Table 3.25 Elements of a Public Transportation Network

summary of the most common types of mobility infrastructure by function and characteristics.

Balancing transportation investments is important because it infl uences current and future mode shares and the sustainability of the system. For example, providing free or ample parking for private vehicles may severely reduce the viability of public transportation. Moreover, maintaining or increasing the mode share of public transportation and nonmotorized modes becomes more diffi cult as the fl eet and the infrastructure for private vehicles grows. In addition, new infrastructure, particularly for private vehicles, may induce a rebound eff ect (that is, new demand because of greater capacity).

Public transportation is a particularly important type of mobility intervention in the urban context. Table 3.25 summarizes the main elements of a public transportation network by function, capacity, and characteristics. At a basic level, most elements are applied, but not in a coordinated or balanced way. Best practice recommends creating an integrated network that is scaled to demand. Because the full cost of private vehicle travel is not internalized in most cities, individual decisions to use a private vehicle instead of public transportation may be based on inaccurate costs. To be successful, public transportation systems require specifi c land development patterns. Some corridors are more well suited for rapid transit, including rail, metro, or BRT systems. At the least, cities need suffi cient available or redevelopable land around potential stations and good pedestrian and bus access.

Intelligent transportation systems aim to increase the capacity or effi ciency of infrastructure by harnessing appropriate technology. These systems have the potential to improve highway operations by mitigating congestion, managing speeds, and smoothing traffi c fl ows. Specifi c

Table 3.25 Elements of a Public Transportation Network

SERVICE TYPES FUNCTION CAPACITY CONDITIONS REQUIREMENTS Feeder or circulators Shortest trips (usually Low: small buses Lowest population density, Local streets, low costs (collectors and 1–3 km) within district (7–20 m in length, but with defi ned nodes distributors) or neighborhood 20–40 passengers) Local (bus) Medium trips (3–8 km) Intermediate Medium-density nodes Arterial roads, bus stops, from district to city or schedules: if more than or corridors and other facilities district to district 1 minute headways Commuter express bus Long trips (>20 km) Intermediate Few origins, limited Highways or arterials, bus or suburban rail from regional suburbs destinations stops, and other facilities to city center or district Surface mass transit— All trips from district to Intermediate to high: High population density: Exclusive lanes on major BRT or light rail transit city (usually 5–20 km) ridership of 100,000– 5,000–10,000 persons arterials; 10–20 m of 300,000 daily, 10,000– per km2 right-of-way; stations and 30,000 in peak hour terminals; intermediate investment, typically US$1 million to US$10 million per km, depending on infrastructure Grade-separated mass All trips from district High: ridership of Highest population Underground or elevated transit (elevated or to city (usually 5–20 km) 200,000–500,000 daily, density: >15,000 persons stations and terminals; underground) 20,000–50,000 in peak per km2 highest investment, hour typically US$50 million– US$200 million, depending on infrastructure Intercity (bus or rail) Longest trips from Medium to high Limited origins and Intermodal stations and region to region destinations terminals

Source: Author compilation and estimates (Georges Darido); adapted from PPIAF and World Bank (2008). Note: km = kilometer; km2 = square kilometer; m = meter.