Month: August 2013

Another HOT Post

| David Levinson

Peter Samuels at TollRoadNews writes this about Randall Pozdena (ECONorthwest) take on our HOT Study (previously discussed at TollRoadNews). Average value of time saved irrelevant to toll express lanes – Randall Pozdena ECONorthwest :

“2013-08-30: It’s not the average value of time saved (VoTS) that’s relevant to users of toll express lanes running alongside free lanes. It’s the higher time saved values of a small proportion of trips that choose the express lanes that determines how much the minority using express lanes will pay – the VOTS of the top decile or two of the distribution of total trips in the corridor.

Randall Pozdena, managing director and senior economist at ECONorthwest in Portland OR makes this point in comment on our reporting of a University of Minnesota study of motorist behavior on the 394 and 35W toll express lanes in the Minneapolis area by Michael Janson and David Levinson. We’d reported the researchers’ surprise at the very high values of time saved they’d observed in the Minneapolis toll lanes  – that drivers in express lanes regularly pay $1 to $2 per minute saved, or $60 to $120/hour.

That compares to full tollroad average driver payments of $15 to $30/hour.

The main thrust of our report was on the Janson-levinson discovery that toll rates can have a definite proxy effect – high rates being seen as a proxy indication of high congestion shifting the demand curve to the right.

But the other newsworthy findings of the study seemed to be the very high VOTS measured and the Janson-Levinson explanation that motorists may have an exaggerated sense of the time they save. They are behaving with imperfect knowledge, and systematically biased perception of what time saving they’re buying.

Pozdena sees it quite differently.

He says people using toll express lanes are acting rationally and while their knowledge is imperfect he sees no systematic misperception.

‘In a toll express lane setting, implicit values of time are very likely to be that high ($1 to $2/minute saved.)  The reason is that the ‘conventional’ value of time is actually an average, but in the real world, there is a log-normal distribution around that average that reflects not only the distribution of income, but also the urgency of the trip at the instant.  Thus, the users who self-select to pay to join the toll express lane are drawn selectively from the UPPER TAIL of the VoT distribution, and would not be expected to display average values of time.’

He says ECONorthwest has developed a model for toll optimization model that is based on calculating the shape of the distribution of values of time.

‘We take the regional model average VoT and form a distribution around that mean in a key step in the data flow called ‘VoT Transform.’  

He adds that at ECONorthwest they ‘routinely find our model predicting that the MARGINAL value of time of those who are skimmed off to the HOT lane is several multiples of the AVERAGE value of time, and the average of those above this cutoff would be even higher.  Thus, I don’t think that one can conclude that HOT lane users think they are getting ‘greater time savings’ than they really are.  They are just the folks with long-tail values of time.’

Pozdena says the proxy effect is not a problem if the pricing system is working as it should and prices according to density of vehicles. It is conveying good information to motorists about conditions they can expect.”

Obviously there is a long-tail (one cannot have a value of time below zero, but one can have a value of time of $200/h). Further, people using the toll lanes must have a higher value of time than those who do not use the lanes, at that time. The question is the composition of rational and fully-informed travelers vs. misperception (for which, contra Pozdena, we do have evidence) vs. emotionality vs. concern about reliability vs. principal agent problems (someone else’s money) vs. any of the other factors that influence route choice and lane choice. These are all components in the choice of different individuals, and we don’t know enough to accurately ascribe the choice to each component.

I shriek the wail of every scientists: more research is needed.

Who’s Out There On The Roads? The 4 Types Of Cyclists – Forbes

| David Levinson

Forbes cites Nexus alumnus and McGill Professor Ahmed El-Geneidy on the 4 Types of Cyclists … Who’s Out There On The Roads? The 4 Types Of Cyclists:

“Path-using cyclists (36 percent) are motivated by the fun of riding, its convenience, and the identity that cycling gives them. They’d rather use a continuous route, rather than dodge cars. They were actively encouraged by their parents to ride for fitness and to get places.

Dedicated cyclists (24 percent) are motivated by speed, predictability and flexibility that bike trips offer. These cyclists are the least likely to be deterred by the weather. They aren’t as interested in bike paths, and actually enjoy riding in traffic. The researchers say these cyclists consider riding to be an important part of their identity.

Fairweather utilitarians (23 percent) are just that. They like to ride in good weather, and they’ll take another form of transportation in rain or snow. These are also bike path users, and they don’t necessarily see themselves as cyclists.

Leisure cyclists (17 percent) ride because it is fun, and not as much for commuting. They prefer bike paths, don’t like to deal with traffic, and want to feel safe, especially when riding with family members.”

You have got to love renderings

| David Levinson

Henn222

I found this rendering of 222 Hennepin earlier today, after reading Bill’s post on architecture. The part that I liked best is the traffic light. First it is sideways, a design that is used in some places in the world, but not Minneapolis, for a lot of good reasons.

I grew up in Columbia, Maryland, which for many years had sideways traffic lights, mainly as an architectural distinction, but which were abandoned because of the confusion created.

A major problem of such uncommon lights is that color-blind person might not know if the green is on the left or on the right. In Wisconsin (as everywhere else in the US where it is done, and standardized in the MUTCD, it is red on the left, green on the right.

In the rendering, it is the opposite.

It makes you wonder what other tricks and graphical shortcuts are going on to make the rendering desirable to approve and move into, but won’t really turn out as implied.

SignalX

SidewaysLights

Do Streetcars Promote Economic Development? | streets.mn

| David Levinson

Now at Streets.MN: Do Streetcars Promote Economic Development? :

 “It is often said that “Absence of Evidence is not Evidence of Absence”, but this is wrong. This is especially wrong in a context were we have motivated people searching for evidence. Consider the example of Bigfoot. Bigfoot is a supposedly big humanoid / primate living in very small numbers (and presumably hiding from humans). There was a fad in my youth for blurry pictures of Bigfoot to appear in weekly tabloids sold at supermarket checkout stands. However, as XKCD points out, cameras are everywhere now, on billions of phones, and yet we have no more evidence of Bigfoot than before.”

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

Do Streetcars Promote Economic Development?

by  on August 26, 2013 in Streetcars
As Bill notes, the Metropolitan Council argues that Streetcars are more for Economic Development than for Transportation, and so should be seeking a different pot of money.

We have evidence in many historical cases of the co-evolution of transport and land use (e.g. London, New York, Twin Cities). In those cases the transport mode developed was faster than alternatives, and therefore increased accessibility, making land more valuable.

ComoHarriet

We have no evidence that streetcars, of themselves, promote economic development in the context of present-day US cities. That is, there is no case where modern streetcars were built, nothing else was done by the public sector (no road reconstruction, no public subsidies for development, no change in development regulations), and the level of private sector economic development changed measurably, and more than in an otherwise comparable control case.

We have hypotheses as to why there should be no effect, and that is the maturity of the system (streetcars are not connecting places that are presently unconnected) and the lack of positive changes to accessibility (or even negative changes to accessibility) that comes with adding a slow mode to a network which is already faster.

It is often said that “Absence of Evidence is not Evidence of Absence”, but this is wrong. This is especially wrong in a context were we have motivated people searching for evidence. Consider the example of Bigfoot. Bigfoot is a supposedly big humanoid / primate living in very small numbers (and presumably hiding from humans). There was a fad in my youth for blurry pictures of Bigfoot to appear in weekly tabloids sold at supermarket checkout stands. However, as XKCD points out, cameras are everywhere now, on billions of phones, and yet we have no more evidence of Bigfoot than before.

Does this constitute “proof” of the non-existence of Bigfoot? No, because one can never prove a negative (See Popper on Falsifiability). It does however cause the rational among us to become increasing skeptical about our hirsute friend’s likelihood of being real.

The very logical Less Wrong blog discusses this issue: Absence of Evidence Is Evidence of Absence :

“But in probability theory, absence of evidence is always evidence of absence. If E is a binary event and P(H|E) > P(H), “seeing E increases the probability of H”; then P(H|~E) [Probability of H given Not E] is less than P(H), “failure to observe E decreases the probability of H”. P(H) is a weighted mix of P(H|E) and P(H|~E), and necessarily lies between the two.”

Bigfoot

We need to think in “but for” way when evaluating economic development claims.

Would the development not occur “but for” this particular investment? Would it occur with streetcars and BRT, with only streetcars, with only BRT, with neither?

We can’t fully know this without running 4 experiments in 4 parallel universes. We can estimate this statistically by looking carefully at multiple cases that have already opened, under multiple conditions, and get likelihoods that effects are as estimated by the model. There are some examples of modern transit lines increasing property values, there are some examples of no effect, and there are even some examples of transit lines destroying wealth (sometimes all found in the same study, e.g. Rail Transit Investments, Real Estate Values, and Land Use Change: A Comparative Analysis of Five California Rail Transit Systems by Landis et al.). Once lots of these studies are done, we can do a meta-analysis, and try to put the complexity of findings into some order. The meta-analysis is much more robust, in that it essentially has the combined sample size of all of the studies it takes in. For instance, see The Impact of Railway Stations on Residential and Commercial Property Value: A Meta-analysis . These studies unfortunately do not generally apply to modern streetcars, which have very different characteristics than high capacity services.

There have been a few attempts to summarize the results of the Streetcar and economic development debate:

None of the reports about economic development effects have survived a rigorous peer review process. So in the end, we equivocate. If the new transportation infrastructure notably increases the relative accessibility of a place (compared to other places), it might attract some development that would otherwise go elsewhere. If it signals to developers to coordinate actions, and develop here, rather than there, it might also concentrate development. If we concentrate development, and create more accessibility, we might have some economies of agglomeration further driving growth. If, If, If.

The evidence we do have is that employment in the core cities of Minneapolis and St. Paul is very stable, independent of most of the vagaries of the economy, shifts from low rise to skyscrapers, construction of freeways and skyways, the expansion of the University, the rise of the dual worker household, and so on.

The table below shows employment in Minneapolis and St. Paul from 1970 – 2010.

 

St. Paul Minneapolis
1970 170490 265090
1980 176900 268600
1990 172578 278438
2000 188124 308127
2010 175933 281732

Do we really believe a small investment in infrastructure serving a thousand additional people per day will move this? That would be the equivalent of urban homeopathy.

 

An anonymous source nicely summarized some publicly available information (Nicollet Alternatives Analysis and Met Transit’s Arterial BRT study) of the costs and ridership of all alternatives.

Line Length(miles) 2030 Avg Weekday Project Boardings 2030 Avg Weekday New Riders Capital Cost (million $) Operating Cost (million $) Capital Cost / Weekday Rider
Enhanced bus 9.2 13,400 -1,700 94 13.6 $7,015
Streetcar 9.2 19,900 900 393 20.1 $19,749
Streetcar starter line 3.4 7,200 1,200 200 10.6 $27,778
Met Transit aBRT 21.8 34,700 6,700 110.7 9.06 $3,190

And if you prefer your denominator to be riders per mile of construction rather than riders:

Cost / Rider / Mile
$762.49
$2,146.60
$8,169.93
$146.34

Upzoning and development would be factored into all alternatives, especially since a number are already being developed without a streetcar or other improvement. These ridership projections also include the AA’s assumption that streetcar riders perceive a 25-minute travel time savings (implicitly making their travel time negative in some cases), and thus more choose streetcar.

We need to consider that the Met Council would likely ask Minneapolis to cover most if not all operating costs. That means Minneapolis alone is responsible for $10 – 20 million per year, without a legislature or whole large transit apparatus to back the City up. And that’s only one line.

Advocates will advocate, that is their nature. If no one believes their small estimates of economic impact, the estimates will just grow and grow, just so they can get attention. But don’t confuse their advocacy with scientific knowledge, about which we have very little.

Streetcars are an amenity, like stadiums, festival marketplaces, Entertainment blocks, and new convention centers.

Are they the best amenity? Are they the best transportation service possible? Or do they drain resources that would otherwise be spent on something else, like maintaining and improving existing transit systems or serving many more passengers with Arterial BRT?

 

The Rolling English Road

| David Levinson

Before the Roman came to Rye or out to Severn strode,
The rolling English drunkard made the rolling English road.
A reeling road, a rolling road, that rambles round the shire,
And after him the parson ran, the sexton and the squire;
A merry road, a mazy road, and such as we did tread
The night we went to Birmingham by way of Beachy Head.

I knew no harm of Bonaparte and plenty of the Squire,
And for to fight the Frenchman I did not much desire;
But I did bash their baggonets because they came arrayed
To straighten out the crooked road an English drunkard made,
Where you and I went down the lane with ale-mugs in our hands,
The night we went to Glastonbury by way of Goodwin Sands.

His sins they were forgiven him; or why do flowers run
Behind him; and the hedges all strengthening in the sun?
The wild thing went from left to right and knew not which was which,
But the wild rose was above him when they found him in the ditch.
God pardon us, nor harden us; we did not see so clear
The night we went to Bannockburn by way of Brighton Pier.

My friends, we will not go again or ape an ancient rage,
Or stretch the folly of our youth to be the shame of age,
But walk with clearer eyes and ears this path that wandereth,
And see undrugged in evening light the decent inn of death;
For there is good news yet to hear and fine things to be seen,
Before we go to Paradise by way of Kensal Green.

Source: The Collected Poems of G. K. Chesterton (1927)

Path dependence

| David Levinson

If you don’t know where you’re going, any path will get you there.

Path dependence is the idea that where we are today depends critically on where we were yesterday. Some systems are path independent, those that have a single unique equilibrium. Finding the solutions to some math problems is independent of where you start, as long as you follow a particular algorithm.

However, most systems we deal with on a daily basis have some characteristics of path dependence. Where you live might depend on what job you took, which depends on what your previous job was and where you went to school, and a different decision anywhere along the way would change today’s position.

Nowhere is this more true than transportation. On the one hand, it is obvious that certain locations were destined to be important cities because of significant natural advantages. New York has a deep harbor at the confluence of major navigable river. Chicago is at the pivot point between vast agricultural lands to the Northwest and the shortest land path to the East Coast. It was natural railroads would flow through the point on the map we now call Chicago.

On the other hand, many city sites that were selected for natural advantages in one technological era (The Romans selected London and the Dutch and English chose New York in large part for their capability as ports), remain important even after that technology becomes obsolete. With the logistics revolution and the new dominance of container shipping, London’s shipping has moved northeast to Felixstowe as large container ships cannot easily ply the Thames, while New York’s shipping has migrated to the wide open spaces of New Jersey.

The one-time advantages result in a set of complementary investments and inter-related decisions that take on a life of their own. Because of local trading advantages, commodities markets, banks, insurers, and other related organizations located nearby. A critical mass of those institutions felt no need to migrate just because their initial raison d’être vanished. While a building is under construction, temporary framing will often be used until the more permanent structure is erected. Once the final building can stand on its own, the falsework is dismantled. In a sense, everything is falsework for what comes after.

This kind of mutual complementarity happens repeatedly in transportation. Airplanes are the perfect example of mobile capital. If Amalgamated Airlines no longer wants to serve a particular city pair, the airplane can easily be redeployed elsewhere. Yet 80 years into the commercial aviation industry, airlines today serve mostly the same hubs their predecessors did on the Airmail routes of the 1930s. American Airlines is still in Dallas, United in Chicago, Delta (Northwest) in Minneapolis, and so on.

While very few decisions are completely irreversible, transportation decisions come close. Where we place a right-of-way, or an airport will explain where that facility will be decades, or even centuries from now.

A slight deviation from the efficient path to solve a short term problem today will cost travelers time for years to come. It is important to get the design right for the long term. (Undoubtedly this has social costs, see e.g. I-94 through the Rondo in Saint Paul).

But a slight deviation from the path will also change what the long term is. Build a bridge “here” rather than “there”, and then you will adjust all of the roads feeding into the bridge to meet it “here” (instead of “there”). And then land will be developed along the road to “here” to take advantage of the newly created accessibility, properties will be platted, buildings will be built, travel and trade patterns established, and other critical dependencies will come to assume that the bridge is “here”. At some point, say 50 years in the future, the bridge will need to be replaced. Even if “there” was a better location than “here” initially, after five decades of adaptation, it is quite likely that “here” is better now. The whole may have been better were a different initial decision been made, given conditions at the time. Given current realities, that path must now be foregone.

In transportation we say build it right the first time, because there won’t be a second chance. And that is true. But also remember the world will adapt to whatever we do, and we cannot let the perfect be the enemy of the good.

HOT Lanes Are Even More Popular When They’re Expensive – Eric Jaffe – The Atlantic Cities

| David Levinson

Eric Jaffe at Atlantic Cities summarizes some of our recent research:

HOT Lanes Are Even More Popular When They’re Expensive:

“Everyday, sometimes twice a day, commuters in the increasing number of U.S. metro areas with a HOT lane ask themselves that timeless question: to pay, or not to pay. How they answer depends on the toll price, which charges single-occupancy cars for HOT access based on congestion levels. Logic suggests that as the toll goes up, fewer drivers would fork over the money — for the same reason we sit coach on a plane once we see the price of first-class.

But in Minnesota, at least, HOT lane prices are having the opposite effect. As the cost of HOT lanes on Interstates 394 and 35 went up, more commuters were willing to pay the toll. That’s the rather counter-intuitive finding that emerges from recent research by Michael Janson and David Levinson of the University of Minnesota [PDF]:”

This positive relationship between price and demand is in contrast with the previously held belief that raising the price would discourage demand. …

Evaluating Perturbation Impact on Key Travel Models

| David Levinson

Recently published:

CensusSDC

Introduction: Census Transportation Planning Products (CTPP) are a set of tabulations of the American Community Survey (ACS) designed for transportation planners to estimate, calibrate, and validate transportation forecasting models. Statistical Disclosure Control (SDC) treatments were used for perturbing the ACS 2006-2010 microdata prior to generating the CTPP. The SDC approach maintains ACS respondent confidentiality when releasing aggregate work trip records, since perturbing selected data items reduced the disclosure risk that singly, or in combination, could be used to identify respondents. The table generator for the CTPP processed the SDC-treated microdata for a subset of the CTPP pre-specified tables. The SDC treatment process was developed from an extensive research study, National Cooperative Highway Research Program (NCHRP) 08- 79, which was undertaken in 2010-2011 to develop random perturbation procedures that would produce small area data (e.g., residence to workplace flows for areas approximately the size of Block Groups) that would not violate the Census Bureau’s Title 13 of the U.S. Code, under which the Census Bureau collects its data. Details about the research can be found in NCHRP (2011). During the NCHRP 08-79 research, Westat, under contract to the National Academy of Sciences, worked closely with the transportation planners as represented by the Transportation Research Board represented by the Transportation Research Board and Vanasse Hangen Brustlin (VHB), Inc.

The CTPP tables have been divided into two sets: Set A and Set B. The “Set A” tables were produced from un-perturbed data and “Set B” tables, were produced from perturbed data. The guidelines for generating the Set A and Set B tables were provided to the ACS operations (ACSO) staff. This general approach used perturbed data where tables would have been subjected to DRB disclosure rules, and used the original ACS five-year data for tables where there were no disclosure thresholds. It was designed to retain as much observed ACS data as possible.