Five questions about public transit, rail vs. bus, and gentrification

A producer for Real Money with Ali Velshi sent along five questions that Velshi might have asked during the interview about the Green Line. My talking points are below. Clearly this is too complicated for a three and a half minute interview.

1. So we often talk about investment in public transit as way to stimulate private development, make certain regions more attractive for businesses and residents. But is there a growing awareness that these projects don’t always improve life for all income classes? That they spur on gentrification can actually push out lower-income, working class residents?

Certainly gentrification is possible, however the case of the Green Line won’t see too much gentrification at first because there is so much vacant land in the corridor: parking lots and abandoned car dealerships, that can be redeveloped. Once the vacant land is consumed, this becomes a much more significant issue. The City and Metropolitan Council have a number of programs that have subsidized “affordable” housing in the corridor – most projects along the corridor in St. Paul have some public financial support.

It is important to remember that in Minnesota people don’t have a property right in low rents, and rent control is a bad idea that discourages investment.


2. As we just saw in the piece, the Twin Cities implemented a multi-faceted plan to help low-income residents and businesses along the Green Line. But there’s already been a hike in property taxes and 25% increase in median rental rates along the Green Line corridor. Did the city do enough?

Any accessibility increase will result in appreciations in property values. However, average prices have risen in the corridor in large part to the new housing (that is, new housing is more expensive (and nicer) on average than existing housing, pulling up average rents), along with improvements in the  economy in general.

New housing in the city will keep prices lower than they otherwise would have been in the absence of new housing, as it pushes out the supply curve. And if there were more housing supply added here, near rail stations, there is less elsewhere in the region than there would have been in the absence of the Green Line.

3. You worked before in transportation planning – if you had a billion dollars and were really setting out to help low-income residents, how would you have spent the money?

I would improve the bus system. Buses are more adaptable and flexible than rail. This matters because land use patterns change over time, and this kind of flexibility allows the transportation services to follow their customers.  Buses also have the advantage that they can “free ride” on existing roads, and so have much lower infrastructure costs. In just about all US cities buses serve more riders than rail system do, yet rail attracts the bulk of funding.

There are a number of improvements that can be made to buses, arterial Bus Rapid Transit systems provide higher quality, higher frequency, more reliable, and faster service, and that network should be built out and extended.

To be clear, the Green Line is the best rail project in the Twin Cities region, connecting two existing downtowns and the University along a relatively high-density urban corridor. The remaining extensions are more problematic, serving primarily suburban commuters.

Certainly for transit users, some investment is better than no investment, but that doesn’t mean we should support any investment that comes down the pike, instead we should try to design systems that best serve existing good transit markets – usually areas built before 1930, where the existing land uses are conducive to transit, rather than hoping to transform suburban green fields subject to the vagaries of speculative development.

4. If expanding bus systems would provide the most benefit for less money, why are so many cities focusing on building light rail systems? We’ve seen in cities like Portland, which has spent some $4 billion on light rail, street car, or commuter rail lines, spending on bus systems has actually dropped some 10 percent…

The people making and lobbying for rail investment decisions are generally not transit riders. They live in the suburbs and work downtown in offices and their mental model is everyone else does as well.  Most trips are not work trips. Most people don’t work. Most people who work, don’t work downtown. Most people who work don’t work in conventional office buildings. The decision-makers can’t imagine themselves riding on local buses (for a variety of reasons) and so design services for people like themselves rather than people who already use transit.

5. Did the Twin Cities really need to build a light rail? And can it really have the dramatic economic effects across all income levels that city officials hope for?

“Need” is a strong word. Given the federal government pays for half of transit capital investments, it was locally rational to build the Green Line. It serves users on the corridor better than previous  buses because it has a higher frequency, but that is a property of the frequency, not a property of it being a train.  It is important to note that much of the local funding for the lines comes from local sales taxes (which are regressive, that is the poor pay a greater share of their income for this than the wealthy), as well as a motor vehicle sales tax.

Westgate Station

Green Line / Green Lights

Suppose you have a train moving along (parallel to) an East-West (EW) signalized arterial.

Westgate Station
Westgate Station

Case 1: If the signals are pre-timed, and the timings are known in advance, the train should never have to stop for the signals (aside from emergency signal pre-emptions and other edge cases). Instead, the train should be able to adjust its speed so that it doesn’t have to stop. It might go at an average speed of say 10, 20, 30, or 40 MPH in order to ensure it hits a green light or better a green wave from whenever it departs a station. The train driver can be apprised of the optimal time to leave the previous (upstream) station, and the speed to travel to hit “green” lights.

Typical Signal Schedule and Traffic Flow Diagram, North-South across Market (1929)

Green waves have been around since the 1920s (See Henry Barnes’s autobiography: The Man with the Red and Green Eyes. Dutton. 1965. OCLC 522406). Static signs to tell travelers the speed of the green wave has been in standard use in some places (e.g. Connecticut Avenue in Washington, DC) for almost as long. Dynamic real-time signs which tell travelers what speed to adjust to to make the green wave has been recently patented and tested in simulation for automobiles: Always Green Traffic Control. The time is ripe for some carefully controlled field experimentation.

Still, pre-timing with information certainly doesn’t guarantee the fastest speed possible for the train, but it does guarantee no stops except at stations, which is good for a variety of reasons, including both travel time (avoid acceleration/deceleration loss), traveler comfort, energy use, and train wear and tear.

Case 2: If the signals are actuated, that is, their phase and perhaps cycle timings depend on traffic levels, and traffic “actuates” the signal, usually through an in-ground loop detector, transit signal priority from a fixed upstream distance should be sufficient to ensure the train doesn’t stop at a “red” light. The traffic light controller would know that a train was coming, and either keep the lights in the direction of the train green (if they are green), or change them to green and hold them, if it is currently red and the green is coming up. The train, knowing when the green will be on, should be able to adjust its speed (faster or slower) to make the green without stopping.

The distance that trains can currently notify a downstream signal controller is when they depart the upstream station, which is up to 1/2 mile or so (the spacing between stations). 1/2 mile at 30 mph takes 1 minute. With a cycle time of 2 minutes, and at least half the green time (1 minute) for the signalized arterial, a green can be guaranteed. If the light is currently red, it will be green within a minute. If it is currently green, it can be kept green for up to a minute. The worst case is it was just about to turn red and instead the green is extended for an additional minute. Alternatively, if it is currently green, a shorter than usual red phase can be inserted to clear the crossing traffic, before the light is turned back to green.

For traffic signals less than 1/2 mile downstream (say 1/4 mile) the warning time is only 30 seconds at 30 MPH. The same logic applies, but it is potentially more problematic as there is less lead time to adjust the timings, so the phase shortenings might be more severe. On the other hand, if more than 50% of the green time goes to the EW movement (say 75%) you aren’t really any worse off.

At 1/10 of a mile the warning time is less, but train departure from the station should be able to be coordinated with the light directly.

Case 3: But let’s say your traffic engineers are incapable of making this work. Should the train and its passengers suffer? This is where traffic signal pre-emption comes in. Most widely used for emergency vehicles, this potentially changes the sequence of phases, so maybe a phase is dropped (it doesn’t occur within the cycle, or within the usual place in the cycle).

This system does ensure that the vehicle requesting the pre-emption gets a green light as quickly as possible (safely turning the conflicting movements to a red phase) and thus can drive at as high a speed as possible. While trains should not need to stop at traffic lights with priority and speed adjustments, with pre-emption, they neither need to stop nor adjust their speed.

What could go wrong?

Pedestrians. Thus far we have been talking about a system with cars and trains. Pedestrians too can actuate signals, though “beg buttons“. These may function similar to vehicle actuators, in telling the traffic signal there is someone who wants to cross. The difficulty for priority or pre-emption is that a pedestrian phase may need to be longer since pedestrians take longer to cross the street than a vehicle does, especially if the street is very wide. So a pedestrian actuator may also extend the green time, in addition to calling for green time. This makes it more difficult to quickly change lights from red to green, since for safety reasons you can’t strand a pedestrian. This makes the ability to adjust train speeds in concert with the traffic signals more important.


Firetruck on University Avenue blocked by LRT train
Firetruck on University Avenue blocked by LRT train

Emergency vehicles. Emergency vehicle on emergency vehicle crashes are a known problem, and pre-emption may make it worse as firetrucks approaching a scene from two directions may both demand a green light, but only one gets it. The driver of one vehicle, not realizing he didn’t get the green (especially if he had the green as he was approaching), fails to yield. There are solutions to these problems.

Any of this will likely lead to additional delays for conflicting vehicle movements (cars making left turns or North-South traffic crossing our East-West arterial). With priority, this may even lead to extra delay for some vehicles on the parallel arterial who have been given a short green so the conflicting traffic can also get a short green before the EW arterial returns to green.

However the train usually has more people on it than are queued up at the other directions, so total *person* delay will generally be reduced.

For a variety of reasons, delay is bad (unless your goal is punishing drivers and air-breathers), we want to minimize total person time (or weighted total person time – recognizing long weights are more onerous than short weights) in the system (because time is money), and minimize pollution outcomes as well.

In short, the Green Line not getting green lights on University Avenue is a solvable problem. It should have been solved already. It eventually will be solved.

Further reading, with math: See Fundamentals of Transportation/Traffic Signals

Second Class

Transportation analysts typically favor bus over streetcar investments, although everything is conditional. We are puzzled by the fascination the economic development community (particularly the downtown business lobby) has for projects like streetcars, which in practice (i.e. in mixed traffic) are worse in providing transportation service than existing and easily enhanced technologies like the bus.

These folks will claim streetcars provide economic development benefits while bus will not (an empirically testable and falsifiable claim). I am speculating as to why they and their crowd hate-on the bus so much, but I think it has to do with the bus eco-system making them feel like second-class citizens. They themselves would not ride the local bus, and cannot imagine others like them would either.

1. New vs. Old

Anything new (and shiny) has some appeal, especially compared to old and run-down. We invent words to make old things sound nicer than they are (historic, classic, vintage, legacy, patina). While once streetcars were old and buses were new, the opposite is now (or soon will be) true.

2. Fast vs. Slow

Transportation is about speed (and frequency and  reliability). While speed has historically risen overall, speed (and reliability) on any particular transportation facility tends to decline with age. That is, once deployed, that is the fastest the system will go, and over time it will go slower. While there are occasional improvements, as infrastructure ages, it goes slower. Roads get more congested and more access points, reducing speed. Transit wears out, is shut down for maintenance, or slowed down in work zones, has stops added (more than they are eliminated). New is usually faster, but more importantly, limited access is faster. We can (and of course did) build a new mode that is overall slower (though more frequent) than existing transportation modes it replaced, but that is harder to justify, so it is always pitched as faster, even if in contradiction to the facts.

3. Amenities vs. amenity-free

Please Check Schedules
Please Check Schedules

People like amenities, features, gadgets. Some of them are genuinely useful, like the LRT station variable message signs which say “please check schedules”, er, like the LRT station variable message signs which are supposed to tell you how many minutes until the next train. Shelters and heat are nice in bad weather. Pre-paying saves time. Working signs can provide useful information which relieve anxiety

4. People like us vs. people not like us

People like to live with people who are like them, or their economic “betters”, who raise their status by association. This process explains economic sorting in real-estate markets. It should be no surprise that people want to ride with people who are like them, or their economic “betters”, who also raise their status by association, and don’t want to ride with others.

This “people like us” phenomenon also leaks into the taxi vs. Uber/Lyft debate. Uber and Lyft drivers are more like “us” (if “us” is upper middle class folks and above) than your typical taxi driver.

System Dynamics

The decision of the “choice rider” (as opposed to what was once unfortunately called “captive riders” in the field, and then “transit dependent”, and now “transit reliant”) to ride the bus thus depends on whether other similar people ride the bus. Presumably they are making the same kind of decision. They are not considering the positive externality (virtuous circle) that their riding the bus increases the likelihood someone like them rides the bus (and their not riding the bus lowers the same likelihood (in a vicious circle)). Like any positive feedback system, this is both a cause and an effect.

The choice rider doesn’t ride because of 1, 2, 3, and 4, and their not riding makes 4 even worse. The lack of choice riders weakens the political constituency for improvements to 1, 2, 3.

So try to tell people at dinner party they should willingly ride on an old, slow, amenity-free service with people who they otherwise would not associate with, even though they don’t have to and can afford alternatives, and they will smile and turn to the next person. They don’t want to feel second-class, or to feel guilty about not wanting to feel second-class. All too-often, this mode is “bus”, especially in cities without historic, classic, and patina-ed rail systems.

Instead tell people who have a choice that they can ride on a mode that is new, fast, with amenities, and with people who are like themselves, and they might consider it from time to time, and more regularly if it is cost and time-effective. This mode need not be rail.

Unlike a new, fancy, and expensive rail system, existing buses are now the opposite, old, basic, and cheap. There is nothing technically preventing the bus and bus stop from being nice, (basically as nice as a brand new train and rail station, but usually a lot less expensive) but the lack of willingness on the part of the public from doing so.

Bus transit has more than an image problem. Its image problem results from the reality of services, which are in part due to relatively less investment than rail services get, because it has an image problem. It is a vicious circle.

Access Across America Pooled Fund Webinar

Access Across America is a state-of-the-art multimodal accessibility evaluation for transportation system performance management and planning. The webinar (recorded August 6, 2014) featured an overview of the Access Across America project and examples of accessibility calculation results, information about the request for participation in the Access Across America Pooled Fund project, and a question and answer session.

(Pooled Funds are the “Kickstarter” for transportation research, where participants are usually, but not only, state DOTs – notably this process was developed in transportation some 20 years ago, much earlier than Kickstarter formed … yet another example of transportation exporting technologies to other sectors).

Watch webinar


Pooled Fund Proposal Draft

Buses and railroad crossings

Buses are required by law to stop at railroad crossings (except where exempted, such as the light rail tracks on University Avenue in the Twin Cities). This is for safety reasons, the law was implemented in Utah for school buses after a terrible accident. The Deseret News reports:

DeVon Andrus of Cedar City wrote, “I endorse everything said about the safety on school buses. However, there are a few of us who remember a day in December 1938 when the worst school bus accident in the history of the United States occurred in Sandy, Utah. As a result of this accident, laws were passed in every state regulating bus travel when crossing railroad tracks. … Bus drivers were required to stop and open the door, look both ways and listen before crossing the tracks. …”

I know “safety first” and laws like this help keep us all alive, but sometimes they are applied too much.

Railroad Crossing at Franklin Avenue SE
Railroad Crossing at Franklin Avenue SE

There is a railroad crossing on Franklin Avenue in SE Minneapolis which is part of a spur, which used to have very few trains, and now has approximately none since the building it served (Bemis Products) is being converted housing (Brickhouse Lofts). Yet the tracks have not been removed, since the railroad (I suppose) might want to use the spur as a siding to store railcars sometimes.

Dozens of times each day school buses and Metro Transit buses and Metro Mobility buses decelerate, stop, look for non-existent trains, and accelerate again. This wastes time and energy, increases the wear and tear on vehicles, and pollutes the environment (with associated public health effects that probably exceed the safety benefits in these cases).

Is there a way to either (a) get railroads to pull up their unused track and abandon the right-of-way in a more timely fashion, (b) exempt more low volume tracks from the stopping requirement? [Clearly "exempt" signs are allowed, they just don't seem to be implemented as widely as they might be.]

Are our roads really more congested | StarTribune

Tim Harlow, of the StarTribune’s The Drive column asks if “our roads are really more congested?” and interviewed me:


Of course, almost every time a report on traffic comes out, it makes the headlines. But how do we make heads or tails out of them when they seem to contradict one another?

“They are not necessarily contradictory,” said David Levinson, a professor of civil engineering at the University of Minnesota. “They all have different data, but they are measuring roughly the same thing.”

The differences can start with how the report makers define congestion. MnDOT defines congestion as traffic flowing at speeds less than or equal to 45 miles per hour. TomTom defines it as increased travel time when compared to free-flow conditions.

The data used to compile reports comes from different sources, too. MnDOT uses loop detectors embedded in the pavement while INRIX uses GPS data. Another difference is that the INRIX report looked at traffic volume and delays while MnDOT’s congestion report details the location and percentage of freeways experiencing daily congestion.

New business or housing developments can alter traffic flow in areas, making roads that were adequate suddenly become packed, creating the perception that congestion is getting worse.

“You might see more this year because the economy has picked up, but generally it has been flat and has been for a while,” Levinson said. “If it gets too bad, people will change their behavior. … There are limits on how bad the congestion can get.”

by David Levinson


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