Tag Archives: crosswalk

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.

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

The full report is available online:


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:

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Guest posting: John Ciccarelli on the NYC Broadway bikeway

[John Ciccarelli is a consultant on bicycling, League of American Bicyclists Cycling Instructor and member of the Bicycle Technical Committee of the National Committee on Uniform Traffic Control Devices. These comments are based on his observations during a field trip to examine bicycle facilities in New York City in December of 2008.]

Broadway bikeway, Manhattan

Broadway bikeway: clogged with pedestrians

For me, the pedestrian conflicts on a new unconventional Manhattan bikeway — on the pedestrian-enhanced blocks of Broadway starting south from Times Square — rendered that bikeway nearly useless — even though those blocks of Broadway are similar to the
9th Avenue layout in several ways:

  • Both streets are multi-lane one-way-southbound
  • Both have a left-curbside one-way bikeway
  • At intersections there is a bike signal and a left-turn pocket and turn-arrow for motor vehicles (where the cross street is two-way or one-way-left) Continue reading

Comparing crosswalk and bike box

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