TDM, when employed, works. TDM agencies around the country use a treasure’s trove of strategies to get people out of cars and onto trains, buses, and bikes, which is something that has to happen if we don’t want our roads to become unusable due to traffic and environmental congestion.
But one major problem with the practice of TDM is that it has had a hard time making the case that it is a cost-effective alternative or at least add-on to big infrastructure projects. It seems pretty obvious that teaching people, educating them, about how to use our systems will make those systems run more smoothly. But there has never been a great way to back up that assumption with hard numbers.