Over the next few weeks, I aim to uncover the dust from all those great 1970s carpool studies and discuss how they do or do not relate to life in 2009. Finding this research has taken me from the basement of Stanford’s library to days of internet searches to uncover all the best carpooling academic literature. My grad professors would be proud; they pounded the tables about the importance of data.

Even before starting at Zimride this summer, I wondered if carpool services were worthwhile. Do they help the environment? Are they effective at saving people real sums of money, reducing congestion, or making life more pleasant? Would they pair your grandma and the lead singer of Metallica? Let’s hope not! Or poor Tessa would surely get a few more “customer service” phone calls. We all know how those old rideshare boards, don’t get much use. Out of 50k students at my Alma Mater, I don’t think there were ever more than 10 postcards for rides on the ride board. For all you whiz kids, that’s 0.02%, certainly a number that would get any TDM (Transportation Demand Management) director fired. Just to settle things, Zimride does a lot better than matching 10 rides per university!

Rideboards: 0 Zimride: 1

Then I looked for support in ivory tower research. It’s always best to start with summaries, that’s why you’re here, right? A great first start into understanding ridesharing was “The Determinants of Ridesharing: Literature Review” by Keith Hwang and Genevieve Giuliano (School of Urban and Regional Planning, University of Southern California, Working Paper, May 1990). These guys did a bunch of leg work for me, although my legs are getting pretty buff from biking 6 miles a day to/from the local Caltrain station to get to work!

A big ah ha moment came to me when I read “With matching services, employees rideshare approximately 10 percent more than without it within each size category of firm.”

Then I saw the data of how employees get to work at employers with over 10,000 employees. Only 11.15% of employees at firms without matching programs participated in ridesharing vs. 24.23% of employees at firms with matching programs. That’s a huge difference!

Single occupancy vehicle participation rates were also striking: 85.81% at those without matching programs vs. 74.74% for those with matching programs. Ok, so you’re probably thinking to yourself, those firms without matching programs probably have different efforts focused on TDM. Well, the participation rates of public transportation would be vastly different if that was the case. However, that’s not the case; public transit participation rates were 1.95% for firms with matching programs and 1.91% for firms without matching programs.

Case closed. Matching programs work and work really well.

Note: the above data was originally published by Ferguson, E. (1990a) “An Evaluation of Employer Ridesharing Programs in Southern California.” Transportation Research Record. 1280.