A Widely Used Planning Manual Tends to Recommend Building Far More Roads Than Necessary

Some of the most trusted planning tools used to manage vehicular traffic have shown themselves to be pretty harmful to city life in certain ways. A metric known as Level of Service, which aims to minimize automobile delay at an intersection, can act as a huge obstacle to public transportation projects. A design book calling for 12-foot lanes, an engineering staple across the country, can speed up car flows and endanger public safety as a result.

It might be time to add one more established tool to the questionable list: the Trip Generation Manual from the Institute for Transportation Engineers, a common guide that tells traffic planners how many car trips will be generated by a new commercial or residential development project.