• Apr 3, 2006

A new study of San Francisco's high occupancy vehicle (HOV) lanes has revealed something disturbing: more congestion. According to researchers at UC Berkeley and Cal State University, East Bay, in a 100 mile sample section of freeway, HOV lanes have counter-intuitively led to an increase in traffic congestion.

The study utilized data collected from sensors embedded in the pavement over 4.5 years between 2001 and 2005. As San Francisco's HOV lanes are only active for 8-10 hours per day, traffic could be measured both with and without the restriction in place, allowing for the comparison.

What they found was that not only was there no increase in carpooling, but that that when HOV lanes were 'active',  traffic capacity decreased by 20-percent by increasing congestion on other lanes. A report from 2005 also noted that  in areas where HOV lanes are not separated from general traffic, accident rates increase by some 50-percent.

[Sources: TheNewspaper.com, CalAcademy.org]

 

 



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  • 32 Comments
      • 8 Years Ago
      > From that response, I take it you don't
      > even live in LA.

      I live in Detroit metro, which has the largest population of Arabs outside of the Middle East, not to mention Poles and Italians and almost every other ethnicity you can think of. So there's no shortage of immigrants here. I'm the son of immigrants myself.

      I've got a great idea: why don't *you* go back to wherever *your* people emigrated from! That would solve your problem, wouldn't it?
      • 8 Years Ago
      I have to side with Kevin. Comparing rush hour to non-rush hour traffic is poor analysis. You do not have a proper control variable. For instance:

      "The study found that at 60 MPH, an HOV lane has a maximum flow of 1600 vehicles per hour compared with 2000 for the general purpose lanes. Researchers used an estimate of 1.3 or 1.4 occupants per vehicle in the general purpose lanes to calculate that HOV lanes are not able to transport more people per hour than a general purpose lane."

      Just a little math shows that 2000*1.4=2800 people/hour. The HOV lanes only need 1.75 people/car to beat that. If the HOV system requires a driver + 3 slugs, the single lane is carrying more people than twice as many lanes of regular traffic.

      The other issue is whether the HOV lanes allow ULEV vehicles to avoid occupancy restrictions or not. Now the HOV lanes back up as badly as the standard lanes because ULEV drivers don't bother to pick up slugs.
      • 8 Years Ago
      About time they realized this. How long does a social experiment have to fail before they admit it is a failure and makes traffic worse?
      • 8 Years Ago
      "12. Here's an idea that might actually work: forbid SUVs traffic from all lanes but one."

      Yeah, and how would that work, exactly?

      You want an real idea that might actually work? Encourage telecommuting and staggered commute times. If you could take even 15% of the cars off the road from 7:30-9:30 and 4:30-7:00, there wouldn't BE traffic. Every day would be like Columbus Day or President's Day or one of those other holidays that schools and banks get off but no one else does.

      On top of the obvious benefit of decreasing traffic congestion, everyone would see better gas mileage, emissions would be lower, etc etc.
      • 8 Years Ago
      I have been saying this for YEARS. If you limit a particular lane to a smaller portion of the population, all you are doing is reducing the bandwidth of your highway.

      The reality is that NOBODY, not even "progressive" San Franciscans, are going to postpone thier drives and find somebody to ride with just to use a special lane.
      • 8 Years Ago
      What's San Francisco's regional public transportation like? Do they have subways like Boston and New York? That's by far the best way to keep congestion to a minimum.
      • 8 Years Ago
      D'uh is right. Let's see, we take this tax money to cut a lane's utilization in half, then wonder why traffic is worse than it was before. I wish the folks around DFW would figure this out and open these lanes to the public that paid for them. Maybe somebody should study how much gas THAT would save.
      • 8 Years Ago
      This report is faulty. Of course congestion is going to be higher when the carpool lane is in use. Its in use at 6-10AM and 3-7PM, which last time I checked were the busiest parts of the day for traffic anyway. The only way to really test if it made it worse would be to actually remove the restriction on the lane for a week or two and then take some data. Taking data from different parts of the day is like comparing apples and oranges.
      • 8 Years Ago
      > You should see Los Angeles! I hate it here.

      > Illegal immgrants go back to Mexico
      > and fix up your own country.

      >I'll ignore the xenophobic nature of your comment and >point out that recent immigrants are more likely to >use public transportation, more likely to work during >off-peak hours, and less likely to contribute to >congestion on the highway during rush hour. So you >can kick out all the immigrants you want, it's not >going to solve the problem.


      From that response, I take it you don't even live in LA. You wouldn't know. Not all illegals use public transportation. Infact there is plenty fo them with automobiles. On a Mexican holiday the highways in LA flow freely. I've been here for over 3 years and know the difference you don't know. When you have live here for a few years then lets talk. Otherwise, shut up.

      • 8 Years Ago
      Please note that HOV is not a failure everywhere; the HOV lanes in the Northern VA / DC plex are amazingly successful - leading to something unique to the area (AFAIK, anyway), the slugline (AKA spontaneous carpooling) - a system where people actually pick up (semi-)strangers so they can make the HOV restrictions. It helps that the HOV lanes are entirely separated from normal traffic (Well, I-66 inside the beltway is ENTIRELY HOV during rush hour)

      See http://en.wikipedia.org/wiki/Slug_line for details
      • 8 Years Ago
      Here's an idea that might actually work: forbid SUVs traffic from all lanes but one.
      • 8 Years Ago
      Duh! Take a lane or two basically out of service and of course it increases congestion. The dumbing down of America, then we need a research project. Things can't get more simple, ask the drivers, driving it everyday, take a few digital phots, befor-after, done.
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