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3 CHAPTER 2 Tools, Techniques, and Technology for Suburban Service Development Understanding Regional Activity guidelines that transit operators and policy makers may use Patterns to inform their decisions on where to operate service and what characteristics the service should have, given different The urban form of modern cities and contemporary sub- performance expectations. urbia is increasingly characterized by multiple activity centers. TCRP Report 55 identified six types of suburban land-use The polycentric city is a complex hierarchy of centers, corri- environments based on their diversity of uses and how the dors, and areas in between. Whereas a large share of trips in the intensity of their development (i.e., density) relates to that of pre-automobile city went radially to and from the downtown, the surrounding area. These environments included residen- the modern city is characterized by dispersed travel patterns tial suburbs, balanced mixed-use suburbs, suburban cam- in all directions. This is evidenced by the continuous rise in puses, edge cities, suburban corridors, and exurban corporate suburb-to-suburb travel over the last few decades. enclaves. Thinking back to the discussion of the activity sur- The initial step in designing such a regional transit system face, each topographical feature of the activity surface corre- involves understanding the intrinsically related patterns of sponds to one or more of these suburban environments: development and travel demand. Travel demand is the sum of the individual trip origins and destinations of every traveler in the region. While this information can be represented in Peaks represent the major activity centers, such as down- large trip matrices, as is done in travel demand models, a use- towns, shopping centers, edge cities, and community busi- ful method for visualizing regional development patterns and ness districts. In a polycentric city, peaks have various travel demand is to analyze the activity surface. heights based on their relative share of the region's total As illustrated in Figure 2-1, an urban area can be thought of residential, employment, commercial, medical, and recre- as a surface that represents the relative importance of each ational activity. Edge cities and downtowns of balanced point across the metropolitan region. The relative importance mixed-use suburbs are examples of peaks. Peaks generally of a point is a function of the number of activities that serve have urban characteristics, such as a diversity of uses, as the ends of trips, such as jobs, shopping, medical care, recre- higher densities, and perhaps deterrents to driving. ation, and housing. The activity surface of a pre-automobile Ridges represent the major travel corridors in a region. city was a relatively simple convex surface with a noteworthy These corridors frequently connect peaks and are often peak over the downtown, a single mountain in a large plain. lined with higher-density residential, employment, or com- The modern, polycentric city has a much more complex, mercial uses. Suburban corridors are examples of ridges. bumpy activity surface characterized by peaks of various Ridges have more suburban qualities, such as less diversity heights over the traditional downtown and outlying centers, and large gaps in the street wall, although there may well be ridges connecting peaks along major corridors, and plains in deterrents to driving in the form of traffic congestion. between, where people live in sprawling subdivisions. Points represent places in the region that are destinations Supported by tools such as the activity surface, this project for trips, but that do not necessarily fall on peaks or ridges. explores the relationships between the land-use characteris- Suburban areas are characterized by a relatively high share tics and travel patterns of the service area, the operating char- of destinations that are not located within walking distance acteristics of the service, and the service's performance in a of other major activity centers or on major transportation range of suburban environments. These relationships provide corridors. Suburban campuses and exurban corporate