National Academies Press: OpenBook

Reinventing the Urban Interstate: A New Paradigm for Multimodal Corridors (2011)

Chapter: Appendix E - Glossary of Terms

« Previous: Appendix D - Existing Multimodal Corridor Case Studies
Page 146
Suggested Citation:"Appendix E - Glossary of Terms." National Academies of Sciences, Engineering, and Medicine. 2011. Reinventing the Urban Interstate: A New Paradigm for Multimodal Corridors. Washington, DC: The National Academies Press. doi: 10.17226/14579.
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Suggested Citation:"Appendix E - Glossary of Terms." National Academies of Sciences, Engineering, and Medicine. 2011. Reinventing the Urban Interstate: A New Paradigm for Multimodal Corridors. Washington, DC: The National Academies Press. doi: 10.17226/14579.
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Page 147
Page 148
Suggested Citation:"Appendix E - Glossary of Terms." National Academies of Sciences, Engineering, and Medicine. 2011. Reinventing the Urban Interstate: A New Paradigm for Multimodal Corridors. Washington, DC: The National Academies Press. doi: 10.17226/14579.
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Page 148

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146 Multimodal Facilities: The combination of physical facil- ities for highways, public transit, pedestrians and bicycles. (Multimodal Facilities = Highways + Transit + Pedestrians + Bicycles). Corridor: The combination of multimodal facilities and the land uses surrounding them. (Corridor = Multimodal Facilities + Surrounding Land Uses). The interaction of multi- modal facilities and land uses can take many forms, but can generally be described as ranging from auto-oriented to transit- oriented corridors. These two polarities are described in greater detail below. Multimodal Corridor “New Paradigm”: Optimized com- binations of multimodal facilities and land uses. Physical Context: Refers to the characteristics of the land use, urban design (street and block characteristics), social, economic, demographic, and so on surrounding the existing or future transportation facilities. Institutional Context: Refers to the institutional arrange- ments for physical design, highway operations, other modal operations, and land development decisions along and near the corridor. This also includes institutional arrangements for pro- viding access to the corridor from the area served by the corri- dor as well as the policies, regulations, and other transportation management actions that help determine corridor operations. Intermodal Facilities/Station: A station or node where transfers between travel modes are facilitated. System Access: Refers to the characteristics of how the trans- portation facility is accessed, including transit stations, bus stops, on- and off-ramps-and so on Central Business District (CBD): The CBD is the central district of a city, usually typified by a concentration of retail and commercial buildings.1 Transit Mode Terminology: • Local Bus: The most common form of public transit in the United States, it is distinguished by single bus vehicles op- erating with a capacity of 35 to 50 seated passengers, oper- ated along fixed routes, running in mixed-flow traffic along surface streets. Since they run in mixed traffic, buses are typ- ically slower than other forms of transit, and because they follow fixed routes with frequent stops, they typically travel at slower speeds than auto traffic in the same corridor. • Express/Rapid Bus: Generally distinguished from local bus service by the limited number of stops made along a fixed route. The route can be in a surface street in mixed-flow traffic lanes either on a local surface street or a freeway. Fewer stops mean fewer opportunities to attract passen- gers, so this mode is best suited to serve a large destination such as a central business district paired with either a sys- tem of widely spaced intermodal transfer stations (for ex- ample, park-and-ride lots surrounding stations) or dense residential clusters. Also called rapid or transit-priority buses, express buses can be fitted with signal priority tech- nology to increase running speeds. Other route improve- ments include queue jump lanes, bus stop “bulb-outs,” and exclusive bus lanes. These improvements are also associ- ated with BRT (see description below), but unless most or all of these elements are in place and in use, the route is gen- erally considered express or rapid bus, not a full BRT sys- tem. Express bus service with park-and-ride lots around their stations can serve at relatively low corridor residential densities of four dwelling units per acre and CBDs as small as 20 million square feet because this configuration draws on a large commuter shed. Pedestrian access stations re- quire higher corridor residential densities of 15 dwelling units per acre or more and a CBD of at least 50 million square feet.2 Express buses are also very flexible. An express A P P E N D I X E Glossary of Terms 1http://en.wikipedia.org/wiki/Central_business_district 2Pushkarev, B. & J. Zupan, Public Transportation and Land Use Policy. Indiana University Press, Bloomington, IN, 1977. p. 187.

147 bus—such as AC Transit’s Transbay routes from the East Bay to downtown San Francisco—can run as a local service in a collector mode, then as an express bus to the destination. • Bus Rapid Transit (BRT): The most important feature of BRT is that it runs on a dedicated, exclusive lane of travel, giving it a high level of service reliability (since it does not compete for right-of-way with other modes) and speed. Bus priority technologies (such as signal prioritization) are often used to improve travel times and provide a competi- tive edge to BRT vis-à-vis other modes. Off-bus fare collec- tions as well as platform boarding and alighting are fre- quently used to reduce dwell times at stops.2 In addition to operational improvements, the cost of a BRT system can be about one-third that of a light rail system.3 This makes BRT feasible for somewhat less dense and smaller CBD corridors than more capital-intensive rail systems. As a rule of thumb, minimum CBD size for a BRT system to generate adequate ridership is around 25 million square feet.4 • Light Rail Transit (LRT): Light rail vehicles run singly or in short trains on tracks in a variety of right-of-way environ- ments, including mixed-flow surface streets, dedicated lanes with grade crossings, and fully grade-separated dedi- cated facilities.2 Compared to BRT, LRT offers and requires more fixed capital investments and, as such, is thought to be more attractive to riders and developers.5 Another ad- vantage of LRT, particularly in comparison to heavy or commuter rail, is its operating flexibility. LRT can operate in mixed traffic and exclusive rights-of-way conditions, all along the same line.2 This is important because many free- way right-of-ways do not penetrate downtown areas, and LRT can do so on city streets at a relatively low cost com- pared to heavy or commuter rail (see below).6 Therefore, for multimodal corridors where transit is being retrofitted into an existing freeway right-of-way, the freeway need not run directly to the activity center that the transit system will serve. Rather, the LRT system can take advantage of the op- portunities for colocating its tracks along an available free- way right-of-way for most of the route, then veer away to run on surface streets to reach the CBD. Minimum CBD size for an LRT system is around 35 million square feet, but for lines that can be built along existing rights-of-way (such as a freeway), CBDs as small as 20 million square feet may be financially feasible. Minimum corridor residential den- sities for LRT range from 9 to 12 dwelling units per acre.2 • Heavy Rail/Rapid Transit (HRT): Heavy rail transit pro- vides intraurban service running on exclusive, dedicated, fully grade-separated rights-of-way. Called “heavy” because of its large passenger capacity, HRT can generally carry up to 400 passengers per track per hour at high speeds and excellent service reliability. Cars are generally designed to carry 90 to 150 people each in comfort, and up to double that in “crush load” conditions. The trains are typically very long compared to LRT, up to 8 to 11 cars depending on their size. To reduce dwell times and increase service speeds, HRT systems have fare collections in the stations, as well as high-level station platforms and more doors per car than other vehicles to speed boarding and alighting.2 Express HRT service is sometimes provided via additional, parallel tracks to allow skip-stop trains.7 HRT is generally thought to be financially infeasible for corridors with CBDs less than 50 million square feet and corridor residential densities less than 12 dwelling units per acre.2 • Commuter Rail: Commuter rail provides service between a metropolitan area’s suburban areas and its main CBD. It usually shares tracks with other railroad traffic (freight and intercity passenger) and so can suffer from delays due to these competing uses. Usually, its power source is on-vehicle (locomotive) versus off-track (for example, overhead wires and middle third rail). Commuter rail almost always runs at grade since locomotives are too heavy for aerial or subways, and they typically have stub-end stations at the periphery of downtowns. Suburban stations almost always have surface parking. Typically, commuter trains run less frequently than other forms of rail transit, often only dur- ing peak periods. In this way, they tend to cater to “choice” riders who prefer public transport because of speed, relia- bility, and avoidance of traffic congestion and parking problems. To compete with auto traffic travel times, com- muter trains are often scheduled to skip stops, resulting in express and local services in the same corridor. Compared to intercity rail service, commuter rail has more frequent stops and seating densities. This requires train equipment with high acceleration and deceleration as well as seating and door configurations that allow rapid loading and un- loading. In these ways, commuter rail equipment and sys- tem design are comparable to HRT or LRT, but the route distances are often longer, ranging between 15 and 30 miles. Because of these design features, there are few commuter 3Leal, Monica T. & Robert L. Bertini, Bus Rapid Transit: An Alternative For De- veloping Countries, http://web.pdx.edu/∼bertini/brt.pdf 4TCRP Report 90, Volume 2, page 2-4. 5Diaz, Roderick B., Impacts Of Rail Transit On Property Values. http://www. apta.com/research/info/briefings/documents/diaz.pdf 6Examples of LRT systems traveling on city streets through central business dis- tricts include Boston, Edmonton, Philadelphia, Pittsburgh and San Jose. 7Examples of HRT systems providing express service include Chicago, New York City, and Philadelphia.

148 rail station area TODs. Where development densities pro- vide an adequate ridership market, commuter lines are electrified and the stations have platforms and automatic doors. Where corridor market densities are lower, slower speeds are acceptable and diesel-pulled trains with low- level station platforms are frequently used.2 Commuter rail is generally thought to be financially infeasible for cor- ridors with CBDs less than 50 million square feet. The CBD should have a pre-existing rail line serving it, and the service corridor residential densities should be no less than 1 to 2 dwelling units per acre2 with good transit and auto feeder access to corridor stations.

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TRB’s Transit Cooperative Research Program (TCRP) Report 145: Reinventing the Urban Interstate: A New Paradigm for Multimodal Corridors presents strategies for planning, designing, building, and operating multimodal corridors—freeways and high-capacity transit lines running parallel in the same travel corridors.

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