Road space rationing in Beijing was introduced in the city in a permanent basis after successful results obtained with the policy during the 2008 Summer Olympics. Road space rationing or driving restriction is a transportation demand management regulation aimed to reduce traffic by restricting automobile travel through means such as restriction of cars that could enter common road space based upon the last digits of the license number on certain established days during certain periods in Beijing. The main objective of this restraint policy in Beijing is to reduce the amount of exhaust gas generated by motor vehicles.
Also as part of the smog alert system put in place in the city in 2013, once a red alert is issued, a temporary driving restriction is imposed for the duration of the severe pollution event to reduce the city's cars on the streets by half. Temporary restrictions have been implemented in Beijing twice in December 2015, and one more time in December 2016.
Many road space rationing regulations, such as the even-odd license plate policy, yellow label car policy, end-number policy and passenger car purchase policy have been established in Beijing since the 2008 Summer Olympics. These policies are enforced by traffic enforcement cameras that are able to recognize license plates of automobiles and the police, where the cameras and policemen could recognize license plates of cars that should not be on the road during a certain day, and when found out, the driver of the car would receive certain penalties. Although there have been a significant improvement in the air quality of Beijing and the road space availability, many negative responses of the city's car owners were received.