that adding lanes to cure congestion is like loosening your belt to cure obesity. Empirical results over the last century – due to the principle of induced demand – have borne out that this issue is real and should always be accounted for when considering adding capacity as a solution to congestion.

Elements of Access: Transport Planning for Engineers, Transport Engineering for Planners. By David M. Levinson, Wes Marshall, Kay Axhausen.
Elements of Access: Transport Planning for Engineers, Transport Engineering for Planners. By David M. Levinson, Wes Marshall, Kay Axhausen.







Downs, A. (2004). Still Stuck in Traffic. Washington DC, Brookings Institute.