Tag Archives: traffic calming

“Shared space” — longer video and discussion

This post is a companion to my earlier one titled “No Rules.” The video here shows my entire ride on Commercial Street in Provincetown, Massachusetts, with a forward and rearward view, while the one in “No Rules” shows only highlights in a forward view. I discuss the “shared space” phenomenon at length in this post.

Commercial Street is one lane wide and officially one-way, but it is heavily used by pedestrians and bicyclists traveling in both directions, to the extent that motorists can only travel at a very low speed and often must stop. Bicyclists also must take special care, ride slowly and often stop. Some do and others do not. Pedestrians need to be alert to the hazards. Some are and others are not.

“Shared space” has become a buzzword among people who want to “return the street to the people,” meaning, in reality, make the street into a pedestrian plaza — a social space. Pedestrians, then, serve as obstacles to slow down faster modes. “Shared space” advocates regard this as a benefit, and point to a reduction in the rate of serious crashes. This reduction, however, results from the very low speeds at which travel is possible in such an environment. Even so, there are safety problems. Even cycling at a moderate speed is hazardous to pedestrians — and equally, to cyclists who collide with pedestrians. As the video shows, I had to ride slowly and cautiously to avoid colliding with several pedestrians who made sudden, unpredictable moves.

Another buzzword is “no rules”. Sure, pedestrians can bump into each other without usually causing injury. “Shared-space” advocates, however, often consider cyclists to be like pedestrians — a serious misconception. Cyclists traveling at their normal speed can socialize only with each other, and are antisocial, not social, in a pedestrian plaza. Safe sharing of “Shared space” requires cyclists to travel so slowly that there is little advantage over walking. Cyclists and motorists in “shared space” must pay strict attention to the basic speed rule, to go no faster than is safe under the conditions at the time and place. Violate this, knock a pedestrian down, and then hope that you have good insurance. Other rules apply, as well, in many “shared space” installations: yielding before entering the roadway; overtaking on the left; exclusions or limited hours for motor traffic.

The one rule that most cyclists disregard on Commercial Street is established by one-way signs. Cyclists disregard it for a particular reason: there is no comparable street which allows travel in the opposite direction. Bradford Street, one block farther from the harbor, is hilly and carries regular motor traffic. Commercial Street is the location of businesses which appeal to tourists who pile off the ferries from Boston, while Bradford Street has few such businesses.

What would improve the situation here? The first thing I would suggest is to block off the west (up-Cape) end of Commercial street where it separates from Bradford Street so motor vehicles can’t enter, and to install signs directing them to use Bradford Street. I think that many of the motorists who enter Commercial street are tourists who don’t know what they are getting into. If they used Bradford Street instead, they would get where they are going sooner, and would need to travel at most one or two blocks on Commercial street to reach any destination. It might also be helpful to sanction contraflow bicycle travel, and paint a dashed line down the middle of Commercial street to encourage keeping to the right. Moving parking off Commercial street also could help, especially in the few blocks near the center of Provincetown where traffic is heaviest. That could at the very least allow more room for pedestrians without their getting into conflict with cyclists and motorists. There is an abandoned rail line — partly on a lightly-used dead-end street, and paralleling much of Bradford Street and Commercial Street. It could carry the bicycle traffic heading in and out of town.

Beyond that, I don’t see much that can be done. Commercial Street is what it is, a quaint, narrow street like those in many European cities. Short of a horrible disaster — a huge storm or tsunami which would destroy the entire waterfront — Commercial Street isn’t going to get any wider.

No rules?

Quite by chance, I encountered an advocate of “shared space” and had a conversation with him at the start of a ride I undertook to illustrate the concept. The advocate expressed that there are “no rules” in this kind of space, which is dominated by pedestrians. Do you agree?

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.

18 mph Speed Limit: European? Sensible? Read On.

In two consecutive issues of the estimable Southwest Cycling News (print) publication, I have seen the picture below.

18 mph Albuquerque sign

Editor Fred Meredith shot the photo of the sign on a bicycle boulevard — a low-traffic, residential street configured as a through route for bicyclists — in Albuquerque, New Mexico while attending the 2010 League of American Bicyclists National Rally. Meredith wears more than one bicycle helmet — he also works under contract for the League’s education program, so it is natural for him to attend the National Rally.

Now, please don’t get me wrong, I’m an instructor in the League’s program, and I’m also a proponent of bicycle boulevards and of low speed limits on residential streets. Many European residential streets have a similar speed limit. and so do some streets in Montréal, Québec, in Canada — as per the sign on the left in the photo below.

Some signs in Montréal, Québec

Some signs in Montréal, Québec

Similar speed limit, what? That sign reads 30!

Yes, it does: 30 kilometers per hour. Canada changed its speed limit signs from miles to kilometers in 1977, conforming to the rest of the world, the only major holdout nations being the USA and the United Kingdom. Part of Canada is French-speaking, the kilometer is a French invention, and that might have something to do with Canada’s divergence from its southern neighbor.

So, anyway, American bicycling advocates on pilgrimages to Europe see the 30 km/hour signs, which look like a good idea to them, and decide to transplant the idea back home.

As I said, I support lower speed limits. I have a few problems with the sign, though.

First of all, our bicycling advocates appear to be math-challenged — or perhaps they want to go a bit lower on speed limits than the Europeans.

30 km per hour converts to 18.64 miles per hour, rounded to the nearest 1/100th. Rounded to the nearest whole number, then, it’s 19 miles per hour — not 18.

There’s another problem with the number 18 — or for that matter, 19. Have you ever before seen a speed limit in miles per hour with a final digit other than zero or 5 — or in kilometers, with anything other than zero? No, you haven’t. There are a couple of reasons. The steps in speed limits need to be large enough to be meaningful. Also, a zero and a 5 look so different that they are very unlikely to be confused with each other at a glance, or if a sign is damaged or partially obscured. An 8, on the other hand, is easily confused with a 3, or a zero. A 9 is easily confused with a 2 or a 7.

The requirement that speed limits go by jumps of 5 or 10 is written into US standards documents. The US standard, the Manual on Uniform Traffic Control Devices, section 2B.13, includes the following wording:

The speed limits displayed shall be in multiples of 5 mph.

Am I nitpicking by raising these issues? I don’t think so. Confusion makes a speed limit harder to observe, and harder to enforce. So do speeds which must be estimated, between the markings on a speedometer. Failure to observe standards exposes governments to liability risks. A nonstandard speed limit can give speeders and their lawyers a legal loophole.

The issue is similar to the one with bike lane color that I described in an earlier post.

The usual school-zone speed limit in the USA is 20 mph. It is only slightly higher than the European and Canadian 30 km/hour speed limit, and it conforms to US standards. This same 20 mph speed limit is already being used in residential neighborhoods in the USA. If 20 mph is too high, 15 also is possible, and I have seen it, in parking lots and the loading/unloading areas of airport terminals.

Advocates of an 18 mph speed limit are acting in disregard of existing American standards which would give them very nearly the same speed limit, on a sign that is more readable and immune to legal challenges.

When and if the USA goes over to speed limits in kilometers per hour, the current speed limits will be adjusted up or down slightly so the numbers end in a zero, as in other countries.

If the USA makes the conversion, a large number of “speed limit 30″ signs will become available for re-use as 30 kilometers per hour, and the bicycling and neighborhood safety advocates can expect to have the genuine European speed limit at a bargain price. I will support them in that.

In defense of neighborhood traffic circles

Nieghborhood traffic circle in Berkeley, California

Neighborhood traffic circle in Berkeley, California

In a post to an e-mail list, I made the statement:

On narrow streets in residential areas…small traffic circles at intersections can slow traffic and reduce the temptation to use those streets for through travel…

…which elicited the following response from Ken O’Brien, whom I consider a friend, but who is also probably the most hard-core supporter of equal treatment for bicyclists and motorists I know. He rejects all special treatments, including ones which I regard as beneficial.

I’m very disappointed to read John Allen supports these foolish structures.

These bogus structures encourage left turning and straight-through traffic to enter intersections swinging right (to avoid and go around the obstacle). They encourage traffic to perform lateral merges (and a lateral merge away from the direction they intend to travel) immediately at the intersection. They break the rule that you want traffic to prepare for lateral merges early and separately from scanning for conditions ahead immediately at the intersection.

Please, please Mr Allen, reconsider your support for these illogical attempts at traffic calming.

I responded:

I can always count on Ken O’Brien to make principled and consistent comments based on traffic theory, and I would agree with most of his comments if such structures were installed on streets with fast or heavy traffic. In fact, one of my complaints about the reconstruction at the rotaries on Concord Avenue in Cambridge [Massachusetts] was the narrowing of the travel lanes, resulting in some of the very problems he describes.

I think that Ken and I can agree that rotaries do not inherently defy the rules of good, simple intersection design. A rotary [the Massachusetts name; also, "traffic circle" and in its modern, improved version, "roundabout"] is a street with several other streets entering at T intersections from the right, and the T intersection is a very ordinary type of intersection.

Drivers must merge with traffic in the rotary and then go around to the desired exit. When Ken says that drivers must make “a lateral merge _away_ from the direction they intend to travel” — well, they intend to travel around the rotary, and so they are merging into the traffic flow of the rotary. As drivers enter the rotary, conflicting traffic comes from only one direction, the left, rather than from three directions as in a “crossroads” intersection. Once in the rotary, it comes from only one direction, the right. To this extent, I do not agree with Ken’s comments about traffic flow. True, traveling straight through or turning left is more complicated and slower in a rotary than at a “crossroads” intersection — if there is no conflicting traffic — but that fact does not imply any inherent disagreement with ordinary traffic rules.

Bicyclists are impeded by the small rotaries much less than motorists are. The only maneuver that is slower for a bicyclist is the left turn: a bicyclist must go around the rotary to make a left turn. Because of the narrowness of a bicycle compared with motor vehicles (other than motorcycles), the small rotary does not slow a bicyclist’s travel at all for through travel or right turns.

Ken says that the small rotaries that “break the rule that you want traffic to prepare for lateral merges early and separately from scanning for conditions ahead immediately at the intersection.”

Actually, as these rotaries are typically on two-lane, two-way or one-lane, one-way streets, they don’t require any merges at all before the intersection, except by operators of slow, narrow vehicles such as bicycles. A bicyclist should merge into the traffic flow before going around the rotary, but then a bicyclist should do this for through travel at any rotary [and at many if not most other intersections]. The merge is particularly easy at the small rotaries because motorists, with their need to steer right around the center island, must slow to bicycle speed before entering the rotary. I’ve been in Berkeley [California] repeatedly and ridden through such rotaries, and I did not get the uneasy feeling I always get with bikeway junctions which defy the rules of traffic flow, the feeling that drivers, including me, need to have eyes in the back of our heads or X-ray vision to see traffic that might conflict with the movements we are preparing.

Now let’s step back a bit and look at the larger issue of reduction of traffic speed and volume in residential neighborhoods.

Wherever residential streets provide useful shortcuts or alternative routes, and especially in cities like Berkeley with a grid traffic pattern, use of residential streets by through motor traffic becomes a nuisance and a hazard. Residents demand a solution. What solutions are available?

Attempting to ban non-resident motorists would be unworkable, and a violation of the basic right of free travel. Location-specific electronic monitoring and control of vehicle speeds is an idea whose time has not yet come. Low speed limits and traffic-law enforcement can work if they have enough political support, but budgets for law enforcement are often inadequate, and while residents want to prevent speeding in their own neighborhoods, they want to avoid speeding tickets in other neighborhoods. Everyone has only one own neighborhood but there are many other neighborhoods, and so the political force to weaken enforcement usually wins out. We’ve seen this happen recently with challenges to photo-monitoring and ticketing of speeding motorists.

Because the “soft” measures aren’t very effective, residents demand, and you will find, some form of traffic calming in almost any residential neighborhood. Then the question becomes: what form of traffic calming?

The “spaghetti” pattern of curved streets in many newer suburban developments? Well, that can’t be retrofitted onto existing neighborhoods, and it’s confusing too — getting lost on the curved streets is very easy. Cul de sac development patterns? They force everyone including bicyclists to take long, roundabout routes on major arterials. Conflicting one-way signs from one block to the next (a favorite approach in the Boston, Massachusetts area)? That’s good at reducing the traffic volume on the residential streets, but works sorely to the disadvantage of bicyclists.

Bicycle-permeable barriers and diverters to break up through routes? Berkeley has some of these and I think they have their place, but they also can pose hazards if they result in nonstandard traffic movements, and they pose an issue of quick access for emergency vehicles. Speed humps and speed tables? I think they also have their place, but they do pose the issue of possible damage to vehicles. Bulb-outs, narrowing of the travel way, chicanes (making the traveled part of the street weave from one side to the other, for example by alternating parking on one side and then the other)? I think these measures have their place too, but they can work sorely to the disadvantage of bicyclists if the travel way is excessively narrowed. Snow clearance also becomes more difficult as the street gets more complicated.

All in all, I think that for bicyclists, the small rotaries are one of the least disadvantageous and most advantageous forms of traffic calming. By preventing motorists from traveling through intersections at high speed, the small rotaries succeed in reducing the speed and volume of traffic on the residential streets very substantially. Through-traveling motorists are discouraged from using these streets and are more likely to use arterial streets instead.

I’m sure that the success of the rotaries depends on design details; in particular, the traffic island must be large enough to accommodate the turning radii of vehicles that use the intersection. Success also depends on location. I have indeed seen one such rotary that failed — installed on Concord Street in Wellesley Lower Falls, Massachusetts and was made of collapsible, reflectorized poles. I wish I had a photo of it, but vehicles damaged it and it had been removed within a few weeks, before I got back to it with a camera.

Concord Street, which becomes Park Street in Weston, is a minor arterial street with a connection at each end to a numbered state highway and another connection in the middle to the Massachusetts Turnpike. As much as residents living along this street might have wanted otherwise, the needs and desires of through-traveling motorists prevailed. The small rotaries in Berkeley, on the other hand, do appear to have succeeded.