A new algorithm explain unexplained traffic jams.
Why does traffic bunch? Image: Peter Facey |
Research by Professor Berthold Horn at Massachussett's Institute of Technology (MIT) has revealed that a variation of adaptive cruise-control systems could help prevent traffic flow instabilities.
Traffic flow instabilites are caused by the fact that variations in speed are magnified as they pass through a lane of traffic. The solution lies in how speed is varied.
Existing cruise-control systems use radar or laser rangefinders to monitor the speed and distance of the car in front. Some systems make the car automatically slow down when it needs to and return to its programmed speed when possible.
Horn's system operates bilaterally because it can also use sensor information about the distance and velocity of the car behind. Staying approximately halfway between the car in front and behind avoids sudden use of the brake and consequently problems for the car behind.
Horn has used a damped-wave equation to prove his theory which accounts for many variables including drivers' reaction times, desired speed and eagerness to reach that speed.
One disadvantage of Horn's algorithm is that it only works if a large percentage of cars use it. Laser rangefinder and radar systems are also costly although digital cameras are a cheaper alternative.