The poetry of The Greater Marin

You may not know it, but The Greater Marin is on Twitter. It’s fun, really, to get in touch with people who agree and disagree with me from all over the world. Follow me, if you don’t already.

A new tool turned all these tweets into semi-coherent poetry. The result made me smile, so I thought I might as well share.

S!@# Together

North San Jose neighborhood
And design for your speed limit!
That does not sounds good.

Police, and idiot pedestrians.
Buses, like the GOOG shuttles:
Heh. Vegans.
Urbanist world: cars uber alles.

Inane of nuances of Marin politics.
With the new barrier, not less.
Hearts drown performance metrics.

The county and bring up some gold.
Napa, Capitol Corridor, and Marin.
Not smaller. Just slower and cold.

We’ll be back Monday, but if you can’t wait, find me on Twitter.

More people are speeding on the Golden Gate Bridge – here’s why


The new barrier and the bridge during closure. Image by David Yu, on Flickr

When the new Golden Gate Bridge barrier opened, it was heralded as a new age of safety, but there were rumblings of problems immediately. Bridge Manager Kary Witt was quoted as saying, “I do think everyone is driving too fast. Everyone needs to slow down.” A few days later, he was rather more forceful: “We’re seeing too many drivers driving 20 to 30 miles over the speed limit. It’s completely unacceptable.” While the district seems to have been caught off-guard, this was an entirely predictable result.

Keeping roads safe is one of the most important tasks traffic engineers have. To do this, they will often try to improve a road’s safety by making it more forgiving of driver error: make the lanes wider, smooth out the curves, remove trees, and add median barriers. But this sort of improvement assumes that people drive a set way without regard to their environment.

This is not true. People drive as fast as feels safe, and they subconsciously react to visual cues to tell them what that speed is. Have you ever driven along a road at what felt like a comfortable speed, only to find that you were going 55 in a 35 zone? You were a victim of this subconscious pressure, called risk compensation.

By removing dangerous obstacles, engineers will often paradoxically make a road less safe by encouraging higher speeds. In a limited-access highway this might be okay, but on roadways that aren’t limited access – like the Golden Gate Bridge – it can create a dangerous false sense of security.

This is precisely what is happening on the bridge. Before, drivers on the bridge had a very visible cue that danger was omnipresent as traffic whizzed by in the opposite direction just a foot away. People would drive slower to ensure they had control of their vehicle and wouldn’t accidentally drift into traffic. They also had to navigate the very tight space between toll booths, slowing traffic further.

By removing the toll booths and adding the center barrier, the bridge district has lowered the perceived danger of crossing the bridge. This has encouraged drivers to drive faster, which has resulted in more crashes.

This is not a limited access roadway, either. There are driveway entrances and exits at the Toll Plaza and at Vista Point. Pedestrians and bicyclists cross the bridge on its sidewalks. This is a recipe for disaster.

It is perhaps understandable that the district would choose to spend millions on a median barrier. It was a harrowing crossing, and I know I never drove in the left lane if I could avoid it. But it is baffling that the bridge district was apparently unprepared for higher speeds as a result of this change.

There is a lesson here: traffic speed follows design. If towns and cities in Marin want to reduce speeds and increase safety, it must design roads that encourage people to follow the desired speed. The Golden Gate Bridge District has done the opposite, telling people to go one speed while silently encouraging them to go faster. If it’s serious about keeping speeds down, it won’t rely simply on enforcement to keep speeds down but will also seek design solutions.

A third lane on the Richmond Bridge is just a bandage

from MTC

from MTC

The push for a third lane to Richmond has sucked a lot of the air out of the conversation over Central Marin traffic. Cut-through drivers from San Francisco to Richmond are taking up all the space in Larkspur and causing horrific traffic. Thanks to induced demand, however, the third lane will likely fill up soon after it opens and we’ll be back to the same old story.

The most common way to think of traffic is as a gas that fills the space it’s given. No matter how much you build, there will always be traffic to fill it. This couldn’t be more apt for the situation faced by the Richmond Bridge.

Right now, for cut-through San Francisco-to-East Bay commuters, the Marin route is the fastest and cheapest way to get home. These drivers may have to deal with congestion and delays on Sir Francis Drake and 580, but it’s less than what they’d have to deal with on 80 and the Bay Bridge.

If we solve the problem and open a new lane on the Bridge, we’d reduce congestion in Marin enough that we could declare victory… until more people saw that it was a less-congested route than 80 and the Bay Bridge and switched. Either this area will return to its present levels of congestion, or the congestion will migrate to another bottleneck further south in the system, or some measure of both.

This is a much larger version of a problem faced by Los Angeles suburbs, where cut-through drivers, guided by their GPS, take surface streets to escape congestion on freeways. Delays become as bad on surface streets as on the freeway.

If congestion returns to Larkspur Landing, then the widening will simply buy us a few years of peace. If it causes another bottleneck, we’ll have bought some peace to Larkspur Landing at the cost of congestion elsewhere. If it’s both, then nobody wins.

Longer-term solutions depend on which outcome occurs; let’s look at each in turn.

Congestion comes back to Larkspur Landing only

If this occurs, the only real solution is to keep traffic on the freeway as long as possible by installing a proper 101-580 interchange in San Rafael. This interchange has been proposed before, but community opposition to a towering flyover connecting westbound 580 with southbound 101 scuttled the project. If the same opposition arises again, it might be worthwhile to simply remove that aspect and only do the eastbound 580 to northbound 101 aspect.

For now, at least, Caltrans ought to remove signs at the Sir Francis Drake Boulevard exit indicating that that is the way to 580.

Congestion occurs elsewhere in the system

The most likely location for congestion to occur is south of Marin City: on the Waldo Grade, Golden Gate Bridge, Lombard, or Van Ness, all of which are good targets for transit. Both Marin commute trips and local San Francisco trips are relatively easily served by transit. The upcoming Van Ness BRT line will make a big difference to that corridor, and an extension onto Lombard would help both GGT and Muni riders. Extending the HOV lanes onto the Waldo Grade by converting one of the through-lanes would speed transit and encourage carpooling, also helping alleviate congestion.

Alas, transit sometimes functions like adding more lanes: the amount of congestion stays constant even while the transportation capacity of a road to move people increases. At least we can comfort ourselves that fewer people will experience congestion from behind the wheel.

Congestion occurs both at Larkspur Landing and elsewhere

If this occurs, then planners will need to employ both solutions: add the interchange and improve transit.

The only permanent solution

The rub, of course, is that congestion is ultimately not a solvable problem without an economic downturn. Houston, Seattle, Los Angeles – all have tried to fix congestion by increasing roadway capacity, and none have succeeded. Anthony Downs, in his 1992 book Stuck in Traffic, said that widening a freeway doesn’t work thanks to what he called a “triple convergence”:

In response, three types of convergence occur on the improved expressway: (1) many drivers who formerly used alternative routes during peak hours switch to the improved expressway (spatial convergence); (2) many drivers who formerly traveled just before or after the peak hours start traveling during those hours (time convergence); and (3) some commuters who used to take public transportation during peak hours now switch to driving, since it has become faster (modal convergence).

The only way out is to view road space like a resource, and to price it as such. Jarrett Walker describes it thus:

Fundamentally, congestion is the result of underpricing.  If you give away 500 free concert tickets to the first 500 people in line, you’ll get 500 people standing in line, some of them overnight.  These people are paying time to save money.  Current prevailing road pricing policy requires all motorists to act like these frugal concertgoers.  Motorists are required to pay for road use in time, rather than in money, even though some would rather do the opposite and our cities would be safer and more efficient if they could.  Current road pricing policy requires motorists to save money, a renewable resource, by expending time, the least renewable resource of all.

For the Bay Area, this would mean varying bridge tolls during the day so that congestion never builds up. Downs’ triple convergence would work in reverse.

With a rush hour 80 and Bay Bridge free of congestion, cut-through travel would be much less attractive for Contra Costa commuters. Those that still made the journey would likely not be enough to congest 101 at all.

But before then, we have a third lane and an interchange to try.