May 1, 2008Second Chance for Induced Demand?
Author: Ian Sacs
Every workday morning, I step out of the PATH station and walk across 9th Street towards 5th Avenue. As I approach the driver’s side of the cars that are always lined up at the light, I habitually peer down the queue to look for bicycles zipping along the bike lane. I’ve done this for several years now, and during that time, the number of bicycles using 9th Street hasn’t changed much. Over the past few months however, I’ve observed many more bicycles on 9th Street. I suspect this has much to do with the recent pavement striping that demarcates five feet of the street width as a bike lane. Isn’t it funny how a simple stripe down the road could make bicycles seemingly appear from nowhere?
In geeky transportation engineering parlance this phenomenon could be called induced demand. A slightly less cumbersome way to describe this is “If you build it, they will come”. The traditional example of induced demand is the widening of a congested highway. Build some new lanes, take away the construction barriers, et voila, everyone’s new favorite road. New lanes equal comfortable, freely flowing cars and, undoubtedly, carpoolers’ discussion topics are variations on praise for the crafty engineers. So the word spreads about how nice things are on the widened highway, and not only do existing commuters change their routes from nearby roads, but others decide to live a few more miles down the highway from their workplaces, since living is cheaper there and the drive is so convenient. This is how we get to the term induced demand.
Eventually, and sometimes in as short a time as one year, more cars find their way to the widened highway, congestion gets to intolerable, and after years of suffering some engineer proposes widening the highway again. It’s a story repeatedly played out in metropolitan areas throughout the United States over the past sixty years. Subsequently, induced demand has acquired a somewhat negative connotation. But the increase in bicycles in newly striped bike lanes, along 9th Street for example, suggests that induced demand may get a new use to describe something good.
The question is: Does the phenomenon of induced demand apply across modes? It’s easy to see how a new lane on a highway could result in new car trips, since people are already in their cars going somewhere. But will new lane space, previously used by cars and reallocated exclusively to bicycles, get people out of their cars, or taxis, or buses, or subways, and onto a bicycle? We should hope that the answer is yes, but there are conditions. First, we should be realistic that there are just so many people out there willing to regularly ride a bicycle, but I suspect this is a lot more than one might guess. Many cities throughout the world are full of people that Americans are surprised to see commuting on bicycles (think business suits or freezing winter climates). Second, people need reassurances that bicycling on New York City streets is safe. This requires not only time to develop statistics that accurately reflect rider incidents on the expanding bike lane network, but also enforcement of critical riding aspects, such as keeping cars out of bike lanes and ensuring riders wear protective equipment. Third, the image of bicycling in the city has to advance beyond the current misconceptions and stereotypes found in the first two points. This image can be accelerated by focused media campaigns demonstrating how easy and safe bicycling can be.
We’ll have to wait and see if new bike lanes induce new riders. The first anecdotal observations seem to indicate that this is the case. If so, then we may be able to confidently argue that induced demand is, with certain conditions, independent of mode. That would truly be an exciting, and certainly rosier, second chance for an embattled term. |
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