Transit and Retail (and TOD-ness)

 (You should cite my article about it). I've reproduced some relevant bits from a pre-submit draft below. 

Abstract

Central to the concept of Transit Oriented Development (TOD) is a retail core situated around stations. However, successful retail near light rail transit stations has been elusive. Despite significant implications for land use, transportation, and economic development planning, little research exists to explain the gap between TOD concept and reality. This research moves conversation away from an assumption that transit stations and retail naturally co-exist and toward an understanding where intentional station area design choices demonstrated to drive retail employment. 

Introduction

Transit-Oriented Development (TOD) was developed and promulgated as an alternative to urban sprawl. TOD was conceived as a walkable, mixed-use development oriented toward a transit station, providing residential, service, and employment opportunities. Each TOD was expected to have a commercial core containing convenience retail and offices for local services. Larger commercial cores were to contain grocery stores and destination retail. Locating retail within a walkable distance would reduce private vehicle use and encourage sustainability.

Within the land uses planned to comprise the mixed-use core, retail is articulated as an essential component of TOD. Indeed, many successful TOD projects include retail. However, many stations do not, either lacking retail entirely or hosting a lackluster or struggling retail area . In fact, research shows station development is weakly at best (and not uniformly positively) associated with retail development in California. Given the popularity of TOD as a strategy for land use planning and development near light rail stations and the theoretical weight given to TOD’s retail component, research should work to understand the factors that challenge and enable retail success. Yet, the literature doing so is scant and not recent. Lacking this understanding, the areas near transit stations may merely develop as Transit-Adjacent Development (TAD), TOD’s evil twin, which are substantially more auto-dependent.

Previous Research

What is TOD?

A model TOD consists of a walkable mixed-use core surrounded by apartments, surrounded by townhomes. The density translates to a market for commercial development providing daily goods and services. The central transit station provides accessibility to employment, making the location desirable. In practice, the term TOD has become a metonym for the area within a half mile buffer of a station. Development promoted as TOD takes on many forms, sometimes not closely resembling a theoretical TOD. Of defining TOD, the variability in practice parallels disagreement in the literature that evolved over the decades following the original vision of the concept. By 2002 there were enough definitions that the term had become subjective, and that TOD success is context-specific and may not be generalizable at all. There is a a striking lack of agreement regarding what constitutes TOD--many studies of TODs make an effort to classify TODs, but do so “based on subjective criteria of the context in which they are built”, and/or are context-specific or dependent on local data. While these efforts enable case study analysis, they do not move the field toward systematic or generalizable understandings of the interactions of transportation and urban development processes.

In 2009, Renne utilized a case study approach to articulate and demonstrate that metrics of key urban design-related features—density, design, and diversity—relate strongly to qualitative distinctions between TOD and TAD. Renne states that “TOD describes a station-area precinct that is compact, mixed-use, and facilitates transit connectivity through urban design,” and that a TAD is not functionally related to the transit infrastructure in terms of land use or design. A TAD is distinguished by (among other things) low density, pervasive single-family housing, industrial land uses, and surface parking.

Shortly thereafter, CTOD released the Performance-Based Transit-Oriented Development Typology Guidebook. While acknowledging that the report moved the field away from the contested definitions and toward a framework, it is one that is “somewhat cumbersome and mainly a one-dimensional analysis”, and to to build on and improve CTOD’s work, a point-based system identifying a “minimum benchmark definition” of TOD, was derived, such that a station area receives 1 point for each of the following criteria:

1)     - Greater than 30 jobs or residents per gross acre

2)     -Not having 100% of land uses as either residential or commercial

3)    - Average block size less than 6.5 acres

In this system, a score of 0-1 indicates a station area is a TAD; a score of 2 reflects a hybrid station area; and a score of 3 suggests a TOD, such that station areas’ TOD Index scores (and its subcomponents) are positively associated with retail employment. A reasonable counter-argument to this hypothesis is that in the suburban context new retail development implies substantial surface parking, to the exclusion of other land uses, resulting in zero scores for the density and urban design criteria above. However, theoretically, a fixed guideway transit station improves accessibility, thus raising land values and thereby enabling both structured parking and additional land uses. Further, where structured parking is not dominant, the decreased density of activity caused by large surface parking lots necessarily reduces the quantity of retail within the station area buffer, compared to retail that might develop within a TOD.

Transit and Retail.

Early research on retail near transit stations relied on analyzing land uses and land use changes near transit stations. Due to difficulty obtaining data, many studies were limited to a few stations. For example, Renne (2009) includes only three stations. More recent scholarship shifts to employment or business openings as the outcome variable, but much of this research is inconclusive regarding retail. Research suggest a relationship between Bus Rapid Transit and employment by industry, findings on retail were not statistically significant. Opening the Phoenix light rail resulted in a 28% increase in retail business openings within a mile of the transit line, but that substantial coincident redevelopment undermines establishing causality. Transit stations in California tend to be in locations with high shares of retail employment but there is no relationship between station development and resulting retail development.