Does Money Reduce Single Occupancy Vehicle Trips?

TDM programs nationwide focus on modes of transportation, offering alternatives and subsidizing various programs to solve congestion and parking challenges from too many people using their cars alone. I argue that one easy way to curb congestion is simple: Money. Throwing money at the problem can significantly reduce SOVs, and this isn’t just my MBA candidate bias coming through: there’s real proof.

Thanks to the Victoria Transport Policy Institute (VTPI), I learned all about how money changes transportation behavior. If you have time to read all 70 pages in the report, go for it. While the report did note that “No single transit elasticity value applies in all situations,” it did find great commonalities.

VTPI discussed several models that “predict the travel impacts of a specific…program…These include the CUTR AVR Model (, the Business Benefits Calculator (BBC) ( and the Commuter Choice Decision Support Tool (” Most of these don’t seem that user friendly and the commuterchoice one doesn’t even seem to exist anymore. Either that or it’s painfully difficult to find.

Within this discussion of various models, I found this figure (figure 7) the most useful because it was simple and made sense. If someone pays $160 (1993 dollars) a month, less than 30% of people will drive alone. I sure would change my behavior for $237 a month (2009 dollars per inflation calculator).

Giving money away really seemed to do the trick. “Solo driving declined 17% after parking was cashed out (employees could choose cash instead of subsidized parking), as illustrated in Figure 8.” Also, the report discussed how these impacts “increase over time.”

Just by looking at this figure, it seems like carpooling is a clear winner when it comes to cashing out. That begs the question though, can you combine cashing out with a carpool service and high impact marketing campaign to produce even better results? To my knowledge no such study exists, but from the research I’ve seen so far, I’d place a big bet on that one.

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