That is by design. Bellevue, a fast-growing city just east of Seattle, uses a system that is gaining popularity around the US: intersection (十字路口) signals that can adjust in real time to traffic conditions. These lights, known as adaptive signals, have led to significant declines in both the trouble and cost of travels between work and home.

In Bellevue, the switch to adaptive signals has been a lesson in the value of welcoming new approaches. In the past, there was often an automatic reaction to increased traffic: just widen the roads, says Mark Poch, the Bellevue Transportation Department’s traffic engineering manager. Now he hopes that other cities will consider making their streets run smarter instead of just making them bigger.

What can we learn from Bellevue's success?

A．It is rewarding to try new things.

B．The old methods still work today.

C．It pavs to put theory into practice

D．The simplest way is the best way.