Thursday, January 28, 2010

E pur si muove
Casual Carpooling on the streets of America

One of the keys to sustainable transportation is to gain high quality mobility for people while reducing overall traffic. One way for doing this is to figure out how to get more people into fewer vehicles, efficiently. Fortunately there are many ways of doing this, not all of which take a lot of time to build and cost a bundle. Here is one example: casual carsharing. And despite the fact that it may seem a bit odd and marginal, as Galileo Galilei so famously put it: "E pur si muove" (roughly, "they do seem to be getting there"). Tne key to new mobility is to seek and combine large numbers of what may appear at first glance appear to be "small" things. Here's one that works.

Casual Carpooling, California, 26 January 2010

It’s not a system that anyone owns and operates, but it is a system that works. The casual carpools in San Francisco are an ongoing wonderment that keep on giving.

When I get to San Francisco I usually get out and count the casual carpools, at one pick-up point or another. For a couple of hours I sit in the cold morning and watch people walk up or get dropped off, then either line up and wait, or get into the front car in a line of waiting cars. These instant carpools then get to use the HOV lane and avoid the toll on the Bay Bridge, traveling quickly to their downtown destinations. I call it ‘flexible carpooling’.

I have counted carpoolers next to the Safeway at College and Claremont three times over the years: January 2007, May 2008, and today, January 26, 2010. Each time I am amazed anew at the quiet system that, I estimate, saves San Franciscans about 900,000 gallons of gas a year, and something in the order of $30 million in total costs. You can read how I made that estimate, presented as a poster at the TRB two weeks ago, here.

You can click on this link to see the chart that shows how the counts of casual carpoolers have changed over the years, including the count done in 1998 by RIDES for Bay Area Commuters, Inc.

The sweetest part of watching casual carpoolers is the ‘kiss and ride’. In its usual usage this term refers to a drop-off area at a park-and-ride. At the casual carpool line it is somehow more personal, as a couple walks up to the line, kiss, one gets into a car with a couple of strangers and the other turns and walks away, probably heading back to the home-office for the day. Today one kiss-and-walk-away-er was walking a dog.

You should know that this system is thought to be under threat. Tomorrow evening a decision could be made to charge the Bay Bridge toll to carpoolers. This might tip the economics such that drivers stop driving and instead take public transport (BART or AC Transit). On the other hand, it might result in a cost sharing arrangement in the casual carpools, perhaps riders giving a buck towards the cost of the trip.

The last time transport costs changed dramatically was in May 2008 when gasoline prices topped $4.00 per gallon. You can see from the chart that there was a big reduction in casual carpooling at that time. The number of drivers dropped. The line of people waiting for a ride was longer, and many more vehicles took three instead of the usual two riders. (Of course, since this was the only time I counted in May, perhaps that was the normal May pattern. In this unmonitored casual system there are no records of usage patterns that can be compared from year to year).

There is no certainty about what will happen if the toll is charged to casual carpoolers. The additional revenue that BATA will receive if the casual carpoolers continue un-abated will be in the order of $1.5 million. What we really need to do, as interested professionals, is make sure that we know what the impact is. There should be a reliable and complete count over the coming months, and again as soon as the toll is implemented, and again a few months later. The cost of these counts would be minimal, but the value in terms of insights into the impact of the change would be significant, and probably relevant for other jurisdictions.

The most mystical aspect of casual carpooling is the balance. Somehow without any website or fancy technology the number of cars that look for riders is about right for the number of riders looking for cars, even though when you talk to casual carpoolers they say they do not all do it every day. This morning there were 96 carpools formed, so nearly 200 riders got a quick trip to work from that location. This is similar to 2007, lower than 1998 and higher than 2008. Most of the time there was a line of cars waiting, so riders were well served. No one waited too long, and all cars took two riders, except for a couple of two-seaters. Think about how much effort would be put into making 96 three-person carpools in other systems. In the 1998 survey the authors estimated that 9,000 people were using the system each day.

My interest in casual carpooling is that it is a system we should nurture. Against all the odds, this system shows that people do not have to make pre-arrangements to share rides. It suggests a mechanism that could enable much higher HOV formation rates. It offers ideas that might be used to reduce peak hour congestion in lots of jurisdictions around the country.

# # #
Some references:
* On casual carpooling,
* On Slug-lines,
* More on casual carpooling,

About the author:
Paul Minett is co-founder of Trip Convergence Ltd, and co-inventor of flexible carpooling. Invented without knowledge of the slug-lines, flexible carpooling can best be described as a formalisation of that unique method of carpool formation found in Washington D.C. and the San Francisco Bay Area (also known as "casual carpooling"). Arguing that for more carpooling we need meeting places rather than databases, Mr. Minett has been making steady progress towards testing of this alternative mode.

Paul Minett,
Managing Director, Trip Convergence Ltd

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  1. This system is giving rides to about 12,000 people every day between two US locations. That is about 3 million trips per year if you allow that some of them use the system for the return journey as well.

    Paul Minett, New Zealand

  2. Dr S. L Dhingra , IndiaFriday, 29 January, 2010

    Car pooling /carsharing can marginally induce effective transportation sustainability provided it is planned to ensure security and reliability for either party.

    With best wishes and warm compliments,
    Dr S. L Dhingra
    Institute Chair Professor
    Transportation Systems Engg
    Civil Engineering Department
    IIT, Powai, Mumbai-400 076,India
    Phone:91-22-25767329(O), 25720001(H),
    25768329(H), 91-9820345493(Cell),,


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