Tag Archives: crosswalk

Scaling up and scaling down

New York bicycling advocate Steve Faust has stated that some ways of accommodating bicycling do not “scale up” — that is, they work with small numbers of cyclists, but less well with larger numbers.

His central complaint is that use of roadways with no special bicycle facilities, according to the conventional rules of the road, does not scale up well.

I might put that a bit differently. After all, more cyclists need more room. Mass rides such as New York’s own 5-Borough Tour avoid special bicycle facilities and occupy the entire width of Manhattan’s multi-lane avenues. Motor vehicles are excluded while these rides pass through. Interaction within the group of many thousands of cyclists is for the most part according to the conventional rules of the road, and falls short only in that many of the participants are inexperienced.

On roadways carrying both cyclists and motorists, cyclists inconvenience motorists when the motor traffic could go faster — that is, when there are many cyclists and few enough motorists that they could travel unimpeded, if not for the cyclists. Motorists inconvenience cyclists when motor traffic is congested, and stopped or traveling slower than cyclists might want to go. Level of service always declines as a road becomes more congested, and it declines faster when vehicles have differing speed capabilities.

On the other hand, there also are situations in which operation as intended does not scale down to smaller numbers.

Motorists are more likely, for example, to yield to a crowd of pedestrians than to a single pedestrian.

Another example is the leading pedestrian interval: the walk signal goes on a couple of seconds before motorists get the green light. The leading pedestrian interval is intended to get pedestrians moving out into the intersection before motor traffic can begin to turn across a crosswalk, encouraging motorists to yield to the pedestrians. The same approach is used sometimes on bicycle facilities, for example on the Boulevard de Maisonneuve bicycle sidepath in Montréal, Québec, Canada. But a leading interval only works if there is someone waiting to cross when the signal changes. With smaller numbers, so the first pedestrian or bicyclist reaches the crossing after the motorists get their green light, the leading interval’s only achievement is slightly to reduce the capacity of the intersection.

The same issue can occur with any “conflict zone” with poor visibility as users approach, including the “bike box” or bicycle waiting area ahead of the stop line for motorists at an intersection. Once one cyclist is in a “bike box”, a motorist is unlikely to move forward, because that would require running over the cyclist. Therefore, the bike box is then safe for the entry of other cyclists, at least into the same lane in which the first cyclist is waiting.

The”bike box” works as intended when there are large numbers of cyclists so the first one arrives well before the traffic signal turns green.

If there are few cyclists, so the first one is likely to arrive just as the traffic signal turns green, then there is the potential for a right-hook collision, or a motorist’s colliding with a cyclist swerving into the bike box.

Safety requires that there be enough cyclists that early-arriving ones block the way of motorists, or at least alert the motorists that others may arrive. This safety factor does not scale down to small numbers.

Research in Portland, Oregon shows that only 5% of bicyclists swerve into the bike box when they are first to arrive; about 35% if they arrive later. The reluctance of the first-arriving cyclist reflects risk avoidance to some extent, due to not knowing when the traffic signal will change, but also that the swerve lengthens the cyclist’s trip — none of the Portland bike boxes are designated for left turns. The later-arriving cyclists are to some degree protected by the arrival of the first one, but also they either have to wait behind or move over to the left of that cyclist, into the bike box.

“Safety in numbers” claims become rather interesting when such issues are considered.

The design challenge is to achieve efficiency and safety of all travelers, regardless of whether numbers are large or small.

On the Dangerous by Design report

I’m commenting briefly on a report about walking conditions in the USA at

http://t4america.org/docs/dbd2011/Dangerous-by-Design-2011.pdf

which has been cited in a New York Times article today.

I regard this report as generally good in its description of walking conditions. It is not intended to be about bicycling,

However, several of the partner organizations listed at its start — among them, America Bikes, the National Complete Streets Coalition, the Rails to Trails Conservancy — concern themselves with bicycling, and bicycling appears here and there in the report as an aside. I’ll make the following points:

  • The report repeatedly refers to “streets designed for traffic, not for pedestrians”. This is a wording problem and a conceptual problem too. Pedestrians are traffic. It would be appropriate to say “streets designed for motor traffic, not for pedestrians”.
  • Page 13 includes the wording “Metros such as Boston, New York and Minneapolis-St. Paul are investing to build a well-developed network of sidewalks and crosswalks and already have many people walking and bicycling.” Pages 7, 29 and 36 all include the wording that “we need to create complete networks of sidewalks, bicycle paths and trails so that residents can travel safely throughout an area.” A complete network for bicycling will be mostly on streets, and partly on trails, but should generally avoid sidewalks.
  • Page 30 gives a before-and-after comparison, describing a street as having “no safe space for bikes” though the street had wide lanes where motorists and bicyclists easily could coexist. Then, narrowing the lanes and adding bike lane stripes is supposed to have created safe space, when it actually removed space and encouraged unsafe maneuvers (motorist turning right from the left of bicyclists, bicyclists overtaking on the right). The street needed repaving, and better sidewalks and crosswalks, to be sure.
  • Bicycling issues are very different from walking issues. An area that is poor for walking due to the lack of sidewalks and crosswalks can be good for bicycling. Confusing the two modes and the ways to accommodate them leads to poor planning and design decisions.
  • I am pleased to see the Boston area, where I live, described as having the very best record of pedestrian safety of any city rated in the report. Strange, isn’t it — the Boston area has repeatedly been derogated as supposedly having the nation’s craziest drivers. Also, Boston has been on Bicycling Magazine’s “10 worst cities” list until recently, when its city government finally got interested in bicycling. Boston is by no means a bad place to ride a bicycle compared with many other American cities, and the city’s efforts may be described as having mixed success, but that’s another story.

Confusion at crosswalks on multi-use paths

The crosswalk on a multi-use path has a mixed identity, unless the crossing is signalized. Motorists must yield to pedestrians in the crosswalk, but on the other hand, a stop sign facing the path normally means that cyclists yield to traffic on the road. It is certainly crucial for cyclists to slow, sometimes even stop, to check for cross traffic, and for motorists to yield to cyclists already in the crosswalk, but, again, the stop sign would normally indicate that the cyclists must yield. Confusion arises when a cyclist stops and intends to yield, then a motorist also stops — “you go first.” “No, you go first.” This causes unnecessary delay for both when the cyclist intended to cross behind the motorist, but now must wait until the motorist stops. Danger arises in addition when a motorist in a more distant lane does not stop. That motorist’s vehicle may be concealed from the cyclist by the one stopped in the closer lane — leading to the classic and ineptly-named “multiple-threat” collision. (Two crossing vehicles are involved, but the one in the nearer lane is stopped and does not pose a threat.) There would potentially be legal confusion as well in case of a collision, as both the motorist and the cyclist might claim that the other should have yielded!

Dr. Furth’s and his students’ plan for South Brookline

On March 14, 2011, I attended a meeting in Brookline, Massachusetts, a suburb of Boston. At that meeting, Dr. Peter Furth of Northeastern University, and some of his students, gave a presentation on proposals for street reconstruction and bikeways in the southern part of Brookline.

Proposed treatment for West Roxbury Parkway

Proposed replacement of two two-lane one-way roadways with shoulders by a narrowed two-way roadway without shoulders and an adjacent multi-use path; Newton Street (up the embankment at the left) to provide local access only.

Most of the streets in the project area are fine for reasonably competent adult and teen cyclists to share with motorists, though one street, Hammond Street, is much less so, with its heavy traffic, four narrow lanes and no shoulders. I do agree with a premise of the presentation, that bicycling conditions could be improved, but I suggest different treatments, such as conversion from four lanes to three, with a center turn lane which becomes a median at crosswalks, also freeing up room at the sides of the roadway for motorists to overtake bicyclists.

Please read through this introduction before looking through the photo album I have posted with images from the meeting presentation, and drawings which were taped up in the meeting room.

My Concerns with the Proposal

Generally, I am concerned with the hazards and delays — and in winter, complete lack of service — which the proposal introduces for bicyclists, and with the blockages and longer trips it introduces for motorists, resulting in delay and in increased fuel use and air pollution. Some specifics:

  • The proposed system of narrow two-lane streets and segregation of bicyclists onto parallel paths makes no provision for the foreseeable increasing diversity of vehicle types and speeds as fuel prices rise. This trend can only be managed efficiently and flexibly with streets that are wide enough to allow overtaking.
  • Proposed paths are on the opposite side of the street from most trip generators, and many movements would require bicyclists to travel in crosswalks, imposing delay, inconvenience and risk for bicycle travel on the proposed route and on others which cross it. Small children would not safely be able to use the proposed routes unless accompanied by an adult, same as at present.
  • The proposal would further degrade or eliminate bicycle access in winter, because of the proposed 22-foot roadway width, and because the proposed parallel paths could not be kept ice-free even if they are plowed.
  • Though intersections are key to maintaining traffic flow, the proposal puts forward an incomplete design for most intersections and no design for some of them.
  • The narrowed streets provide no accommodation for a vehicle which must stop while preparing to turn left into a driveway, or to make a delivery, or to pick up or discharge passengers, for bicyclists who must travel in the street to reach a destination on the side opposite the path, or for bicyclists who wish to travel faster than the path allows.
  • The proposal includes no discussion of improvements to public transportation, which would be key to reductions in congestion and fossil fuel use. There are no bus turnouts, although Clyde and Lee Streets are on an MBTA bus line, school buses use the streets in the project area, and additional bus routes are foreseeable.
  • The proposal includes a 12-foot-wide service road along Clyde and Lee Street, part of which is to carry two-way motor traffic along with bicycle and pedestrian traffic. At times of heavy use, 12 feet on the Minuteman Bikeway in Boston’s northwestern suburbs is inadequate with only pedestrian and bicycle traffic. 12 feet is not wide enough to allow one motor vehicle to pass another. Larger service vehicles (moving vans, garbage trucks etc.) could access parts of this service road only by backing in, or by driving up a curb and across landscaped areas. These vehicles would completely block other motorized traffic on the service road.
  • The proposal is expensive because it requires tearing up every one of the streets in order to narrow it, not only construction of a parallel path.

Confusion in the Presentation

There also was confusion in the presentation:

  • North is confused with south, or east with west in the captions to several photos. Due to the confusion, some photos show a path on the opposite side of the street from where the plan drawings place it.
  • Some items in the illustrations are out of proportion. In one illustration (the one near the top in this post), a two-lane arterial street is only 10 feet wide, based on the height of a Segway rider on an adjacent path, or else the Segway rider is 12 feet tall, riding a giant Segway.
  • Other details are inconsistent, for example, showing a sidewalk in a plan drawing, but no sidewalk in an image illustrating the same location.
  • There is confusion about location of some of the photos. Some cross-section drawings are shown without identification of the location in the plans. The location of one cross section is misidentified.
  • The proposal makes unsupportable claims about safety.

There also is an ethical issue: in their presentation, the students have appropriated a number of Google Street View images without attribution — a violation of copyright and of academic ethics. (Furth’s students also plagiarized photos from my own Web site for a different presentation, but I digress.)

Overview and Conclusions

The proposal generally attempts to make bicycle travel a safe option for children and for people who are new to bicycling. It fails to accomplish that, due to problems with access across streets to the proposed pathways. It also adds complication and delay for motorists and for the majority of existing and foreseeable bicycle users. It degrades and sometimes eliminates bicycling as an option in the winter months, and it pays no attention whatever to public transportation.

I have no objection to construction of a path in the parkland adjacent to the streets in the project area, but the proposal also works to enforce the use of the path by reducing the utility of the road network for bicyclists as well as for other users.

I do think that street improvements are desirable, and on one street (Hammond Street) a high priority to improve bicycling conditions, but these improvements can be achieved mostly through restriping, without the massive reconstruction, or rather, deconstruction, that has been proposed.  This narrowing the roadways is intended to increase greenspace, and also  apparently to reduce speeding, but the proposal goes way overboard in reducing capacity, convenience and flexibility. There are other options to reduce speeding, most notably enforcement and traffic-calming measures which affect speed without decreasing capacity.

The large multi-way rotary intersection of  Hammond, Lagrange and Newton Streets, West Roxbury Parkway and Hammond Pond Parkway is the one place where I consider reconstruction to be a high priority.

Education also is an essential element of any attempt to make bicycling safer and a more practical option.

Larger Contextual Issues

Long-run issues of energy cost and availability raise questions about the viability of sprawled suburbs whose residents are dependent on private motor-vehicle travel.

South Brookline is more fortunate. It is a medium-density residential area of single-family homes, only about 5 miles from the Boston city center and also only a few miles from the Route 128 corridor, a major employment concentrator. Schools, places of worship, parklands and shopping are closer than that. Bicycling can and should have a role here, but for many people and many trips, it is not an option, due to age, infirmity, distance, and the need to transport passengers and goods.

South Brookline could benefit from a comprehensive transportation plan, including strengthening of public-transportation options and maintaining arterial roads with capacity for varied existing,  foreseeable and unforeseen uses.

Developing such a plan requires skills, resources and time beyond what I can muster, and so I’ll not attempt that here.

Now, please move onto the photo album.

Davis Planners and Advocates Opine on Sidepaths

This post supplements my previous post linking to documents about Davis bicycle facilities. Please bear in mind that Davis was the first community to introduce bike lanes in the USA, and that its bicycle program strongly favors conventional bike lanes, which are separated from the adjacent lane only by a painted stripe. However, I have found that the Davis documents uniformly and strongly recommend against bike lanes behind barriers or parked cars. Not only that, the recent warnings are more definite than the early ones. Some quotes, starting with the most recent and working backwards in time:

Theodore Buehler, Fifty years of bicycle policy in Davis, CA (Master’s thesis, 2007). See pages 50 ff., “Lane location relative to motorized traffic”.

The early experiments included three different types of bike facilities (see examples at the top of this section):

  1. bike lanes between car lanes and the parking lane (Third St.),
  2. bike lanes between the parking lane and the curb (Sycamore Lane), and
  3. bike paths adjacent to the street, between the curb and the sidewalk (Villanova Ave.).

The first bike lanes included all of these types, to test them in real life to see how effective they were. The on-road lanes worked best, the behind-parking lanes were the worst, and the adjacent paths were found to work in certain circumstances. This is an example of the wide level of experimentation that occurred during this period. Had the city tried to do extensive research without construction, it might have settled on an inferior design. And not having tried all three designs, it might not have recognized it as inferior, and the entire experiment could have been declared a failure.

Dale Lott (one of the early advocates for special bicycle facilities in Davis, who also conducted research as to their safety and effectiveness), “How Our Bike Lanes Were Born“, op-ed piece which appeared in the Davis Enterprise in 2003:

We insisted on some experiments that turned out well and some that were flops.

One flop was on the first block of Sycamore north of Fifth where we put bike lanes next to the curb with parking next to the auto travel lane. It looked great on paper, but was a mess on pavement. When cars turned into the University Mall driveway, they crossed the bike lane. Both driver and rider, whose view of each other had been obscured by the parked cars, had an emergency situation.

David Takemoto-Weerts (University of California, Davis Bicycle Coordinator, A Bicycle-Friendly Community, the Davis Model (conference presentation, 1998)

Because Davis pioneered the bike lane and other bicycle facilities in this country, it is not surprising that some “experiments” were less successful than others. One such example was the construction of “protected” bike lanes where motor vehicle and bicycle traffic was separated by a raised “buffer” or curbing. In some cases, the bike lane was established between the parking shoulder and the curb line (i.e. cars were parked on the left of the bike traffic lane). Needless to say, any “benefits” of such facilities were soon found to be outweighed by the many hazards created for their users.

Most such well-intentioned, but ill-fated designs were phased out long ago. However, some facility design decisions made decades ago were not so easy to remedy. The most pervasive example in Davis is the two-way bike path immediately adjacent to a roadway. Particularly problematic are single two-way paths located on only one side of the adjacent road. The problems associated with these designs have been described in any number of publications, and they are well illustrated at several locations in Davis. In spite of this documentation, some residents, city officials, and developers remain quite vocal in advocating such facilities when new construction is being planned and designed. The city and campus have attempted a variety of mitigation strategies to reduce the hazards or inefficiencies associated with these side paths, but many observers believe that continuing to build such facilities is wasteful at best.

Deleuw, Cather and Company.: Davis Bicycle Circulation and Safety Study. 1972 (excerpt — for complete document in three parts, see table of contents page.

Protected lanes

…Protected lanes located between the parking shoulder and curb line have most positive separation. However, the parked cars create sight distance problems at driveways and intersections. Inability to cross streets in midblock in this type of treatment results in two-way usege which, in turn, leads to intersection problems described subsequently…

Sidewalk and Independent paths

Sidewalk pathways eliminate midblock bike-motor vehicle friction. However, frictional interference of pedestrians may discourage usage of these facilities as does frequent interruption by cross streets and driveways or meandering of the path. An additional problem is establishment of a visual relationship between motor vehicles on the sidewalk path on approaches to intersections…

Davis, California historical documents

Thanks to John Ciccarelli, Robert Sommer and David Takemoto-Weerts — and David’s students — among others — I am able to post online a number of documents about bicycling in Davis, California and the Davis bicycle program. Davis has the longest experience with a bicycle program of any city in the USA, and a large population of cyclists thanks to its being the home of the University of California at Davis.

You may surf to my table of contents page for the Davis documents and a complete list of people I have to thank — but also please read the rest of this post:

Of particular note are the conclusions which Davis has reached about different types of bicycle facility designs. Davis pioneered some brilliant design innovations, for example, bicycle traffic circles. On that topic, also see video.

Davis also has been willing to learn from mistakes and move onward. In another post, I have assembled quotes about Davis’s experience with barrier-separated bike lanes, versus conventional bike lanes separated from the adjacent lane only by a painted stripe, an issue which is particularly relevant as I write this in 2010.

I approve of this?

UPDATE: This post gives background information on the intersection. I have now ridden through it, and my opinion of it has changed. I have another post about it, and a video. Please check them out.


The image below shows a special installation of traffic signals and markings at the intersection of 16th street, U Street and New Hampshire Avenue NW in Washington, DC. To enlarge the image so you can read the text descriptions, click on it. You also may have a look at a Google map satellite view. Then please return to this page for my comments.

16th Street, U Street and New Hampshire Avenue NW, Washington, DC

16th Street, U Street and New Hampshire Avenue NW, Washington, DC

Pierre L’Enfant and Andrew Ellicott — and let’s also not forget African-American surveyor Benjamin Banneker — laid out Washington’s streets from scratch —  in the pre-automotive 1790s. Washington’s diagonal avenues give it an openness and unique sense of place — but the resulting uneven-length blocks and multi-way intersections make for some serious headaches now. Some traffic movements are odd, traffic signals can not be synchronized efficiently…

Before the new installation, no signals in this intersection faced new Hampshire Avenue. Bicyclists would sometimes use New Hampshire Avenue for through travel, though its conflicting one-way segments made that illegal and there was no conflict-free crossing interval.

The illustration above is from a page posted by the government of the District of Columbia describing a new installation of contraflow bicycle lanes, bicycle waiting boxes and special traffic signals. At first glance, these may raise the hair on the back of the necks of people who are suspicious of special bicycle facilities treatments.

Look again. The bike boxes look odd only because they connect with diagonal New Hampshire Avenue. They are cross-street bike boxes — which bicyclists enter from the left. Bicyclists from New Hampshire Avenue enter on a separate signal phase from the motor traffic on 16th Street, rather than to creep up on the right side of motor vehicles, as with more-usual bike-box installations. Motorists do not have to crane their necks or stare into a right-side mirror looking for these bicyclists.

The cross-street bike boxes are even more conflict-free than usual. Because only bicycle traffic runs contraflow, bicyclists do not have to negotiate with any right-turning traffic when entering the intersection.

To summarize: this installation, importantly, does not violate the fundamental traffic-engineering principle of destination positioning at intersections, as so many special bicycle facilities installations do.

Or, looking at the same conclusion from a different point of view, the installation does not require or encourage bicyclists to do anything dangerous or stupid, and it offers reasonable travel efficiency considering the situation it addresses.

I am not going to say that this installation is perfect. I can see the following issues.

  • Bicyclists’ having to wait through two traffic-signal phases is inconvenient and might lead to scofflaw behavior. A “scramble phase” could allow crossing in one step and might even apply to bicyclists arriving from other directions. It would reduce the time allocated to for all the other phases, but it might be practical, and preferable, at times of low traffic. Signals and markings which only apply at some times could, however, be confusing.
  • The installation addresses only bicycle traffic entering the intersection from New Hampshire Avenue. Traffic control remains as it was for 16th street and U street. Considering the many ways in which bicycle travel could be made slower and/or more hazardous in the name of making it better, this may be a case of “best leave well enough alone,”  but on the other hand, real improvements might be possible.
  • The bike boxes on 16th street could be interpreted as encouraging bicyclists on that street to overtake motorists on the right, then swerve in front of them, as is the more conventional with bike boxes.
  • Just outside the lower left of the picture on New Hampshire Avenue, there is wrong-way parallel parking next to the bike lane. Motorists exiting wrong-way parking spaces are in head-on conflict with bicyclists, but cannot see them if another vehicle is parked ahead. (See illustrated description of wrong-way parallel parking elsewhere, if the explanation here is unclear.) At the top right, on the other hand, note that the bike lane is farther from the curb: this segment of New Hampshire Avenue has back-in right-angle parking, avoiding the sight-line problem.
  • And, while we’re at it, I have another issue with the street grid, though it’s common to many other cities and not readily subject to correction. Streets that go east and west guarantee that twice per year,  for several days, the Sun will rise and set directly along the streets, glaring into drivers’ eyes.  If the street grid ran northeast to southwest and northwest to southeast, this would never happen. All you Pierre L’Enfants of today designing new cities, please take notice, here’s your chance to acquire a reputation as Pierre L’Enfant Terrible!

This installation is the subject of experimentation sanctioned by the U.S. Federal Highway Administration, with observation, data recording and analysis to see how it works in practice. The experimentation may turn up more issues, or reveal that some are of little importance.

Now, dear readers, you also may also have points to add to the discussion. Let the comments fly.

See also: GreaterGreaterWashington blog entry about this installation; Washington, DC Department of Transportation page about it; Google maps satellite view.

Pennsylvania Avenue, Washington, DC: Incredible Shrinking Bike Lanes

A showcase example for  Federal promotion of special bicycle facilities in the USA has been laid down on Pennsylvania Avenue in Washington, DC, with bike lanes extending between the Capitol and the White House.  It’s quite a show, but it didn’t turn out exactly as planned.

Well, on with the show. On June 7, 2010 — as described in a press release and videos[Revised version as of 2016 without photo but with link to photo gallery] [Article announcing the event] [Version of article as of August, 2016] [Press release] League of American Bicyclists President Andy Clarke, Representative James Oberstar (D-MN), NBA basketball star Caron Butler and the Crown Prince of Denmark were out on Pennsylvania Avenue expressing their enthusiasm for the bike lanes, riding bicycles supplied by Specialized, a major American bicycle supplier. Why the Crown Prince? American bicycle facilities advocates hold Denmark up as an example. Why industry involvement? Because the industry sees special facilities for urban cycling as the key element in propelling the next wave of bicycle sales. Why politicians? Because public funding would have to pay for the facilities. Why Caron Butler? I don’t know! [Update: the blog post and press release indicate that Butler funded a bicycle giveaway program for children.]

Lone bicyclist on Pennsylvania Avenue bike lane in early morning; buses queued in background

Pennsylvania Avenue bike lanes, May 11, 2010

But, in its press release, the League of American Bicyclists borrowed a basketball expression, describing the Pennsylvania Avenue project as a “slam dunk.”

This wasn’t the first praise for the project. A month earlier, on May 12, the photo at the right appeared in a message sent to an e-mail list of the Alliance for Bicycling and Walking (a consortium of state and local advocacy groups) among other lists. The iconic bicyclist is riding off into the sunrise, toward the Capitol. In the background, tourist buses queue for their first run of the day. Accompanying text, by League of American Bicyclists board member Tim Young, reads:

I was just in Washington and rode the new Pennsylvania Ave Bike Lanes, so fun the paint was still drying. Awesome to ride from the White House on one end to Congress on the other, and have such huge dedicated space for bikes. You have to ride it!

Center lane was an unexpected design for me, but it works if you follow the signals and signs. Its casual riding, so much room and buffer, and the road is not that busy for its size, I understand about 30,000 ADT. You can see from this photo the massive bus use, so the curb lane is full of conflicts. The center rides fine. The only unhappy campers were taxi drivers wanting to make U turns mid block.

Photo: Mike Tongour, Bikes Belong lobbyist, rides towards Capital Hill.

(Bikes Belong is a bicycle industry lobbying organization which, among other efforts, lends substantial financial support to the League.)

Young may, however,  have spoken too soon about the ample width of the bike lanes. They had been installed over the weekend of May 1 and 2; promptly on Monday, May 3, the Mid-Atlantic division of the American Automobile Association issued a press release  suggesting that they would worsen traffic congestion. (That press release is no longer available on the AAA Web site, but I have made it available.) It has in turn been widely criticized by bicycling advocates, for example here and the criticism has been echoed in some media outlets, for example, here and here. The Washington Area Bicyclist Association, the local bicyclists’ advocacy group, asked its members to support the lanes, here.

Bicycling advocates pointed out that Pennsylvania Avenue was already relatively lightly traveled, as the blocks nearest the White House had been permanently closed to motor traffic following the 1995 bombing of the Federal Building in Oklahoma City. An AAA poll, cited in the press release, indicated that only 20% of members would feel compelled to become bicycle commuters if traffic congestion worsened. The bicycling advocates turned this finding on its head: 20% is a higher bicycling mode share than in any US city. Copenhagen’s bicycle mode share is hardly any larger, though its bicycle-to-work/school mode share is around 37%.

On May 20, the Washington Post reported that changes in the lanes were in the works. A quote:

Gabe Klein, director of the Department of Transportation, called to clarify that the delay in the opening of the bike lanes on Pennsylvania Avenue might not result in the lanes growing tighter.

Klein disclaimed bowing to any pressure and said the lanes needed to be “redesigned” to enhance the safety of bicyclists.

The article also described a Bike to Work Day rally to be held the next morning in support of the lanes and to be addressed by Rep. Earl Blumenauer (D-Portland, Oregon).

Two weeks later,  on June 7, Clarke, Oberstar, the Crown Prince and NBA basketball star Caron Butler were out in the bike lanes for their media event. Clarke returned to his office to describe the project as a “slam dunk.” In the light of the proposed changes, this event can be construed as support of the project in the face of a threat.

Slam dunk indeed. It turned out that bicyclists were slammed, and dunked.

On the next day, June 8, the Post published an article describing the planned modifications. Travel lanes that had been converted to bike lanes were to be restored, and the bike lanes moved to the median (growing tighter, in spite of what Mr. Klein had said). The article reports that the AAA applauded this change, while the Washington Area Bicyclist Association expressed concerns about conflicts between bicyclists and pedestrians.

The changes were made. On June 22, the lanes officially opened. On July 3,  independent journalist Matt Johnson rode the lanes and took photos. He wrote an article and posted his photos on Flickr. He gave anyone permission to use them, with attribution. I thank him.

The title of the article, “Pennsylvania Avenue Bike Lanes Still have a Few Flaws“, suggests that the lanes had been improved. The contents of the article and the photos show quite the opposite.  The space for bicyclists had been significantly reduced, and bicyclists were thrown into conflict with pedestrians at intersections.

Here’s a photo of the bike lanes, looking west across 9th Street NW, taken in mid-May. The layout is already rather strange, with turning bicyclists — including right-turning bicyclists — directed to merge left. The right-turning bicyclists have to  re-cross the stream of through-traveling bicyclists to get to the crosswalk which they are supposed to use.

Bike lanes at 9th St. NW, mid-May, 2010

Bike lanes at 9th St. NW, mid-May, 2010

Below is another photo which Johnson took at the same location on July 3. (You may click on either photo for a larger view.)

Bike lanes at 9th St. NW, July 3, 2010

Bike lanes at 9th St. NW, July 3, 2010

The space between the two lanes of opposite-direction bicycle traffic is gone — the available width is indeed tight if the lanes are to carry any substantial volume of bicycle traffic. But the intersections are weirdest of all. Through-traveling bicyclists now ride up and over the median refuge where pedestrians wait. The bike lanes are now immediately adjacent to the black, handlebar-snagging bollards that protect the traffic-signal poles. Turning bicyclists have it stranger yet: they are aimed straight at the traffic signal at the center of the median.

The one change that anyone could contend is a safety feature is the row of flex posts between each bike lane and the adjacent travel lane, intended to keep motorists from encroaching into the bike lane. Safety feature? Well, maybe. A flex post is harmless to a car, but it can easily take down a bicyclist.

A search of the League’s e-mail blasts and blog turned up blog posts responding to the AAA press release [version as of August, 2016, without photo] and reporting on the opening celebration [version as of August, 2016 without embedded photo but with link to photo gallery] for the reconfigured bike lanes on June 22, as well as the “slam dunk” post and a couple of others featuring the Crown Prince, but no mention of the redesign. Comments on the redesign turn up several times in a record of a live online chat with Washington Area bicyclist Association Executive director Shane Farthing. (Search on “Pennsylvania” inside the post to find them.)

Enough for now. This article is intended as a brief history. I’ve addressed technical issues only to the extent necessary to move the history along. I’ll be addressing them in detail in another post.

[Update: I have posted a video of a ride on these bike lanes, with narrative description. It addresses technical issues]

Save

Save

Save

Comments on a safety-in-numbers study

The University of California has published a study of pedestrian crashes in Oakland, California,

The Continuing Debate about Safety in Numbers—Data from Oakland, CA
Judy Geyer, Noah Raford and David Ragland, Traffic Safety Center;
Trinh Pham, Department of Statistics, UC Berkeley
UCB-ITS-TSC-2006-3

The full report is available online:

http://www.escholarship.org/uc/item/5498×882

John Forester, founder of the Effective Cycling program of cyclist education, and statistician, has demonstrated that the Safety in Numbers claim of Jacobsen (also cited in the Oakland paper) is faulty. Due to faulty math, a random set of numbers will generate the curve that apparently shows a decreasing crash rate with increasing numbers of users. This is not to say that the safety-in-numbers claim is false, but rather that Jacobsen has provided no evidence to support it. (Forester also questions Jacobsen’s explanation for safety in numbers as applied to bicyclists, but that’s a different issue.)

The Oakland report expresses the same complaint about Jacobsen’s math, and goes on to use better math to look for answers. Here’s a quote from page 5 (PDF numbering) of the Oakland report:

However, others are concerned that correlating collision rate (C/P) with pedestrian volume (P), (where C equals collisions and P equals pedestrian volume) will almost always yield a decreasing relationship due to the intrinsic relationship of the variable P and the fraction 1/P.

Tom Revay has generated a Microsoft Excel Workbook demonstrating how Jacobsen’s curve may be generated with  random data. Press the F9 key on a PC to refresh the random data. (Press Command [Apple] and = at the same time on a Mac. I thank Dan Carrigan for this information)

The Oakland study came up with some interesting and intriguing results. Here are a few; please correct me if I am wrong:

Pedestrians vs. Collisions/Pedestrian

Figure 4, p. 17, Pedestrians vs. Collisions/Pedestrian

  • The graph on p. 17, PDF numbering (click to see a larger version) shows the characteristic downward curve due to faulty math. However, the curve slopes back upwards for the intersections with the very highest numbers of pedestrians.
    p. 16, Pedestrians vs. Collisions

    Figure 3, p. 16, Pedestrians vs. Collisions

    A better graph (graph on p. 16, PDF numbering, click to see a larger version) shows crashes increasing with a steeper slope for the higher-volume intersections, worst at the intersections with the highest volume. Crash numbers are low enough, though, that the results for individual intersections are not statistically significant.

  • The Oakland study examines different intersections in the same community over the same time period rather than the same intersections at different times, or different communities with different volumes of pedestrian and vehicular traffic. The study can establish whether the safety in numbers effect applies only under the conditions it examined. Data from different times of day might possibly be checked against traffic volumes, though the results would be less robust and effects of lighting, alcohol use etc. would make them harder to interpret.
  • It is clear that a few intersections are outliers, with many more crashes than others. These intersections would be high on a priority list for improvements — though the actual numbers for individual intersections, again, are too low to be statistically significant.  The problem with lack of statistical significance highlights the importance of applying research data and operational analysis in determining where to make infrastructure improvements — crash data for an individual intersection are not statistically robust unless the intersection has an extremely bad problem. You apply research results and operational analysis so you can avoid collecting data on each intersection by killing and injuring people.
  • (See Results, p. 9, PDF numbering) Number of lanes on the primary and secondary streets, and number of marked and unmarked crosswalks, did not correlate with crash rates! (But note that this result is consistent with data on bicycling showing that riding on arterials is safer than on residential streets).
  • Despite the safety-in-numbers finding, the intersections with the largest numbers of crashes are still those with high pedestrian volumes. Increasing numbers decrease the rate of crashes, but not the number of crashes.
  • p. 18, Vehicles vs.Collisions/Pedestrian

    Figure 5, p. 18, Vehicles vs.Collisions/Pedestrian

    The crash rate increases for pedestrians as the number of vehicles increases (page 18, PDF numbering), though less rapidly than the number of vehicles. Is there a safety in numbers effect for vehicle operators as the number of vehicles increases? Yes, the likelihood that any particular driver will collide with a pedestrian decreases with the amount of vehicular traffic passing through an intersection — though the study doesn’t report this. The study doesn’t answer whether the result is achieved by improved signalization at high-volume intersections, or by depressing pedestrian volume (risk homeostasis), or by what other effect. The study also doesn’t say anything about crashes overall, as it doesn’t report on crashes not involving pedestrians.

All in all — interesting, intriguing, and careful research — but more research is needed!

Livable Streets proposal lacks credibility

I’m looking at a GOOD magazine/Streetsblog proposal for a “livable street”

This is a prime example of what I call the Photoshop school of traffic engineering. Anyone with computer graphics skills can generate a before-and-after comparison like this. Often, it looks very attractive to the untrained eye — but, whether the proposed changes make sense is another issue entirely.

It would be nice if the Streetsblog people who created this graphic had a few more clues about street design. Some of the issues:

Continue reading