Sunday, April 13, 2008

Walking Between the Lines

While much of this blog's writing is devoted to transit, I try to focus on other forms of alternative transportation from time to time, and walking is one strongly correlated to transit use. Earlier this year after being struck by a car while crossing the street in suburban Washington, I penned a post on pedestrian safety. I encourage you to read it as an introduction to the statistics of pedestrian accidents and street design. Today, however, I want to focus more on pedestrian behavior and corresponding planning and policy decisions.

A recent post at the WashCycle reported on a pedestrian and bicycle sting in the U Street neighborhood in the District. Enforcement is a good thing, although I would question the end result of this sting operation. A more productive approach, it seems, would be to inquire as to why pedestrian and bicycle violations are a problem. What role does street design play? What role does urban design play?

The Insurance Institute for Highway Safety (IIHS) reports that only 23% of fatal pedestrian crashes occur at intersections--the vast majority occur at mid-block locations. These data suggest that the higher fatality rates occur because drivers are traveling at higher speeds and do not expect to stop.

In a somewhat difficult lesson in public relations, the City of Atlanta Police Department got egg on its face after an officer tackled a renown British historian for jaywalking across a downtown street. No less than 5 police officers were present for the arrest, which made headlines in the UK as well as in Atlanta. After 8 hours in jail, the charges were dropped. The case in and of itself is not important for this discussion, the context is, however. The historian was crossing mid-block between two hotels sharing a conference. Urban design clearly played a role in this because both hotels have their entrances in the middle of the block. In order for people to travel between the buildings, they must walk 200 feet to the nearest intersection, cross Courtland, and walk 200 feet back up the street. The shortest distance is bisected by five lanes of one-way traffic on a freeway-fed urban arterial.

This particular situation could be improved by designing buildings to have entrances on corners or to include pedestrian bridges. Additionally, studies show that converting one-way streets to two-way streets has the effect of slowing traffic and reducing pedestrian crashes. And while Atlanta clearly has a long way to go to become pedestrian friendly, the strict enforcement applied to the Briton reveals the bias reported by Richard Retting, New York City DOT's Chief of Safety in a 1987 publication.

Retting mentions the need to exchange blame (which he claims is often placed on the victim) for pedestrian crashes with design of pedestrian facilities based on human factors. Human Factors Analysis investigates accidents where human error is at fault so as to better design safety systems. Retting reports on one safety initiative on Queens Boulevard which reduced pedestrian deaths by 44% and severe injuries by 77%.

In a 2003 article in the American Journal of Public Health Retting and Ferguson, report on different measures used to reduce pedestrian crashes (Retting, R.A.; Ferguson, S.A.; and McCartt, A.T. 2003. A review of evidence-based traffic engineering measures to reduce pedestrian-motor vehicle crashes. American Journal of Public Health Vol. 93 Issue 9). Their analysis reveals some interesting strategies to address the issue.

The importance of traffic calming as a method of reducing pedestrian crashes is also stated in the report. The findings show that crosswalks alone do not cause drivers to stop for pedestrians when they are in an unsignalized area. In fact, installation of crosswalks without other forms of traffic calming (such as refuge islands or flashing lights) can actually increase crash rates in some cases.

The aforementioned report divides the process of making places safer for pedestrians into three categories. The first is to reduce vehicle speeds. The second method separates pedestrians from automotive traffic. Finally, the last approach calls for increasing the visibility of pedestrians.

Over half of pedestrian fatalities occur at night. One study showed a 59% drop in nighttime crashes after the installation of better lighting at crosswalks (daytime crashes remained the same). Installation of sidewalks also has a major effect on safety, especially in residential neighborhoods, where areas without sidewalks had pedestrian crash rates 2 times higher. Additionally, moving bus stops to the far side of intersections significantly reduced accidents stemming from pedestrians crossing in front of the bus.

Their study also showed that automated pedestrian detection systems reduced jaywalking by 52 to 88%. And while automated pedestrian detection is certainly an improvement over push-button activation (pedestrian actuation), it's not as good as an automatic walk signal. The main function of the pedestrian actuation button is to extend the green cycle to allow pedestrians more time to cross. Unfortunately, in most situations, unless the button is pushed several seconds before the light cycles, pedestrians only see "don't walk."Even if a walker arrives the second the light changes, he or she has to wait for an entire cycle of the light or risk crossing without warning of when the light is about to change to yellow (by a flashing "don't walk"). Since there are only a given number of seconds in the day however, traffic engineers make many traffic signals more efficient by only changing them when cross-traffic or pedestrians are present. In high pedestrian volume areas, however, it makes sense to have an automatic walk every time. After all, imagine if cars had to contend with red lights that were always red (in all directions for 2 minutes before a green light appeared. Push-buttons are often inconvenient, inaccessible (especially to bicyclists and the handicapped), or out of the way.*

*Note: I am not proposing the removal of 'hot-response' buttons at pedestrian crossings. These buttons, when pushed, immediately or quickly change the traffic signal to yellow, then red, giving pedestrians the right of way.

Above, a pedestrian actuated push button
at East-West Highway and Belcrest Road

To investigate the impact of pedestrian actuation on traffic timing, I measured a signal near my 'home' Metro station. One would think that a red light near a metro station (actually in this case the entrance for buses, cars, and pedestrians) would have an automatic walk, but it does not. While my survey is not scientific, I think it represents a good example of how signal timing plays a role in pedestrian safety. The intersection I measured is located in Prince George's County, at East-West Highway and the Metro Entrance. Without the use of the pedestrian actuation button, traffic leaving the Metro station had a green light for about 20 seconds, although that was longer if cars were still behind the stop bar after 20 seconds. With the push button, the green cycle was extended by 5 seconds, and pedestrians were given an advance walk** signal of 5 seconds, effectively lengthening the red time for East-West Highway by only 10 seconds. Since the presence of additional automobiles lengthened the green more than 10 seconds while I was there, it seems unreasonable not to have an automatic walk signal (and a minimum green of 30 seconds) every time, at least at this location.

**An advance walk signal (or Leading Pedestrian Interval, LPI) occurs when the walk signal precedes the green light, during which time all vehicle signals are red. Retting reported on a study showing a 95% reduction in pedestrian crashes at intersections after implementation of the LPI.

Another instance of light timing which I have observed also seemed to increase pedestrian safety. While I am unaware of any studies about this, the City of Atlanta moved the protected and protected-permissive left turn phases of several east-west streets onto northbound one-way streets to the end of the light cycle (lagging left). In this case, it meant that queuing pedestrians didn't inadvertently walk into the path of cars with a green arrow. Instead, by the time cars got a green left-turn arrow, most pedestrians had already cleared the area, and those approaching the intersection were more likely to wait. I don't know if Atlanta's motive was pedestrian safety, but from a pure observational standpoint, it seems to have had that effect.

Studies show that pedestrians are far more likely to be struck by turning vehicles, especially left-turning vehicles. One strategy which I have yet to see implemented, but that I think might have an impact on pedestrian behavior is a protected/permissive left warning. Essentially, a sign above the walk/don't walk signal that is illuminated when cars have a green turning arrow that conflicts with the pedestrian movement in question. This would let pedestrians know that they need to wait. Additionally, push-buttons could serve to illuminate a sign for automobiles when pedestrians are present. Today's automated pedestrian detection technology already allows for the automated extension of a green light for slow pedestrians. That system could be used to warn drivers as well.

Another proven strategy is the refuge island. This allows pedestrians a place to wait while crossing multi-lane streets. Retting's study reported that pedestrian crash rates on streets with medians were half that of streets without medians. In addition to giving pedestrians a place to wait, they also shorten the perceived distance of the crossing, and especially when coupled with curb extensions (bulbouts), reduce traffic speeds. Compare the pictures below from a pedestrian standpoint.

Crossing Route 1 at Hartwick in
downtown College Park, the median
stops shy of protecting pedestrians,
especially from u-turns

Crossing Belcrest at East-West
in Hyattsville, pedestrians can
stop halfway across the street

With gas prices and transit ridership increasing at unheard of rates, it seems pertinent for planners and policy makers to improve the urban/suburban environment to encourage alternative modes of transport. One such mode is walking. Annually in the United States, 6000 pedestrians are killed in car crashes, and design plays a large role. While I have just touched on a few key issues, it is clear that more needs to be done. For far too long, pedestrians have not been considered in the design of our transportation infrastructure and community design. It is high time for that deficiency to end.

I was happy to hear earlier this year that a bill was introduced into the US Senate to "ensure that all users of the transportation system...are able to travel safely and conveniently on streets and highways." Senate Bill 2686 (FAQ) was introduced March 3, 2008 by Senator Tom Harkin, a Democrat from Iowa. Thank you Senator.

No comments: