Low Emissions Zones concept can potentially reduce emissions by 15-18 percent.

Analysis and modeling effort conducted to simulate the potential impacts of a Low Emissions Zone (LEZ) strategy.

Date Posted

Low Emissions Zones Operational Scenario Modeling Report

Summary Information

Under the Low Emissions Zone (LEZ) concept, special measures are implemented for a designated area within a metropolitan region to help deter the access of high-polluting vehicles and reduce the energy and emissions footprint of travel associated with the area.The Low Emissions Zone operational scenario defined by the Applications for the Environment: Real-Time Information Synthesis (AERIS) Program supports the operation of a LEZ that is responsive to real-time traffic and environmental conditions, facilitated by connected vehicle technology and in-vehicle alerts. Within the LEZ modeling effort undertaken in this project, the effects of incentive based policies where travelers receive a benefit for using low emission vehicles in the context of travel to the designated LEZ are simulated.


Modeling was performed using a regional-scale model of the MAG (Maricopa Area Governments) region in Phoenix, Arizona, an area chosen for its dense retail and residential activity. The LEZ area encompassed about 4.4 percent of all zones. The LEZs created targeted emissions reductions through the use of a monetary incentive to motivate a higher market penetration and use of eco-friendly vehicles (HEV, PHEV, EV) in the context of travel to and from the LEZ areas. The LEZs were tested both with and without an additional enhanced transit (ET) component; this enhanced transit component provided travelers who chose not to use or buy an eco-vehicle an incentive through mode-shift.

An integrated travel model system was used that coupled the openAMOS activity-based microsimulation travel demand model with the DTALite dynamic traffic assignment model to simulate the behavioral changes that the introduction of LEZ scenarios brought about. Maricopa Area Governments (MAG) provided network files, travel data, traffic volume data, and travel time and cost matrices by time of day period. These files served as the foundation for building the microsimulation model systems of dynamic travel demand and route choice in response to LEZ scenarios.

The scenarios modeled in this study can be described as follows:
  • Travelers were offered an incentive equivalent to a monetary benefit on a per-trip basis. The incentive values considered included $0.50 or $1.50 per trip (low and high incentive level).
  • The incentive was provided only when a traveler entered the LEZ using a low-emission vehicle; no incentive was offered for travelers exiting the zone.
  • The monetary incentive was tested both with and without enhanced transit service for the LEZs. Service to and from the LEZs under enhanced transit doubled the frequency of transit and reduced the fare by 50-percent.
  • Results were then compared against a baseline scenario that assumed an incentive equal to zero.
Key Findings
  • LEZs: When ET service was available, the energy and emissions reductions for the LEZs were found to be in the range of 15 percent to 18 percent.
  • Entire Region (including LEZs and regular zones): Energy and emissions reductions of 2 percent to 5 percent were realized. The lower end was achieved in the absence of ET service, while the higher end was achieved in the presence of ET service for the LEZs.
Deployment Locations