Facts and research about bicycle "sidepaths", trails, and on-road bicycle facilities

The following are facts and research related to the issue of "Sidepaths"--trails or "wide sidewalks" intended for bicyclist use that are built parallel to and immediately adjacent to roads or highways.

The information below was collected in reference to a current study for widening 150 Hwy from Grandview to Lee's Summit. However, the issues and research apply to many projects, especially MoDOT projects, around the state of Missouri.

One reason the bicycling community is so interested in this issue is that all the research and studies in this area back up completely the experienced bicyclist's experience on the road and on the trail.

Bicycle facilities on the road can be designed well and can work well.

A trail that is completely separated from traffic can also work well (think of the Katy Trail or the Indian Creek Trail).

But a bicycle "trail", "sidepath" that goes alongside a roadway is simply a facility that does not work. It is not safe. The only ways it can be made safe is by completely eliminating all the intersections of the trail and the roadway, including cross-streets and driveways or by taking rather dramatic measures at each and every driveway and intersection crossing--measures we have never seen implemented in Missouri. 

There are about three exceptions to the "no bicycle sidepaths" rule, and only three:

1. If the sidepath is a short segment, certainly less than a mile long and preferably less than 1/2 to 1/4 mile long, that has very few driveways or intersections crossing it, and (most importantly) connects two other good, high-quality trail sections that otherwise could not be connected.
2. If the sidepath is actually completely separated from traffic, (especially) including cross-traffic. Most commonly this works in conjunction with freeways or other limited-access highways. For instance, the trail proposed for the K-10 corridor will use underpasses or overpasses at *every* road crossing. Thus users will be able to travel for about 20 miles without interacting with motor traffic at all.
3. When dramatic and effective measures are taken at each and every driveway and intersection crossing that intersects the sidepath. This is how sidepath type facilities and separated bike lanes work safely and effectively in many cities in Europe, for example.  However, many officials here want to copy the separated sidepath aspect of the European style facilities without also copying the dramatic changes to intersection signals, timing, and flow that make the European facilities safe. We have never yet seen a proposal in Missouri to implement even a fraction of the intersection treatments that are common on separate paths in Europe--and it takes all of the treatments to make these facilities safe.

There is a fourth point:

4. We appreciate and encourage the building of wide sidewalks for a number of reasons. However, wide sidewalks should *never* be designated as bicycle facilities. See below for the reasons.

This page from transportation researcher Paul Allen summarizes the issues and research in a concise and understandable way:

The evidence that bicycling on sidewalks and similar facilities is more hazardous than bicycling on streets is overwhelming. . . .

[In Finland research found] Higher car-bike collision rate for one-way sidepaths compared with streets, even though pedestrians are prohibited from the sidepaths. Higher rate yet on sidewalks. Rate on sidepaths 4 times as high as on paths away from streets. . . .

Failure to meet the guidelines has led to multi- million dollar judgments against agencies. Here are a few important tips from the current AASHTO Guide:

1. Don't put two-way bikeways on one side of a street. Such facilities cause serious conflicts at intersections and driveways. Two-way bike lane use has led to a number of fatal head-on collisions [ie, between two bicyclists, as well as between the adjacent motorized traffic and sidepath users]. And such facilities encourage wrong-way riding.
2. Don't designate sidewalk bikeways. These also cause serious car-bike conflicts at intersections and driveways, as well as conflicts between bicyclists and pedestrians. Eugene, Oregon, and other cities have found that sidewalk bikeways have extremely high accident rates.


The KCAPWA bicycle facility guidance has this to say:


Page 24:


Due to safety considerations, sidewalks and walkways immediately adjacent to a roadway are not recommended for designation as bicycle paths or multi-use trail facilities.

Page 26:


Problems with paths immediately adjacent to roadways are summarized below and discussed in greater detail in AASHTO:
1). They require one direction of bicycle traffic to ride against the flow of motor vehicle traffic, contrary to normal rules of the road.
2). Bicyclists approaching and leaving the path tend to travel on the wrong side of the street, a major cause of bicycle/motor vehicle crashes.
3). At intersections, motorists often do not notice bicyclists on adjacent paths.
4). Signs posted for roadway users cannot be seen by bicyclists traveling against traffic.
5). When constructed within a narrow road right-of-way, shoulders are often sacrificed, thus decreasing the safety for roadway users.
6). Many bicyclists will use the roadway instead of the shared use path because of convenience or safety.
7). Bicyclists on the path must stop or yield often, while bicyclists on the roadway usually have priority over cross traffic. Bicyclists frequently ignore yield and stop signs.
8). Stopped vehicles exiting side streets or driveways may block the bike path crossing.
9). Barriers are often needed between the path and street, and may create additional obstructions and maintenance problems.
10). Bicyclist flow is complicated at intersections because it is contrary to the normal flow of vehicular traffic, pedestrian flow further complicates this design and creates confusion.


What does the AASHTO Green Book say?



Page 33:
In some cases, paths along highways for short sections are permissible, given an appropriate level of separation between facilities. [Example shown.] Note that the facility shown here is separated from the highway by a barrier, and there is no cross traffic. These provisions avoid hazards of car-bike collisions.
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At intersections, motorists entering or crossing the roadway often will not notice bicyclists approaching from their right, as they are not expecting contra-flow vehicles. Motorists turning to exit the roadway may likewise fail to notice the bicyclist. Even bicyclists coming from the left often go unnoticed, especially when sight distances are limited.
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Many bicyclists will use the roadway instead of the shared use path because they have found the roadway to be more convenient, better maintained, or safer. Bicyclists using the roadway may be harassed by some motorists who feel that in all cases bicyclists should be on the adjacent path. [Bicyclists' experience says this is VERY true and this is a VERY important consideration for the on-road bicyclists who ride 80% of the bicycling miles that are ridden.]
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Although the shared use path should be given the same priority through intersections as the parallel highway, motorists falsely expect bicyclists to stop or yield at all cross-streets and driveways. Efforts to require or encourage bicyclists to yield or stop at each cross-street and driveway are inappropriate and frequently ignored by bicyclists. [See this photo that illustrates the problem: http://bikexprt.com/massfacil/capecod/rte28.htm#stopsign ]
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For the above reasons, other types of bikeways are likely to be better suited to accommodate bicycle traffic along highway corridors, depending upon traffic conditions. Shared use paths should not be considered a substitute for street improvements even when the path is located adjacent to the highway, because many bicyclists will find it less convenient to ride on these paths compared with the streets, particularly for utility trips.
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Page 20:
In general, the designated use of sidewalks (as a signed shared facility) for bicycle travel is unsatisfactory. (See Undesirability of Sidewalks as Shared Use Paths, page 58.) It is important to recognize that the development of extremely wide sidewalks does not necessarily add to the safety of sidewalk bicycle travel, since wide sidewalks encourage higher speed bicycle use and increase potential for conflicts with motor vehicles at intersections, as well as with pedestrians and fixed objects....

Additional points made by Paul Allen:


In general, the designated use of sidewalks (as a signed shared facility) for bicycle travel is unsatisfactory. (See Undesirability of Sidewalks as Shared Use Paths, AASHTO Green Book, page 58.) It is important to recognize that the development of extremely wide sidewalks does not necessarily add to the safety of sidewalk bicycle travel, since wide sidewalks encourage higher speed bicycle use and increase potential for conflicts with motor vehicles at intersections, as well as with pedestrians and fixed objects....

Sidepaths are located where sidewalks usually are, and are used as sidewalks. The distinction which the Guide makes between sidewalks and sidepaths is largely academic. . . .

One goal of building trails is to provide a pleasant, quiet and scenic recreational bicycling experience. This goal is much better served by trails away from roads. . . .

Again, the reason experienced bicyclists are so insistent on these points is because they exactly correlate with our direct experience in using these facilities. They are dangerous for the reasons given. They do have the conflicts exactly as described, especially at driveways and intersections. They do encourage motorist harassment of bicyclists who choose to use the roadway because they know it is legal, safer and also much faster and more convenient. Study after study has shown that the "sidepaths" are more dangerous and inadvisable.

Many communities and states have gone down the path of installing the sidepaths as a matter of course, only to be hit with liability lawsuits and studies showing that the injury and death rates are much higher on the sidepaths. Then these communities and states have moved away from providing this sort of sidepath and into the mainstream of bicycle accommodation--which is on-street bicycle accommodation in and along roadways, and good, well-designed trail facilities in those places--like rail corridors and streamways--where trails can be designed to truly avoid conflict with motorized traffic.

It is sad to see Kansas City moving down that same false course of assuming that installing these dangerous and obsolete sidepaths along roadways is a good and safe solution--and should become our "default" solution.

And then twenty or thirty years down the line what we are going to find when we do that is that same thing that every other community has found--they are not good facilities, they are not safe facilities, they do not encourage more bicycling or safe bicycling, and they create a serious liability problem.

And then we have to start over from the beginning and do it all the right way.

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