Climate and air quality impacts of off-peak commercial deliveries

This study evaluates the potential impacts of off-peak delivery (OPD) for greenhouse gases and air pollutant emissions, with an application to the Greater Toronto Area. Multiple scenarios are formulated. OPD improves network congestion and travel times but increases vehicle kilometers travelled (VKT). The increase in VKT is attributed to road freight vehicles modifying their routing during the off-peak to longer routes. VKT generation is also attributed to induced passenger travel demand generated in response to improvements in traffic conditions during the daytime. Induced VKT plays an important role in limiting the reductions in greenhouse gases and nitrogen oxide emissions attributable to OPD. Yet, OPD scenarios reduce the emissions of fine particulate matter for both passenger and freight vehicles by reducing congestion. While total daily emissions either decrease or change minimally, the spatio-temporal distribution of emissions indicates increases in night-time emissions, particularly in communities located around highways and major arterial roads.