Public Comment

Missing the Facts on Marin

By Preston Jordan
Thursday February 25, 2010 - 09:10:00 AM

In the Jan. 14 Planet, Zelda Bronstein relays that Berkeley's report on the Marin Avenue reconfiguration concluded that motorist speeds were not reduced (“Save the Alameda” ). This same result was found in Albany where I live. The untold story is that the number of motorists on Marin was significantly higher during the pre-reconfiguration survey in 2005 (22,453/day in Albany) than in the post-reconfiguration survey in 2006 (17,789 in Albany). Fewer motorists means most can and do choose to drive faster. 

This is not a case of ah-hah, the motorists switched to other streets, as so many argued would happen. In fact, the volume of motorists decreased on all the other streets surveyed also (which were included to catch just such a diversion should it have occurred). Rather the consultants concluded that this network-wide decrease occurred because it was pouring rain during the post-survey as compared to the sunny weather during the pre-survey. 

Albany performed a more comparable speed survey in 2007. On that day there were 19,483 motorists on Marin, still fewer than in the pre-survey, but more than the 2005 post-survey. Speeds decreased nonetheless. Half of motorists were driving faster than 30 miles per hour (mph) in 2005. This speed dropped to 27 mph in 2007. Fifteen percent of motorists were driving faster than a whopping 37 mph in 2005 (the speed limit is 25 mph). This speed dropped to 33 mph in 2007. 

Some may say, so what? A speed de-crease of three to four miles an hour is insignificant. It is only a 10 percent decrease. Those who remember their high school physics may recall that kinetic energy is proportional not to velocity but to velocity squared. So decreasing the velocity of a motorist’s car by 10 percent decreases the kinetic energy involved by about 20 percent. This matters because it is the kinetic energy, not the velocity, that controls the severity of injuries to someone walking or cycling who is hit by a motorist. A 20 percent decrease is a big change viewed from this perspective. 

Ms. Bronstein cites the fatalities of two people walking across Marin struck by motorists after the reconfiguration as another argument why such reconfigurations are not worthwhile. She fails to mention that one fatality was due to a motorist turning left onto Marin from southbound Colusa hitting a person in the crosswalk. The other was due to a drunk driver hitting a person using a crosswalk. Ms. Bronstein is correct that the reconfiguration was ineffective in preventing these accidents. Preventing such accidents would require much more significant changes to the street. However Ms. Bronstein selectively left out the accident specifics to support her desired conclusion, which is just the opposite. 

I wish Berkeley the best in its deliberations regarding reconfiguring The Alameda. I hope that the decision will be based on sound data analysis and reasoning rather than data manipulation and fear-mongering, as was the norm when Berkeley attempted to reconfigure Claremont. It is worth noting that, despite that more recent history, Berkeley was a leader at one time, having pioneered street reconfigurations to reduce traffic lanes on Marin above Hopkins and Sutter/Henry south of the Solano Tunnel decades ago. 


Preston Jordan is a Berkeley resident.