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.

Slugging: Bringing Casual Carpooling to the North Bay

Casual carpooling, wherein strangers carpool with one another to and from job centers, could be viable in the North Bay, but it will take coordination from citizens and government to make it really take off.

When examining the modes of commuting, typically absent from the conversation is carpooling. Either it happens or it doesn’t, but governments and citizens will fixate on accommodating more traditional modes of transportation: single-occupant vehicles (SOVs, i.e., cars), buses, and trains, rather than actively trying to encourage carpooling.

There are a number of reasons for this, but I suspect a big one is that there is no ribbon to cut, no new lane or train to inaugurate. Another big one is the perception that carpooling only rests on social networks outside the reach of government intervention, where coworkers discover by happenstance that they live near enough to one another that carpooling becomes an option. Besides, interfering in carpooling takes attention away from the big capital projects that make headlines.

In spite of apathy from officialdom, the phenomenon of casual carpooling does arise in certain locales. Known in the Washington, DC, region as “slugging”, casual carpooling entails passengers forming lines at pickup areas, usually commuter lots or bus stops. A driver will approach the line, shout their destination (“Pentagon!” “Civic Center!”) and those bound for the area will hop in. It works both ways, and situating near bus stops gives passengers the option of a commuter bus if they’d prefer.

Casual carpooling gives drivers and passengers certain advantages over SOV driving. It allows them to use HOV lanes, saving time, and it allows passengers to save on driving costs such as gas and maintenance. For those who aren’t in a carpool, carpooling means there’s more for them: every passenger is one less car on the road and one less parking space taken. It’s a win for everyone. So why does it pop up in some locations but not others?

East Coastin’

The Washington, DC, region makes an interesting test case. Straddling as it does three states (DC, Maryland, and Virginia), we can see how different policies effect the outcome. Virginia has an active and large slugging community dating back to the 1970s, while Maryland’s community is relatively small. The principal difference, according to David LeBlanc, author of Slugging: The Commuting Alternative For Washington DC, is that Maryland uses HOV-2 lanes, where having only one passenger qualifies, while Virginia uses HOV-3 lanes, where two passengers are necessary to use the lane. He argues that HOV-3 lanes give passengers a sense of safety when getting into a car with a stranger, and spurs drivers to more actively pursuit warm bodies to fill their vehicles.

Dampers on casual carpooling include high-occupancy toll, or HOT, lanes, as Virginia will soon discover when its primary HOV corridor into DC is partially converted to HOT. If a driver can simply pay a toll to qualify, they will be less likely to detour to a slug line for passengers and clog the lanes with SOVs. The lack of HOV lanes, of course, will remove the incentive for the driver to pick up passengers as well.

North Bay Slugs

In other words, the North Bay, with its HOV-2 lanes that stop after Sausalito, is not ideally suited to casual carpooling. While Northern Virginia has an entire reversible highway dedicated to HOV-3 that extend all the way from suburbs to job centers in Arlington and the District, complete with their own exits and with limited access, the North Bay has only a single HOV lane in either direction that requires drivers to slow from top speed to the speed of traffic in order to merge over to the exit, and which stops before reaching either the East Bay or San Francisco. Although it’s conceivable that a small, Maryland-style community could spring up in the North Bay with the right tools – an app, say, allowing potential carpoolers to mark off their home and destination – true casual carpooling will require a bit more intervention at the governmental level. As with everything, there are cheap and expensive solutions.

On the cheap side, just switching our HOV lanes to HOV-3 would be a boon, giving drivers a greater incentive to pick people up. Following up the switch with congestion pricing on both bridges applicable only to SOVs would prove a high-profile shot in the arm for any casual carpooling system. Given the hubbub over the last attempt to institute congestion pricing on the Golden Gate Bridge, the press would be wonderful. Instituting a peak-only HOV lane on the southbound side of the bridge would be another major reward for carpoolers: no more waiting in line at the toll plaza. Instituting congestion pricing at the Sonoma/Marin border or just north of Marinwood* would stimulate casual carpooling among Sonomans coming to Marin – our largest in-commuting population – and would raise millions for transit projects between the two counties.

On the expensive side, CalTrans might consider combining Highway 101’s two carpool lanes into a single, reversible HOV freeway, complete with limited access and dedicated on/off ramps. This would make carpooling significantly safer and faster, and would have the added bonus of improving bus access along the freeway. The cost, however, would likely be upwards of $1 billion given the technical challenges of HOV exits and the cost so far just to extend regular HOV lanes.

It has been suggested that the app described above would help drive a casual carpooling renaissance, but the truth is that these networks typically form in response to everyday commute pressures – heavy traffic, centralized job centers – that ultimately come from structures either put in place by government or arising out of commuting physics. That’s not to say technology does not have a role to play – casual carpool networks often have websites to guide potential participants and there are a number of apps already in existence – but a truly robust system will be one that arises organically. Drivers will only take the time to pick up passengers when they can clearly see that it is worth their time or money to do so.

Casual carpooling in Virginia has been described as another transit system by the Virginia Department of Transportation, complementary to the existing Metrorail and bus systems. It certainly has a place in the highway-centered transportation systems of the US, but it will take work to implement in the North Bay.

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*Most freeway traffic in Marin actually comes from Novato, not from Sonoma; although instituting congestion pricing there would be a political nonstarter, it would make the most sense from a practical standpoint.

For information on casual carpooling in the Bay Area, RideNow.org has a website dedicated to the local network. For information on ridesharing in the Bay Area, you might want to look into eRideshare.com. For information on how the slugging system works in Virginia, local NPR affiliate WAMU aired an hour-long segment on the subject, while local transit blog Greater Greater Washington has a number of posts on the subject.

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