Tonight, the county will hold a hearing on rebuilding and enhancing Sir Francis Drake Boulevard from the Ross border to Highway 101. (Details: 7pm, College of Marin, Kentfield Campus, Fusselman Hall 120, project site here.) This provides a golden opportunity for Marinites to transform and improve one of Central Marin’s most important streets to better serve people in cars, on bikes, on buses, and on foot.

Congestion sucks

From a workshop survey in late October, people called traffic congestion the worst problem along the corridor, and it’s not hard to see why. Drivers have to deal with stop-and-go traffic all along Bon Air Shopping Center to 101 in the morning, and a number of intersections are overloaded at the same time. This, of course, sucks for drivers and bus riders alike, as well as anyone living, working, or shopping along the corridor.

Walking and biking along Drake is also a pain. As a 35-mph roadway with narrow and sometimes nonexistent sidewalks, it is impossible to feel welcome either on foot or on bike, a major problem for kids and their parents, as well as those who don’t have their own car.

But Sir Francis Drake isn’t just a traffic sewer. North of Bon Air, Drake serves as a main street for Kentfield and College of Marin, and a vital access to Bacich Elementary and Marin Catholic High schools. How to connect these uses together with the high-capacity roadway to the south is a quite challenging question.

Design advice

Though it’s important to lay out priorities before tackling a planning problem, along this corridor the traffic concern is overriding. So, instead of laying out priorities, let’s lay out the tools in our toolbox:

Intersection Design
Segmenting travel modes
Adding car lanes

Each of these will relieve some stress on the roadway, either by improving volume (the second two) or easing traffic flow generally (the first one). We also want to make sure that any additional lanes are consistent – it’s a bad idea to start a lane and then end it.

The presentation in October split up Drake into 4 segments: Ross Limits to Broadway; Broadway to Wolfe Grade; Wolfe Grade to El Portal; and El Portal to 101. Each segment’s right-of-way (property line to property line) is a different width, which makes planning consistently difficult.

Nevertheless, I’m unimpressed by the solutions presented. Unprotected bicycle lanes on a 35mph road will simply never be used. This might be excusable if there weren’t space for buffers, but a huge amount of space is dedicated to a center turning lane and median. As well, 11-foot lane widths, though a huge improvement to the 15-21-foot lanes, are wider than a city street ought to be. Lanes of 10 feet should be standard. For comparison, freeway lanes are generally 12 feet wide.

Here are current conditions, the county’s ideas, and my own ideas. Note that despite having protected bike lanes, there are no proposed eastbound traffic lanes cut, meaning the roadway's throughput will remain enhanced where it is most under pressure.

Segment 1: Ross Limits to Broadway

Hover over each of the following to see commentary.

Existing Conditions

The existing conditions have some way-too-wide traffic lanes and a very wide median.

Bike Lane Proposal

Every lane has 11 feet of width, but the bike lanes are right in the way of people opening doors or making unsafe left turns.

Protected Bike Lane Proposal

This plan does narrow the median a bit, but in return the bicycle lanes are protected from traffic by both parked cars and a three-foot barrier. Traffic lanes can maintain their 11-foot width, if this is legally important (as it sometimes is).

Segment 2: Broadway to Wolfe Grade

Hover over each of the following to see commentary.

Existing

Proposed

Protected Lane Proposal

The narrower right-of-way means there is less space for everything we might want, so the median is cut even more.

Segment 3a: Marin Catholic

Hover over each of the following to see commentary.

Existing

Two lanes each direction and some heinous sidewalks.

Proposed

This proposal cuts some Marin Catholic parking, which may not be acceptable to the school. It also includes three lanes in either direction, which might not be needed.

Protected bike lane proposal

This proposal adds a traffic lane at the expense of the center turn lane. Given that poor traffic doesn't start until further south, the turn lane may be more important than the extra traffic lane.

Segment 3b: Bon Air Road to El Portal

Hover over each of the following to see commentary.

Existing

Some very wide lanes and right-of-way wasted on scrubby slopes.

Two Lane Bike Lane Proposal

Adds bike lanes and sidewalks in place of some of the slope and scrub.

Protected Bike Lane Proposal

Cuts out the slopes entirely to add a third eastbound traffic lane.

3 Lanes EB, Sidewalks

Sidewalks, Three Lanes Proposal

Cuts the bike lanes in favor of wider sidewalks and a third traffic lane.

Six Lanes

Cuts sidewalk and bike improvements in favor of two new lanes going in either direction. Given that this isn't proposed elsewhere, could cause merging issues heading west.

Segment 4: El Portal to Highway 101

Hover over each of the following to see commentary.

Existing

More very wide lanes and poor options for people on foot or on bike.

Multi-Use Path Proposal

Adds a protected multi-use path to the eastbound side of Drake, along with another traffic lane.

Protected Bike Lane Proposal

Maintains the protected lanes and adds a third lane. Though it shows up as a center-turn lane, the lane would work as it does now, alternating between planters and dedicated turn lanes.

Multi-Use Path Proposal 2

Adds the path to the westbound side of Drake. Given the very difficult off-ramp from 101, and the lack of stuff on that side of Drake, this doesn't seem to make sense.

Vehicular Preference Proposal

Creates a six-lane arterial road for this stretch of Drake and cuts bike lanes.

Protected bike lanes drive bicycling use

The reason I have added protected bicycle lanes to each segment is because they push for a relatively fantastic increase in cycling use. At the moment, just 1 percent of users along Drake are on bike, probably in part because of how difficult it is to bike along the route. Boosting that percentage even a bit - to 5 percent - could do a lot to cut down on traffic, especially around school times.

Congestion is the result of a tipping point, where the traffic levels rise just a bit too much, causing speeds to fall off a cliff. Taking just a few trips off the road can have an outsize effect on congestion levels. When paired with a wider road, as both the county and I propose, it should do wonders to cut down on traffic. The lanes may also soak up some of the induced demand from driving that occurs whenever a road's capacity is increased, prolonging the usefulness of this improvement.

Intersection Design

For each of the proposals I generated, intersections should be redesigned to allow the easy flow of people in all modes. Check out the full presentation for info on the proposed intersections, which do a great job for pedestrians, but they are insufficient for protected bicycle lanes. I've uploaded some options from the NACTO bicycle guide below.

If you're going to go to the meeting at this last minute - I myself only found out about it today - then get yourself to College of Marin at 7pm, Fusselman Hall 120.