Want your workers to drive alone to work? Offer them free parking; nothing groundbreaking there. This study [PDF] by Virginia Tech transport scholars Andrea Hamre and Ralph Buehler goes much further, of course, and yields surprising results, clearly illustrated in three charts that CityLab's Eric Jaffe constructs.
"Thing is, commuter benefits for everyone can end up being a loss for the city itself. That's because the lure of free office parking is so great that it not only neutralizes the other benefits, it actually entices some commuters into their cars and out of the alternative mode they might otherwise prefer," writes Jaffe.
At baseline, when employers offer no commuter benefits at all, the probability of driving alone to work is nearly 76 percent, with taking transit at 22 percent (see chart, orange dots). As expected, when a company offers only free parking and no other benefit, the probability of solo-driving nearly hits the roof, reaching 97 percent (blue). Similarly, when a company offers only transit benefits and nothing else, probability of taking the bus or train breaks 76 percent, and driving becomes less appealing (light blue).
Jaffe continues. "So far, no surprises." Actually, that was a surprise for me - transit at 76 percent! Then again, these observations made "in the city core and the inner suburbs" of the D.C. region. "But take a look what happens when a company gives employees both free parking and transit perks:"
(W)e find the probability of driving alone to work in this scenario increased relative to nothing—reaching roughly 83 percent, compared to 16 percent for transit (below, dark blue).
I.e., transit usage dropped 6 percent while drive alone increased 7 percent over the "no benefit" scenario, meaning that no benefits for all is preferable to benefits for all when it comes to increasing alternatives to driving alone.
Jaffe's conclusion: "In the end, what the data give us is yet another example of how incentives to ride transit aren't enough to shift commuter preferences on their own. If cities want real change, they need to create disincentives to drive or park, too."