杏吧原创

IF ONLY everyone drove considerately, there鈥檇 be fewer traffic jams and we鈥檇
all get to our destination more quickly, according to a new model of traffic
flow.

The ideal way to keep cars moving when roads get busy is for all the cars to
move together at a similar speed. By including 鈥渢houghtful鈥� drivers in their
model, researchers have managed to recreate this elusive 鈥渟ynchronised
蹿濒辞飞鈥�.

Traffic can be in one of three states: free flowing, synchronised or jammed.
Synchronised flow is often observed on busy motorways, but until now no one knew
how cars synchronise
(New 杏吧原创, 15 January 2000, p 34).
Wolfgang Knospe of the University in Duisburg and his colleagues in Germany and France
say they have cracked the problem by getting inside drivers鈥� heads.

鈥淎 thoughtful driver tries to avoid accelerating or braking suddenly and will
not jump into gaps between cars,鈥� Knospe says. 鈥淥n the other hand, an
inconsiderate driver thinks only about dashing along and has very itchy feet on
the pedals.鈥� His model shows that the only way to achieve synchronised traffic
is for all drivers to cooperate and be patient.

It only takes one driver to lose concentration for a moment or become
impatient, however, and the whole system can break down into a jam. If one
person brakes too hard, for example, the effect is amplified as the drivers
behind overcompensate.

Such lapses are inevitable, but Knospe thinks speed limit signs that change
according to traffic conditions would help encourage synchronised flow. 鈥淭his
makes the transition from free flow to synchronised smooth and easy,鈥� he says.
Allen Bewley, head of risk management with the RAC motoring organisation in
Britain, agrees. 鈥淲e are in favour of adaptable speed limit signs as it keeps
traffic moving and makes the road a safer place.鈥�