Category Archives: Traffic Engineering

Open Access Article: Spatial modeling of bicycle activity at signalized intersections | Institute of Transportation Studies Library

Open Access Article: Spatial modeling of bicycle activity at signalized intersections

Biking at Grand/Halsted/Milwaukee (3 of 4)

This week is Open Access Week. What’s Open Access? Here is a not very brief overview by Peter Suber. UC Berkeley also has an Open Access Initiative to help open up your research and data. 

In the spirit of Open Access Week, here’s an interesting article from an open access journal – The Journal of Transport and Land Use. Go check it out and peruse the articles. No need to depend on your institution’s sibscription because it’s free to the public! (Thanks open access!)

In “Spatial modeling of bicycle activity at signalized intersections“, Jillian Strauss and Luis F Miranda-Moreno look at the built-environment and cycling. 

This paper presents a methodology to investigate the link between bicycle activity and built environment, road and transit network characteristics, and bicycle facilities while also accounting for spatial autocorrelation between intersections. The methodology includes the normalization of manual cyclist counts to average seasonal daily volumes (ASDV), taking into account temporal variations and using hourly, daily, and monthly expansion factors obtained from automatic bicycle count data. To correct for weather conditions, two approaches were used. In the first approach, a relative weather ridership model was generated using the automatic bicycle count and weather data. In the second approach, weather variables were introduced directly into the model. For each approach, the effects of built environment, road and transit characteristics, and bicycle facilities on cyclist volumes were determined. It was found that employment, schools, metro stations, bus stops, parks, land mix, mean income, bicycle facility type (bicycle lanes and cycle tracks), length of bicycle facilities, average street length, and presence of parking entrances were associated with bicycle activity. From these, it was found that the main factors associated with bicycle activity were land-use mix, cycle track presence, and employment density. For instance, intersections with cycle tracks have on average 61 percent more cyclists than intersections without. An increase of 10 percent in land-use mix or employment density would cause an increase of 8 percent or 5.3 percent, respectively, in bicycle flows. The methods and results proposed in this research are helpful for planning bicycle facilities and analyzing cyclist safety. Limitations and future work are discussed at the end of this paper.

The full article can be found here

The price of anarchy – on the roads and in football

Colleagues at the University of Minnesota write:

Skinner, B and Carlin, B (2013) The price of anarchy – on the roads and in football Significance 10(3) pp. 25-30:

“City traffic can sometimes move faster when a road is closed. A football team can sometimes play better without its best player. The two are linked. Anarchy, say Brian Skinner and Brad Carlin, is freedom to be counterproductive.”

[I am not sure I would interpret I-35W as a Braess's paradox example, strictly speaking it fails the test, but its advantages were a lot less than might have been thought, and certainly many people were worse off after it opened, if not overall. The general analogy to sports is interesting though.]

Seven hours in New York City

I was briefly in New York yesterday. By briefly I mean I left Minneapolis when it was daylight, and returned and it was still daylight. This is of course much easier to accomplish when you are near the summer solstice, but still it suggests the technical feasibility, though definitely not the desirability, of cross-continental commutes.

On the Minneapolis side, things went very smoothly. I left my house at 5:45 AM, caught the bus at 5:53, was at the LRT by 6:00, caught the ~6:03 LRT to the airport and was there by 6:20. Security was quick, the weather was good, the 8:05 flight was on-time.

Some comments on transportation in America’s largest city.

For a city with so many airline passengers, and presumably airline profits, some of the airport terminals (JFK Terminal 2) are still quite dumpy (Yes there is a plan to fix this). One would think that if there were competitive owners of each different airport (and each terminal), they would have to compete for customers (both passengers and airlines) by differentiating quality (presumably upwards). Though there has been some terminal modernization, New York is far behind the rest of western (and eastern) civilization in this arena.

Second, there is not good transit access from the airports to the City. New York, with the US’s largest subway system has had more than 50 years since the dawn of the jet age to connect its airports to its transit system successfully, and seems to have failed to avail itself. (I am aware of JFK’s AirTrain, it seems to require a separate charge from the transit system and a transfer, surely someone could figure out how to bundle that. It also required taking the subway with 33 stops to my Midtown destination). This is not an unknown problem, and solutions are proposed for LaGuardia (via Bus, apparently the train proposal was shelved) and JFK (at about $10B, which seems excessive, but this is NYC).

At any rate, someone else was paying for my surface transportation, so I was in a car. (Which I realize makes me part of the problem, not the solution, but also gives me the perspective of enlightened commentators such as Dorothy Rabinowitz. Yet I did not notice any problems with CitiBikes on my brief stay. There were some bicycles darting in and out of traffic, but that was because cars were not moving and bikes could). On the way in I also got to hear the political philosophy of my driver (a well-educated Russian immigrant from over 30 years ago), who is probably best described as a Peter King Republican, which probably would not have happened on a subway train. The driver seemed to be of the belief that bus lanes were a bad idea because they delayed cars, and in general was opposed to the Bloomberg administration. He also thought most of the works were badly managed and timed poorly (this I agree with) so the Unions could flex their power, and that trucks should only enter the city at night. Of course where you stand depend on where you sit.

Third, New York has far more street traffic congestion than it should. Of course it is crowded, and it probably shouldn’t build more highways, but it doesn’t manage scarce roadspace the way a well-managed city would.

  • On the way in to the city, one of the lanes on the Queens Midtown Expressway was blocked so someone (1 person) could sweep the shoulder, with a broom, in the middle of the day. To be charitable, maybe there was recent broken glass that required cleaning, but this seemed far more substantial cleaning than the debris from a fender-bender. The queues formed by the lane closure were several miles in length.
  • Why is on-street parking permitted in the middle of the day on both sides of the street on major congested streets (37th Street)? This seems to be more than loading/unloading and more than temporary construction crews.
  • And why is don’t block the box not enforced. This would seem a perfect opportunity to use red light running cameras to ticket people who block cross-traffic on the red light.

This is even before considering what economists normally think about when they say pricing, some form of congestion charge, which has been proposed and not implemented because the winners could not bring themselves to pay off the losers.

Fourth, why is there congestion at the airport on a clear day with as perfect weather as one could ask for? Leaving LaGuardia, we boarded the plane on-time and the plane was 17th for take-off with about 40 minutes of ground wait. We landed “on time”, meaning the airline (Delta) built in 45 minutes of ground delay into the schedule to ensure “on time” arrivals. If the schedule is such that the same flights are repeated daily (an approximation), then our plane would take off at the same time every day regardless (unless it was worse due to weather). Which means, we could have been scheduled a half-hour later and not waited in the plane on the ground. This is a simple coordination problem that could be solved with reservation pricing. I suspect this is a problem because there are competing airlines which want to offer the same departure time (~6:45 pm), but a monopoly airport. In a different airport a dominant (hub) airline might internalize the delay costs. See Daniel (1995) on Congestion Pricing and Capacity of Large Hub Airports: A Bottleneck Model with Stochastic Queues.

County presents scenarios for Franklin/East River Parkway remake | Bridgeland News

From the Bridgeland News: County presents scenarios for Franklin/East River Parkway remake
From the article:

“Two suggestions bordered on the Swiftian: One was a modest proposal to remove all traffic control from the existing intersection. “When those signals are out, that intersection functions fairly well,” stated one man.”

I was “one man”.
The official alternatives are available here:
Project website
My letter (sent to the team and local public officials) clarifying what I am thinking about, which I sent to the project team is below:

Jim,
Thank you for hosting the public hearing on the Franklin Ave/27th Street/East River Road intersection. I mentioned the meeting you should consider a shared-space concept (including perhaps a simple roundabout, but without all of the complex signage, separation, etc.) , the ideas I have in mind are illustrated here:

http://www.shared-space.org/

The advantage is that it could cost much less, and could be easily tested (put some covers on the signals, take down the signs, and put up some warning signs telling people upstream they are approaching a new environment, without requiring full reconstruction.
A video showing some of the ideas is here:

AND

(especially at 5:00 into the second video)
I recognize the idea may appear radical to traditional engineering practice, but I think it is worth giving full consideration to, especially on a site like this with no obvious inexpensive solution, with a mix of commuter and parkway traffic, bicycles, and pedestrians, a desire to minimize land taking, and a desire to calm traffic.
Please let me know if you have any questions.
— David

Finally, in addition to having a personal interest in the intersection since I use it daily, I also supervised a Master’s Degree paper: Evaluation of a Roundabout at a Five-Way Intersection: An Alternatives Analysis Using Microsimulation on the intersection by Reuben Collins, which recommended a roundabout.
Unfortunately, judging by their response to comments, the study team clearly has not yet grokked the possibilities of alternatives to conventional (i.e. US standards-based) design, and intends to overbuild and oversign the location.