Traffic management in an era of near-perfect information


When I wore a younger man’s clothes (thank you Billy Joel) I drove a taxi cab in New York City. The hours of driving, shuttling people from places familiar and obscure, gave me an intimate understanding of the city’s streets. In my mind was a one-of-a-kind map, filled with detailed directions, shortcuts and escape routes. And, among the cadre of cab drivers, everyone boasted they knew the best shortcuts. It was more than just braggadocio: getting your fares there faster meant picking up a few more rides in the day and earning more than a few extra bucks by the end of it. The driver’s credo: pick up your fare, get rid of him as fast as possible, and start all over again.

When I later attended graduate school for traffic engineering, I remember being intrigued learning about John Wardrop’s theory of traffic equilibrium: travel times on routes used are all equal, and travel times on routes used are shorter than routes unused. In Wardrop’s world there were no shortcuts. This flew in the face of what I knew from the streets; surely, my experience made me more clever than the average driver. So, in the early 1990s I authored a book called New York Shortcuts and Traffic Tips, to help make driving in New York City easier. But, I realized that it could become a victim of its own success: if it became a bestseller and everyone took the shortcuts, they would fill up with traffic and wouldn’t be shortcuts anymore.

Wardrop’s theory was based on perfect information, and shortcuts rely on secrecy. We are now upon the era of near-perfect information. The mass adoption of GPS-enabled smartphones has created a huge legion of sensors gathering data. Real-time routing can create a meaningful improvement in traffic performance, diverting drivers and reducing travel times. This coordination can improve daily commutes and isn’t far off the ‘social optimum’ traffic assignment that Wardrop theorized. But real-time routing also means it is open season on detours and cut-through routes via neighborhood streets that were once sought out by only the most wily behind the wheel. In LA, local groups are fuming over a perceived increase in traffic on local streets – which they attribute to way-finding apps – and are trying to convince app makers to change the way they route traffic. Route choices may seem inconsequential when they are made by a few individuals, but when technology enables companies to offer these choices centrally and millions follow the advice, that’s a whole new component of the transportation system that requires thoughtful management.

There’s no doubt in my mind that connected and autonomous vehicles will be part of our future. But how will all these vehicles be routed? What will their objective functions be? Who will decide? As ITS professionals, it is important that we take a step back and evaluate the wider impacts of our innovations. After my book came out, I was called to task by Greenwich Village after people started using a shortcut I had highlighted. Will the ITS community-at-large be called to task and possibly sued because of actions taken based on information they release?

In my next column I will write more about autonomous vehicles and cities; are they incongruous or maybe even superfluous? Stay tuned.

Illustration: Ian Parratt,

For more from our excluisve columnists check out the latest issue of Traffic Technology International here

Share this story:

About Author