End These 5 Transportation Planning 'Rule of Thumbs'

Joe Cortright argues that planning rules of thumb are "all thumbs," when it comes to relating transportation to land use. " One of the problems with rules of thumb (or the more academic term, 'heuristics')," writes Cortright, "is that while they may work well in many cases, they may work very poorly in others – and they may be subject to important cognitive biases that lead us to make bad decisions."

Two of the five old rules of thumb, as described by Cortright:

• "We should have a high 'level of service' on our streets."
• "We should plan for a certain number of car trips to be generated by every land use, no matter what it is."

As an alternative to the transportation planning status quo, Cortright also recommends four new rules of thumb, including these two examples:

• "Slower is safer."
• "Our objective should be accessibility, not mobility."