Tradeoffs between costs and greenhouse gas emissions in the design of urban transit systems
Recent investments in the transit sector to address greenhouse gas emissions have concentrated on purchasing efﬁcient replacement vehicles and inducing mode shift from the private automobile. There has been little focus on the potential of network and operational improvements, such as changes in headways, route spacing, and stop spacing, to reduce transit emissions. Most models of transit system design consider user and agency cost while ignoring emissions and the potential environmental beneﬁt of operational improvements. We use a model to evaluate the user and agency costs as well as greenhouse gas beneﬁt of design and operational improvements to transit systems.