This isn’t a new problem, of course. During the car boom of the 1960s, city planners had one seemingly obvious solution: build more and wider roads. But it didn’t work. The more roads created, the more cars they attracted. In California, for example, a 1997 study found that new, additional traffic will fill up to 90% of any increase in highway capacity within just five years.
While every city – whether London, Beijing or New York – has its unique set of traffic problems, there are a few common issues: many people insist on driving their own car, instead of sharing rides or using a bicycle; up to a third of cars on roads are drivers looking for a place to park; and then there’s the human factor: most of us simply are not very efficient drivers.
So what’s the solution? Some traffic planners are betting on car-pooling lanes, more park-and-ride opportunities, and improved public transport to ease congestion. Several cities have resorted to less subtle methods, like banning cars from driving on certain days, alternating between cars with licence plates that end in, say, even or uneven numbers.
Aggression vs timidity
But understanding what causes congestion in the first place may be the first step. Bottlenecks in the road and the sheer volume of cars are obvious sources. However, some traffic jams appear seemingly spontaneously, maybe caused by the “butterfly effect” of a single driver suddenly switching lanes, which results in cars behind him braking suddenly, with the ripple effect rapidly snarling up the highway.
A study by the Georgia Institute of Technology in Atlantablamed a combination of aggressive drivers – too fast and too close to the car in front – and timid drivers, who leave large gaps in traffic; both kinds force other drivers to brake, resulting in yet more ripples bringing traffic to a standstill.
Scientists have used many analogies to try to model traffic flows, from fluid and gas flow, to the movement of birds and skiers. However, says Gabor Orosz of the University of Michigan, “although such analogies may help scientists to gain some understanding, it is becoming more and more obvious that traffic flows like no other flow in the Newtonian universe”.
As much of this traffic is drivers looking for a place to park, some cities are trying to manage flow with systems that use sensors to determine whether a particular spot on the street, or in a car park, is occupied or vacant. Link these smart sensors with a system that guides drivers quickly and efficiently to vacant parking spots and the hope is this will ease congestion. The first trial of these sensors started in San Francisco, with Los Angeles not far behind, both cities currently being serviced by ACS, a Xerox subsidiary.
Two years ago in Russia, Moscow trialled smart parking providers and is now using a system developed by Worldsensing, says Mischa Dohler, professor at King’s College London and co-founder of the company. He says that with nearly 20,000 smart parking spaces, Moscow is by far the largest smart parking smart city deployment in the world.
The number of traffic jams has gone down, Dohler says, “mainly because people are being informed about the non-availability of parking, and they thus keep out of the narrow one-way streets in the centre.”