[6] He and his firm have completed transit redesign projects in dozens of cities throughout the world, including Houston, Moscow, Auckland, and Dublin.
[15] In December 2017, Walker attracted media attention after publicly feuding with billionaire and Tesla CEO Elon Musk.
Musk expressed his disdain for public transit and reiterated his preference for individual transportation in response to a conference audience question.
[16] Walker criticized him on Twitter, stating that "Musk's hatred of sharing space with strangers is a luxury (or pathology) that only the rich can afford.
[22] Walker frames discussions about public transportation in terms of an area's geometry and how it influences a transit network's ridership and coverage (also known as the "ridership-coverage trade-off").
[26] Walker has argued that transit agencies' focus on predictions and new technologies distracts from necessary improvements to existing transportation systems.
[41] His firm analyzes service change proposals not by predicting ridership — which Walker argues is unpredictable[42] — but instead by measuring how a plan expands or reduces where a person could get to in an amount of time they are likely to have in their day.
[46][47][48] In addition, libertarian Randal O'Toole, a noted transit skeptic, has been a vocal critic of the implications of Jarrett Walker's work.