Even though most people don’t know what transportation demand management is, they’ve probably been affected by it. TDM encompasses any behavioral technique designed to lower the number of people driving alone, from employee transit benefits to real-time transit-arrival information.
The idea came to prominence in the 1970s, when two major oil crises forced Americans to do the unthinkable: drive less. And this truly was unthinkable, at least in 1976 Los Angeles, when Caltrans introduced high-occupancy vehicle (HOV) lanes to the Santa Monica Freeway.
The lanes – called the “Diamond Lanes” at the time – were incredibly unpopular. One of the many unbelievers was Joan Didion, writer extraordinaire. Her criticism has insights for TDM practitioners today.
In her book The White Album, a collection of nonfiction essays reflecting on the late 1960s and early 70s, Didion writes:
The problem seemed to be another Caltrans “demonstration” or “pilot,” a foray into bureaucratic terrorism they were calling “The Diamond Lane” in their promotional literature and “the Project” among themselves. That promotional literature consisted largely of schedules for buses (or “Diamond Lane Expresses”) and invitations to join a car pool via computer (“Commuter Computer”) made clear not only the putative point of the Project, which was to encourage travel by car pool or bus, but also the actual point, which was to eradicate the Southern California illusion, that of individual mobility, without anyone really noticing. This had not exactly worked out.
In one fell swoop, Didion identifies the chief obstacle of any effort to reduce driving: that it eradicates the illusion of individual mobility.
The destruction of this illusion is exactly why the Diamond Lanes were unpopular – so unpopular, in fact, that an unnamed Caltrans official told a reporter in 1994 that they abandoned the name for HOV.
Southern California’s HOV system is now huge, carrying more people than any other HOV system in the country, according to LA Metro. Yet most transportation improvements policymakers and advocates put forward face an uphill battle to mainstream acceptance (the opposition to bike lanes is a great example of this).
In her criticism, Didion provides the solution: TDM practitioners and policymakers need to communicate the goals of what they are doing.
Didion writes, after interviewing Caltrans officials, that the goal of the Diamond Lane was not to reduce traffic congestion on the Santa Monica Freeway, but to increase vehicle capacity – to carry more people on the freeway with fewer vehicles. That seems at odds with TDM today, which is largely focused on keeping traffic flowing by taking cars off the highways.
It’s okay for goals to change, or for TDM policies to aspire to both reduce traffic and increase capacity. But if the goals of any transportation project aren’t clearly communicated and explained, then it will appear to drivers as a destruction of their personal freedom – when in reality, policies intended to reduce driving improve transportation for everyone.