There doesn’t appear to be a lane width addendum in the on-line version of the 2009 MUTCD, or if there is it doesn’t contain the term “lane width” or “bicycle lane.”

Reading more of the information on WSDOT’s site, it looks like they might be taking their lane widths from AASHTO, whose current guide for bicycle facilities does specify 4-foot bike lanes on streets.

Roads open to bicycles have to meet bicycle standards.

Bike lanes on roads have lower standards than bicycle-only facilities, because roads have an alternative for the cyclist. On a road, when a 4-foot-wide bike lane is blocked or dangerous, the cyclist can simply move into the general-purpose lanes.

On a segregated bicycle facility, there’s no general-purpose lane to move into, so the bike path itself must be wide enough for safety.

If a bike lane is part of a wider roadway, it only needs to be 4 feet wide.

If it’s a bike-only facility, it must be at least six feet wide.

If they’re physically segregated from the general purpose lanes, AASHTO guidelines and WSDOT standards do not allow 4-foot one-way or 8-foot two-way bicycle paths. The 4-foot minimum applies to bicycle lanes that are part of a broader roadway, where cyclists can merge out of the bike lane to avoid hazards.

If the bike facility is a physically separate path, rather than a painted lane on the road, WSDOT minimum width is 6 foot one-way, 10 foot two-way.

So the bi-directional version is perhaps a bit of a vestige of the previous investigations. Some of the advantages of the bi-directional approach is more efficient use of the ROW, since there’s not a ton of space. Coupling the bike lanes eliminates one of the shy zones. The planted strip between the parked cars and bikes was a bit of a last minute add. We discussed raising the bike lane to sidewalk level, which I think has many merits and would make the 4′ bike lane widths less critical.

That said, in our next go around, we’ll definitely show a version with separate bike lanes, as well as center platforms.

As for narrowing sidewalks to increase the width of the bike lanes, that is completely counter to the ideas we are pushing. If anything, we should look to expand the pedestrian realm. It’s not just about the streetcar. Nor is it just about cycle tracks. Instead, it’s about the opportunities presented to re-envision what can be done with the ROW through the introduction of the streetcar, which includes providing opportunities for both bicycles and pedestrians. If that means the bikes in the bike lanes need to go a bit slower, I am fine with that. Calming auto traffic and making the environment more hospitable to pedestrians is one of the intentions of the proposal. Calming auto traffic to allow unfettered bike traffic is again counter.

(1) Widths
The desirable width of a shared-use path is
12 feet. The minimum width is 10 feet. ….
Use of 12- to 14-foot paths is recommended
when there will be substantial use by bicyclists,
or joggers, skaters, and pedestrians.

8 feet is too narrow for a bi-directional path. As much bike and pedestrian traffic as you see on Broadway today, I’d expect even the usual 10-foot standard would be too narrow for safety.

One-way bicycle paths can be as narrow as 6 feet (plus shy distance on the sides), so there could be room to squeeze them in with narrower sidewalks and planting strips.

The rendering also doesn’t have compliant shy distance on the sides of the path; it appears to show non-compliant bollards in the path; the intersection treatment lacks required signage and markings. But that doesn’t necessarily mean it’s a dangerous and untenable plan — it’s an artistic rendering that also leaves out wheelchair ramps, parking signage, bike racks, and all sorts of other details that would have to be in the real design.

But it is a good heads-up to cyclists to take a closer look at whatever designs do come forward, since so many cycling facilities are designed by and for non-cyclists.