There is a popular belief that the construction of new roads, especially in urban areas, creates more problems than it solves. It is observed that new roads often fill up rapidly and may do little or nothing to improve travel speeds in the long run. Moreover, the increase in motor vehicle traffic often worsens air quality, increases greenhouse gas emissions, increases transport noise, and reduces residential and pedestrian amenity. The objective of this chapter is therefore to describe how to evaluate and model induced traffic in the presence of new road infrastructure. The chapter starts by defining the various kinds of induced travel along with some empirical findings about induced travel. The authors then describe how induced travel should be evaluated and show how some common evaluation methods can produce erroneous results. The last substantive part of the chapter outlines traffic-modeling methods for producing the appropriate travel data.
Abstract