Tag Archives: curb

Barrier features

The same barrier can have more than one of the characteristics listed below, and they may be different for different types of vehicles.

  • Containment: The barrier prevents a vehicle from, for example, going over a cliff, or straying into oncoming traffic. Examples: curbs, guardrails, Jersey barriers.
  • Deflection: The barrier guides a vehicle that has gone off course back into the intended direction of travel. Examples: Jersey barriers, guardrails.
  • Threat: The barrier is hazardous in itself, so drivers shy away from it. Example: boulders, rigid bollards.
  • Sham: The barrier appears to pose a threat of damage to a vehicle but in fact is designed to minimize or avoid damage. Example: flex posts.
  • Stop: The barrier is intended to stop a vehicle approaching it.
  • Energy-absorbing: The barrier is designed to lengthen the time and so decrease the severity of an impact — same idea as with air bags or helmets. Examples. crash cushions, deformable barrier walls.
  • Warning: The barrier generates an audible or visual warning. Examples: rumble strips, proximity alarms.
  • Virtual: The barrier is established using signs, signals or markings and the laws which pertain to them.

A barrier may be benign for dual-track motor vehicles, yet  overturn single-track vehicles. These can topple over a low guardrail or Jersey barrier. A sham barrier for dual-track vehicles such as a flex post can tangle with the pedal or leg of a bicyclist, becoming a threat barrier. Reflectorized pavement markers, which are little more than a virtual barrier for dual-track vehicles, can throw a bicyclist –see this video example.

These considerations are lost in the design of many bicycle facilities. Barriers that are hazardous to bicyclists are being used because they are normal traffic-engineering practice, sometimes only due to lack of knowledge but sometimes enforced through design standards.

On the other hand, a high railing with a handlebar rub strip can serve as an effective and safe deflection barrier for bicyclists, even though it may be too weak to contain a heavier dual-track vehicle.

In Orlando, Florida recently, I saw two other examples of misuse of barriers:

  • Flex posts used ahead of and behind a parallel parking space which had been reconfigured as a bicycle parking station. Motorists parking in the next spaces would expect a light, stopping impact if they moved too far forward or back at very low speed. The colloquial expression is “kissing bumpers.”  Lacking this warning, a motorist already had backed up into the flex posts and damaged one of the bike racks. Here, rigid bollards or a guardrail would be appropriate.
  • Raised reflectorized pavement markers are being used on bike lane lines, neglecting the fact that bicyclists must enter and leave the bike lane, and often do best to ride along its edge. Nationally recognized guidelines specifically prohibit the use of raised markers here, for that reason.

The most common misused barrier for bicyclists is probably the low railing, which will topple a bicycle over. That is seen in many different varieties, ranging from the conventional Jersey barrier or guardrail to low wooden curbs lining boardwalks, to hand-height railings alongside paths.

Manufacturing traffic jams on Grand Street, Manhattan

Someone has watched my video of Grand Street, in Manhattan, and commented:

John, I watched the Grand Street video (which was kind of fun) but I couldn’t help but notice you are passing a lot of cars, which makes your average speed seem reasonable for the environment.

That average speed, including waits for traffic lights, was 5.5 miles per hour, half my usual. Yes, I do wait for the lights, though many New York bicyclists aren’t so patient.

Please have a look at the video so you can evaluate the rest of this post. Note especially the bus stopped in the street near the start of the video, because that will play in my comments.

Why were my riding companion John Schubert and I passing a lot of cars — and not only parked cars? The others were stopped cars. Even at 5.5 mph, you can pass stopped cars.

Grand Street is one block north of a major arterial, Canal Street, and carries overflow traffic arriving from New Jersey via the Holland Tunnel. In case you want more detail, I’ve posted photo gallery with maps online. I thank John Ciccarelli, John Schubert and Steve Faust, my companions in exploring Grand Street, for the commentary and photos which they contributed.

Here’s one photo, as an example — and you may click on it to see it in the photo gallery. That’s Steve Faust, in the yellow parka.

Trucks blocking the Grand Street bikeway

Trucks blocking the Grand Street bikeway

Grand Street passes through Manhattan’s Chinatown — accounting for the street vendors standing and walking in the bikeway near the end of the video. Grand Street also is where the infamous Chinatown intercity buses pick up and discharge passengers, to avoid paying to use the Port Authority terminal uptown.

Grand Street now has only one travel lane. A second lane was removed to create the bikeway. Whenever a bus stops — or any other vehicle stops in the travel lane — all other traffic stops and waits behind it. Traffic backs up for several blocks.

The bus drivers park the buses diagonally to prevent motorists from sneaking past and colliding with bus passengers, though this does not prevent bicyclists from sneaking past and colliding with bus passengers. You can see one of the buses parked diagonally near the start of my video.

The traffic backups, then, illustrate the law of unintended consequences. The backups result from the redesign that created the bikeway. Possibly, the designers thought that they would calm traffic by reducing Grand Street from two travel lanes to one, in the hope that the traffic from New Jersey would go elsewhere. It didn’t work. To calm traffic, you have to reduce the actual traffic, rather than to try to cram the same traffic onto a street which can’t accommodate it. Instead of calming traffic, the designers created traffic jams, increasing fuel consumption and air pollution.

My observation about traffic flow before the redesign is confirmed by an early, prototypical pre-Streetfilms video. The video stars Mark Gorton, the money man behind Streetfilms, and shows conditions on Grand Street before the redesign. Motor traffic flowed smoothly. Gorton shows vehicles stopped to load and unload, but they don’t block the street, with a second lane available for overtaking.

Gorton’s main concern is with width of the sidewalks, a valid concern in my opinion, though the sidewalks are in fact only narrow in some blocks, and Gorton takes his advocacy to the opposite extreme. He shows a Photoshopped example of how we need to “return control of the street to the communities that live here and the people that live here” by converting part of the roadway into an open-air restaurant — placing restaurant patrons elbow-to-rear-view mirror with moving motor vehicles, where the diners can enjoy a fine mix of food aromas and exhaust stench. This treatment reflects the influence of the “shared space” designs of British architect Benjamin Hamilton-Baillie. These treatments turn the entire street into pedestrian space, and tame motorists, because they can now safely travel only at pedestrian speed without killing pedestrians.

Tellingly, Mr. Gorton never mentions bicycling. Evidently, he had not yet discovered it.

“Return to the people” is code language for “take away space from motorized uses.” That is, to take control away from people who use motor vehicles and give it to “the people,” who all agree perfectly with the point of view expressed in the video. If that sounds vaguely Leninist to you, well, yes, I think so too. Ah, New York, where a wealthy hedge fund manager sounds off with Leninist rhetoric!

Real-world, American-style political pressures came to bear, and we now see the outcome. It’s rather clear that the community, some community — some people — residents, or business people, probably both, and for better or worse — wanted parking for motor vehicles, because there’s still nearly as much as before. On the other hand, Grand Street now has restricted loading zones — and not enough to meet demand. The business community either didn’t understand what would happen, or had too little political clout to demand more space.

Part of the street’s width was, however, “returned to the people” as a bikeway which is, in reality, a sidewalk extension, an outcome so predictable that I would have to laugh if the street hadn’t become such a traffic tangle, and if I weren’t required by law to ride on that sidewalk extension.

Bicyclists didn’t come out very well in this political exercise, and neither did motorists. Pedestrians came out best. They got their wider sidewalk, even if it is supposed to be a bikeway.

OK, now I’ve complained, so it’s my duty to offer a positive alternative.

Are you expecting a screed now on the joys of bicycling in Manhattan traffic on streets without any special treatment for bicyclists? Sorry to disappoint you, I’m not going to claim that Grand Street was a great street to ride on before the bikeway was constructed.

In my opinion, the Grand Street design is not thoroughgoing enough — not radical enough in one sense and not conservative enough in another. To make the street safe and attractive to bicyclists, including younger and less skillful ones, it would be necessary to displace through motor traffic to another street, and to get bicyclists out of the pedestrian zone. A way to accomplish that would be to traffic-calm Grand Street (or maybe another nearby parallel street) using barriers and diverters, more or less like the ones in Berkeley, California — so the street carries only light, local traffic.

In other words, transform the street into a neighborhood street, whose main purpose is local transportation at neighborhood-friendly speeds, like the bicycle boulevards in Berkeley — not a segregated mess, and not a pedestrian playground like upper Broadway in Manhattan. Many crosstown streets in Manhattan look promising for the treatment I propose, and are quite easy to ride now, even without intentional traffic calming.

If the volume of motor traffic were much lower, we might also consider widening the sidewalks where needed.

You may notice my heresy, from the point of view of segregationist bicycling advocates: some motor traffic must remain, as on the Berkeley streets, so the entire street doesn’t become a shared-space ped zone where pedestrians walk with abandon, and bicyclists have to play dodg’em.

John Schubert and I shot another video on Grand Street the same day. At the end of the video, you may view how motorists harassed us on a section without the bikeway, but while on the part with the bikeway, we waited over a minute for a Chinatown bus to unload, had to ride very slowly at one point behind a man with a food vending cart, and had to ride in the travel lane for several blocks where the bikeway was obstructed.

You might also have a look at this video by a unicyclist. It’s a bit shaky, but he comes to the same conclusions I do.

The Gilham Road raised bike lane, Eugene, Oregon

As a reader has commented on the Gilham Road, Eugene, Oregon raised bicycle lane in response to an earlier post, I’ve decided to follow up with some additional information about it.

Here’s a photo of the lane during installation.

Raised lane on Gilham Road, Eugene, Oregon

Raised lane on Gilham Road, Eugene, Oregon

I thank former Eugene Bicycle Coordinator Diane Bishop for sending me the photo. Her comments in the e-mail which accompanied the photo in February, 2002 are as follows:

I’m curious if you have seen or used any raised bicycle lanes? We installed one this summer and have had mixed reviews from users. Mostly the motorists don’t like it because they are forced to slow down (the road curves around various median islands, etc, and the travel lanes are 10′ wide, dropping the comfortable speed to about 20-25mph). But I”ve also gotten mixed reviews from cyclists. Most really like it, but some are concerned about the slope between the bike lane and the car lane. I’ve attached a photo so you can see what we did. This was taken during construction so we hadn’t done the landscaping, finished the sidewalk, or done the lane line painting. The bike lane stripe is at the bottom of the sloped surface now. The bike lanes are concrete, the auto lanes are asphalt.

The photo was taken at the intersection in the Google map below, looking south.


View Larger Map

Microsoft’s Bing mapping application offers a more detailed view, but you will have to open Bing separately to move around or zoom the view.

Microsoft Bing view of Gilham Road at Ayers Road, Eugene, Oregon

Microsoft Bing view of Gilham Road at Ayers Road, Eugene, Oregon

I responded to Ms. Bishop, as follows:

You asked me for my opinion, so here it is.

As much as political participation is important in our democratic process, I wouldn’t trust either bicyclists’ or motorists’ opinions of the facility. These opinions generally are swayed by perceived self-interest and don’t reflect professional training. Let’s consider the actual operational characteristics and crash rate.

I’m no fan of raised lanes (called “cycle tracks” in Europe). This design is common in early facilities installed in Europe, but now there is a heavy backlash against them, because studies have revealed them to have a much higher crash rate than riding in the street. The German ADFC has strongly opposed them for the past several years, since the study results came out. The ADFC recommends street-level bike lanes instead. [This press release] is typical of the ADFC position.

“Originally, cycle tracks were constructed to protect bicyclists from motor traffic. But since then, the number of studies which show that the risk of accidents is markedly higher on cycle tracks than on the streets has been growing. Bicyclists who are traveling on a two-way cycle track in an urban area on the left side of the street have 11.9 times the accident risk they would have on the streets. The cause of this danger is an incorrect political promotion of bicycling over the past few decades. In the past, travelers were segregated. Consequently, bicyclists and motorists could not see one another. At junctions, the bicycle traffic is directed onto the street, unexpected by the motorists. And so we have the typical urban bicycle accident. A bicyclist traveling straight ahead, struck by a turning motorist, is the most common type of bicycle accident involving a motor vehicle, states Stefan Brandtner, press contact for the All-German Bicycle Club (ADFC) Baden-Württemberg section.”

A survey of research on the accident rates of streets, bicycle paths and sidewalks is available on the Internet. And here are some links to specific studies posted on the Internet. Some (particularly Pasanen and Wachtel-Lewiston) are well-controlled for the same bicyclist population on the different types of facilities, while others are not, and so the difference in accident rates probably reflects to some degree that people who choose to ride on sidewalks generally are less skilled.

The Risks of Cycling by Dr. Eero Pasanen, Helsinki, Finland, higher car-bike collision rate for one-way sidepaths compared with streets, even though pedestrians are prohibited from the sidepaths (very similar to the installation shown). Extremely high rate of car-bike collisions with bicyclists crossing intersection on left sidepath.

Adult Bicyclists in the U.S. by Dr. William Moritz. Relative danger index 16 times as high for sidewalk riding as for major street without bicycle facilities. (Data include all crashes, not just car-bike collisions).

A Survey of North American Bicycle Commuters, by Dr. William Moritz. Relative danger index 5.32 times as high on “other” facilities (mostly sidewalks) as on average of all facilities (mostly streets). Data include all crashes, not just car-bike collisions. Lower ratio than in previous study probably related to typically lower speed and overall higher crash rate of average commuters compared with avid adult cyclists.

Alan Wachtel and Diana Lewiston, Risk Factors for Bicycle-Motor Vehicle Collisions at Intersections (ITE Journal, September 1994). Car-bike collision rate 1.8 times as high for sidewalk riding as for streets.

[The following documents] reach similar conclusions:

Sidewalk Bicycle Safety Issues, by Lisa Aultman-Hall and Michael F. Adams Jr. Bicycle accident rate 6 to 10 times as high as sidewalks as on streets in Toronto. (PDF document. See page 4.)

Toronto Bicycle Commuter Safety Rates, by Lisa Aultman-Hall and M. Georgina Kaltenecker. 4 times as high injury accident rate on sidewalks as on streets (PDF document. See table 5, page 19).

On the facility shown, the bicyclist is confined to the space between the slope down to street level, and the pedal-catching curb on the other side. I don’t know exactly how wide the lane is in the installation shown, but it appears to be no wider than 5 feet, with no shoulders, and with shy distance from the curb at one side and the downslope at the other side, the lane’s effective width is much narrower. The AASHTO minimum for a one-way bicycle path is 6 feet, *with* 2 feet of clearance at either side.

So this facility is not wide enough for one bicyclist to overtake another comfortably, even less so for a bicycle to overtake an adult trike or cargo bike of the type Jan Vandertuin is making (last I knew) in Eugene. Even aside from these examples, the carrying capacity of this lane is seriously reduced by its being raised. When bicyclists ride at street level (with or without a bike lane) they may merge outside the bike lane as necessary if the bike lane becomes crowded. In this installation, they can drop down to the street only at the cost of an uncomfortable and somewhat hazardous descent and ascent over the sloped edge. In wet, or worse, icy weather, or if sand or trash has accumulated at the bottom of the sloped edge, a bicyclist could easily be toppled by it.

The raised lane on each side also is bound to be used for two-way travel, because bicyclists do not perceive it as part of the street, and because it is much less convenient to get to the raised lane on the opposite side than it would be to get to a street-level lane on the opposite side. Left-side travel, as the studies show, greatly increases the risk of car-bike collisions. Some bicyclists would choose to ride on a sidewalk anyway — consider a child who wanted to get from one house to another on the left side of the street in the photo — but I don’t like constructing a facility specifically for bicyclists which encourages this behavior (as opposed to a bike route or street-level bike lane, which encourages right-way travel).

Naive bicyclists may assume that they are being “protected” from overtaking traffic by a raised lane, but the lane will cause more crashes than it prevents — certainly so in the case of single-bike and bike-bike crashes and almost certainly so in the case of car-bike crashes, by constraining the bicyclists’ line of travel and leading to a false sense of security. There appears to be an intersection in the background where the raised lane does not go down to street level before and after the intersection to allow merges (is this correct?). The motorists, than, are constrained to make their right turns from the left lane and the bicyclists, except for those at the ends of the skills spectrum — who are well-trained in vehicular techniques or who, on the other hand, make left turns as pedestrians — are likely to turn left from the right lane.

Often the motivation for a particular bicycle facility design is to affect the behavior of *motorists* rather than bicyclists. The classic reason for this has been to make things easier for motorists by getting bicyclists off the road. But here the goal appears to be to make things *harder* for motorists and slow them down by narrowing the lane width they can use. There are many other traffic calming and enforcement measures to slow traffic down and reduce its volume without constructing a problematic bicycle facility.

Another motive for constructing bicycle facilities is often to encourage people to ride bicycles, but again, there are many alternatives in design, and an unsafe facility which is popular is the kind most likely to lead to crashes!

I DO like gently sloped curbs at the RIGHT edge of the area in which bicyclists ride. With such a curb (commonly used on Cape Cod and called the “Cape Cod berm” here in Massachusetts), the trash, sand, water and ice problems still occur but at least most of the time a bicyclist who has strayed off the road can go safely up over the curb.

It appears that there is also a drainage issue. With no storm grate in the bike lane, and a curb at the right side, the lane will only drain if it slopes toward the street. It may be properly sloped now, but concrete slabs tend to tilt after a few years.

Essentially, I don’t see any significant difference between this facility and a sidewalk as far as bicyclists are concerned, other than that pedestrians have a separate sidewalk. I favor traffic calming measures in residential areas, with bicyclists traveling on the street, wide outside lanes and sometimes bike lanes at street level (though bike lanes are often installed where they create turning and crossing conflicts, and other solutions would be preferable); also bicycle paths away from roads to fill in the “missing links” in a bicycle route network, as discussed in the Oregon bicycle plan. This is my honest opinion and I hope it doesn’t upset you too much!

And in turn, Ms. Bishop replied:

On your raised bicycle lane response: no, you didn’t upset me. I’m not sure I agree with some of your comments, but I’m here and can see the lane and use it and you haven’t had that chance. Now that we have had it installed for a while and I’ve had a chance to ride it on several occasions, I’ve begun thinking we probably won’t keep this in our “toolbox” of street treatments. However, there are some things that seem to be good. I haven’t done a video study of the lane usage yet because it was completed so late in the fall last year. I’ll be doing that this spring. If I come up with
anything useful, I’ll let you know.

We don’t get snow or ice here (well, MAYBE a sprinkling of snow that lasts about 1/2 hr. once a year) but we do get a lot of rain. I was concerned about the sloped surface being slippery, but I’ve found it surprisingly easy to ride in the rain. I’ve also tested running up and down the slope pulling various trailers and they track as smoothly I can’t tell the difference from riding on a flat surface, even when one trailer wheel is over the edge while I’m still on the flat bike lane surface. One of the concerns raised by the neighbors (that I haven’t seen materialize) was that the kids would be out there using the sloped surface for playing with their bikes and skateboards.

I think you may be right about less competent cyclists not thinking about merging down into the auto lane to make their left turn. I hadn’t anticipated that when we decided to build the lanes. But I don’t think it will lead to more 2-way riding for 2 reasons: we have sidewalks for those you mentioned who would only be traveling a few houses away and those sidewalks are more accessible; and also because the traffic is relatively light on the street where we have the raised bike lanes (its a neighborhood collector).

For your suggestions on why we might have tried the design, actually you were right about the traffic calming interest…some of our folks were looking for ways to reinforce other traffic calming methods they built into the project. However, *I* was more interested in trying out a bike facility that might appeal more to children in order to get them off the sidewalks (which I agree with you are much more dangerous than the street). Our hope was that we could get them out in the street area where they will be seen by the motorists and slightly separated so they would be willing to try it. Raising them slightly higher seems to have the added benefit that motorists can see them better. I”m not sure we really accomplished all that.

So, thanks for your ideas. Like I said, I don’t think we are going to do that design again, but it was an interesting experiment. We want to make this community even more bicycle-friendly than it is, so are willing to try different approaches. Unfortunately I had very little time to research the design and, while [State of Oregon Bicycle coordinator] Michael Ronkin had it in the state bike/ped plan, he couldn’t suggest people or communities to check with in Europe.

And in turn, I replied:

Thank you very much for your reply. From your description, the sloped surface between the bike lane and the roadway appears to be less severe than it appears in the photo.

On another topic: there is a very interesting citation of a rather old Eugene study in a paper by John Williams, Alex Sorton and Tom Walsh. Dr. Sorton has told me that the paper includes data on the crash risks on streets, sidewalks and off-road paths. I would be most interested in knowing more about the study and if possible, obtaining a copy of it. I would be willing to pay for copying expenses and offer a service in return: conversion of the study into computer-readable format as I have done with a several other studies including, most recently, the classic 1976 Bikecentennial study — which I have posted it on my site.

This inquiry led to Ms. Bishop’s sending me a copy of the 1979 Eugene bicycle plan report, which I scanned and posted on the Internet — but that’s another story.

Mountable curbs

Mountable curbs have been suggested as a way to separate bike lanes or so-called “cycle tracks” from the rest of the street.

I am not in favor of such curbs. After all, any obstacle has hazard potential, and a mountable curb can have more than you would imagine.

As a cyclist rides along a mountable curb, tire “drift”, the slope and the offset front-tire contact patch make the bicycle hard to steer, so it must be held in a straight line by a continual effort. A similar issue with a different cause is discussed here.

Worse, if a mountable curb is slippery, it is no longer mountable, though it may deceptively still appear to be. The resulting fall may be a skidding-type fall or a diversion-type fall, in which the bicycle’s front wheel is swept to the side.

Trash, sand, snow or ice can accumulate along the curb. Installation of a curb-separated “cycle track” on a conventionally crowned roadway would require sloping the road surface away from the new curb to avoid this problem.

Even this unusual measure would not make snowplowing or street cleaning any easier, with an abrupt longitudinal change in elevation in the traveled way.

An approach used in Copenhagen is described here — a second line of drains at the curb (in the case shown, not mountable). The drains carry away standing water but does not solve the problems with trash, sand, refreezing water in the added, new gutter, snow clearance or street cleaning.

Cambridge, Massachusetts bicycle coordinator Cara Seiderman has shown a photo of a machine with a large, cylindrical, horizontal rotating brush used to clear snow from Copenhagen facilities. Perhaps this answers some of the issues with snow clearance and perhaps it also is used for street cleaning, but the expense is considerable, and the need for such equipment may not even be considered when a facility is constructed.

Snow clearance and ice melt issues on the 9th Avenue facility in New York City are described here; this is a barrier-separated rather than curb-separated facility, but the issues are similar. The bikeway here is wide enough that conventional snowplows could be used, but refreezing of meltwater from the windrow of snow between the bikeway and the street required heavy salting, and salt rusts bicycles.

So, is the prohibition of a barrier between a bike lane and the rest of the street in the AASHTO bike guide arbitrary? Does it only reflect issues with cyclists’ being able to enter and leave a bike lane, which can be addressed with a mountable curb? Not hardly.

Promotion of curb-separated bikeways, without considering the technical issues,or with “band” aid solutions such as mountable curbs, is all too typical of much bicycling advocacy.

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…

Ciccarelli on cycle tracks

John Ciccarelli is a consultant on bicycling and a League of American Bicyclists-certified cycling instructor who specializes in teaching adults who have never ridden a bicycle before. His comments here are reprinted by permission, and are in response to an e-mail he cites.

Subject: Re: Making Cycling Irresistible: Lessons from the Netherlands, Denmark, and Germany
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Safe separation with the Copenhagen curb?

How does a Copenhagen cycle track make bicycling safer? By putting bicyclists behind a low curb, a curb which a motor vehicle with its big tires can mount, but a bicycle can’t. The curb increases safety for bicyclists the way a streetcar track does.

Copenhagen curbed cycle track

A cyclist rides on a Copenhagen cycle track. Google Street View photo.

Oh, but wait — a streetcar track is a hazard to bicyclists, isn’t it?

So, let’s try to figure out the logic behind the Copenhagen curb. I think that it goes something like this:

“Bicyclists are sort of halfway between pedestrians and motorists, so we’ll put them behind a little curb about half as high as the sidewalk.”

This is reasoning by analogy. Reasoning by analogy is perilous if the analogy doesn’t hold. This one certainly doesn’t, so let’s look a little bit deeper.
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Hawthorne Bridge discussion gets thorny

Riding a bicycle on a sidewalk is rarely a better choice than riding in the street, but it is better on the Hawthorne bridge in Portland, Oregon, which has a narrow roadway with a treacherous steel-grid deck.

I first rode across this bridge in 1987. As of my more recent exploration of the bridge in September, 2008, the sidewalks have been widened significantly, and the routes to and from them greatly improved.

My friend Kat Iverson rode behind me with her helmet camera and shot the 5-minute video which you may view here.

More recently yet, I have read a blog posting by Mark Stosberg about the bridge. He and I agree that riding on the sidewalk is a necessary evil in this situation. He even links to my Web site as a reference. He states correctly that there are “no roads or driveways to cross on the bridge while traveling westbound.”

But just about there, my agreement with him begins to fade.

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