Ai Lijun, a traffic police officer in Luohu District dressed in the uniform of a food delivery company, hands a food order to a customer on Dongmen Central Road on Tuesday at noon. Ai had a role exchange with food deliveryman Zhao Chunxiao, who helped direct traffic on the street Tuesday. The exchange was aimed at letting traffic police officers and food deliverymen understand each other’s jobs. Zhao said he would follow traffic rules after the exchange. Liu Yujie