A sign reminds drivers to choose alternate routes on the first day of the new traffic control measures in Tianjin, north China, March 1, 2014. Local authorities order the removal of one-fifth of vehicles from roads based on the last digit of the license plate on working days and forbid trucks to run within the outer ring area from 7 am to 7 pm from March 1. (Xinhua/Zhang Chenlin)

A traffic policeman introduces alternate routes to a truck driver on the first day of the new traffic control measures in Tianjin, north China, March 1, 2014. Local authorities order the removal of one-fifth of vehicles from roads based on the last digit of the license plate on working days and forbid trucks to run within the outer ring area from 7 am to 7 pm from March 1. (Xinhua/Zhang Chenlin)

Two trucks leave the highway before entering the outer ring area on the first day of the new traffic control measures in Tianjin, north China, March 1, 2014. Local authorities order the removal of one-fifth of vehicles from roads based on the last digit of the license plate on working days and forbid trucks to run within the outer ring area from 7 am to 7 pm from March 1. (Xinhua/Zhang Chenlin)

A traffic policeman introduces alternate routes to a truck driver on the first day of the new traffic control measures in Tianjin, north China, March 1, 2014. Local authorities order the removal of one-fifth of vehicles from roads based on the last digit of the license plate on working days and forbid trucks to run within the outer ring area from 7 am to 7 pm from March 1. (Xinhua/Zhang Chenlin)