The document discusses the engineering challenges of developing sustainable transport infrastructure for cities. It outlines six key building blocks needed: 1) a citywide plan created by politicians through policy and vision, 2) design planning by traffic planners, 3) urban planning by city planners, 4) highway design by road engineers, 5) traffic orders by traffic engineers, and 6) graphic design by communication experts. The document emphasizes the need for policies and infrastructure that prioritize walking, cycling, and public transit to address issues of emissions, public health, air quality, and climate change.