An Open Letter to the City of St. Louis
The rebuilding of the Grand Boulevard bridge over the Mill Creek Valley will be done soon. It is scheduled to reopen some time this summer, maybe as early as June. Roger Allison, chief engineer of the design division for the city’s Board of Public Service, emailed me the signing and striping plans for the new bridge (here is a second link to the road sections). The current plan is to stripe six-foot shoulders on the new bridge, which would someday become road-edge (or “gutter”) bike lanes. Bike lanes are not due to be striped immediately, because there are no bike lanes at either end of the new bridge.
Here’s hoping that the City of St. Louis will never put bike lanes on the bridge! For a whole host of reasons, segregated bike lanes are not the best or safest solution to encourage cycling on arterial roadways. Earlier this week I sent Roger a letter, explaining why, and offering ideas for alternatives:
Thank you for forwarding the signing and striping plans for the Grand Viaduct reconstruction. After reviewing, my request is this: Rather than creating segregated infrastructure for bicyclists on the new Grand Viaduct, would the City of St. Louis consider using integrated solutions instead?
Before offering solutions, I’d like to review the issues with segregated, or curbside/”gutter” bike lanes on arterial roadways:
- On a road where vehicles typically travel 35 mph or faster, motor vehicles push trash and debris into road-edge bike lanes, making them dangerous to use
- Curbside bike lanes present conflicts at intersections between motorists and cyclists. For example, motorists may need to turn right while cyclists are going straight, or cyclists moving ahead in a bike lane may be screened by slower-moving motor vehicles and therefore may not be seen by oncoming left-turning motorists
- When bike lanes end, cyclists often do not know how to safely re-integrate with other traffic
- There is the cultural pressure of having to use a bike lane, even when it forces cyclists to ride dangerously close to fast-moving vehicles, or may be debris-strewn, or may not the best lane to serve one’s destination. Once a roadway is striped with a bike lane, fellow road users may not understand and may take offense when cyclists must leave that bike lane (to avoid an obstacle or intersection conflict, or to make a left turn)
Advocates mistakenly think that the mere presence of a bike lane on an arterial roadway will reduce motor vehicle speeds on that roadway. This is not true. Here is a link to an article with data from the Institute of Traffic Engineers reviewing this idea, as well as local “on the ground” experience. In fact, a bike lane on an arterial roadway is more likely to make cyclists in that bike lane irrelevant to motorists.
What to do? I am not an engineer—just a user!—so have copied Paul Wojciechowski, the engineer behind the St. Louis Bicycle Master Plan. We are fortunate in St. Louis to have Paul, because he understands the inherent flaws of on-road bike lane design (though he also must have the thankless position of hearing the loudest clamoring for such facilities).
It would be safest for all users if the City would discard the idea of striping bike lanes on the new Grand Viaduct, and instead stripe the bridge with one extra-wide lane in each direction. For example, where two lanes in each direction are proposed to be 12 feet wide each, with a six-foot bike lane on the edge of the road, stripe instead as 12/18 (with one lane that is 12 feet wide and one lane that is 18 feet wide). The section where there are to be “12/15″ lanes, stripe instead as “11/16.” This would allow sufficient passing clearance, and result in the collection of far less debris at the edge of the roadway.
It is my understanding that traffic engineers are reluctant to stripe 16′ and wider lanes, because they can end up functioning as two lanes. In reality, this does not happen. For visual evidence, see “Four Faces of Orange Avenue.” Orange Avenue is an arterial in Orlando, FL. (We have no streets that compare exactly, but Orange Avenue probably is best described as being similar to our Market Street if it somehow morphed into Kingshighway as it left Downtown.) A 19-foot-wide lane begins at 1:55 in the video. Motorists do not double up in wide lanes because they are not comfortable driving inches from each other’s vehicles, especially when large vehicles like trucks and busses use the road. Ironically, motorists have no problem driving that close to cyclists who are in a bike lane, as this video also shows.
I also understand that political pressure may be too great to *not* stripe special bicycle facilities on the new bridge. In this case, the best tools of which I am aware that would be appropriate for the Grand Viaduct are shared lane markings (“sharrows”) and the white information signs approved by the Manual on Uniform Traffic Control Design: “Bicycles Allowed Full Use of Lane – Changes Lanes To Pass.”
Perhaps Paul is aware of other solutions that will not violate what should be the First Commandment for 21st Century traffic engineers: