Abstract:

The promotion of electric vehicles （EVs） has become an important way for green development of urban delivery fleets. In recent years， some cities in China have implemented policies for delivery fleet expansion and renewal， which include without vehicle energy types restriction （referred to as “hybrid policy”） and designated new energy vehicles such as electric vehicles （referred to as “electric policy”）. To study both policies， a hybrid fleet composed of fuel vehicles （FVs） and EVs is analyzed and mathematical programming models for fleet renewal and routing optimization are presented， which consider access restrictions for FVs and the driving range limitation for EVs. On this basis， the social welfare under the hybrid and electric policies is compared. An improved genetic algorithm to solve the proposed optimization models is designed. The solutions are compared with them solved by the Gurobi. Using the customer demand data of company A， it is found that in comparison to the hybrid policy， the electric policy can make the proportion of EVs in the fleet the same or higher， often increase the total EV mileage， and result in higher total fleet costs. When the operating cost of EVs （FVs） decreases （increases）， the total mileage of EVs can rise. In the presence of the higher driving range of EVs or more access restrictions for FVs， the total mileage of EVs does not necessarily increase. The government should push for the electric policy if the used number of EVs under the electric policy is higher （lower） than that under the hybrid policy and the environmental impact of EV production is sufficiently small （large）； Otherwise， the government should not implement the electric policy blindly.

Key words: city distribution, mixed fleet, electric vehicles, fleet planning, renewal policies