TOD Versus TAD: The Great Debate Resolved…(?)

Abstract

This paper discusses the distinction between transit-oriented development (TOD) and so-called ‘transit-adjacent development’ (TAD)—a label sometimes applied to less-successful TOD efforts. It is suggested that transport performance is the key factor distinguishing between the two outcomes—and that despite complexities, clearer quantitative benchmarks are needed. Much of the literature and discussion on TOD centres around a perceived failing of many TOD project attempts to deliver a ‘genuine transit-oriented outcome’. Often, this discussion has remained at a thematic level, or has rested on subjective qualitative appraisal, or critique of design or built-form outcomes. With a few exceptions, researchers and experts have generally been reluctant to provide a clear benchmark for TOD success or failure—perhaps because so many well-intentioned TOD efforts fall short of initial expectations. This paper puts forward a proposal that mode share should be the apex metric for determining TOD project success or failure. It is suggested that a majority (50%+) of travel movements need to be accommodated by the sustainable modes (walking, cycling, and public transit) for a location to assume the label of ‘genuine TOD’. Equally, other locations that attempt TOD, but do not deliver a sustainable travel majority, might be placed in the ‘TAD’ category. Benchmark figures from international precincts and locales are used to sustain this argument—with reference to the broader planning, urban development, and design contexts in which these ideas sit.

Notes

1. Figure courtesy BART staff.