9-line access access management access point accessibility ADA air quality alignment amenity antiplanner atlanta BART BID bike Blogs boston branded bus branded buses brookings brt bus Bus Rapid Transit BYU capacity car pool cars central link Centrality certification commuter rail condo conformity congestion congestion pricing connections consistency coverage crossings CRT cycling DART dedicated dedicated right of way density denver depreciation developers development dynamic pricing economics efficiency Envision Utah equity eugene exclusive extension FAQ favela Federal Funding Flex Bus florida free fare zone freeways Frequent Transit Network frontrunner frontunner Gallivan garden cities gas prices geotagging goat Google grade-separation Granary District growth headway heavy rail hedonic High Speed Rail history housing housing affordability housing bubble housing prices HOV income infill innovative intersections intensity ITS junk science LA land use LEED legacy city light rail linear park location LRT lyft M/ART malls mapping maps market urbanism metrics metro MetroRail missoula mixed mixed traffic mixed-traffic mobile mode choice Mode Share multi-family MXD neighborhood networks news NIMBY office online op-ed open letter Operations parking parking meters peak travel pedestrian environment phasing Photomorphing planning Portland property property values Provo proximity quality_transit rail railvolution rant rapid rapid transit RDA real estate redevelopment reliability research retail Ridership ridesharing right of way roadway network ROW salt lake city san diego schedule schedule span seattle separated shuttle silver line single family SLC SLC transit master plan slums smartphone snow sprawl standing stop spacing streetcar streetscape streetscaping subdivision subsidy Sugarhouse Sugarhouse Streetcar Tacoma taxi technology tenure termini time-separation TOD townhouse traffic signal tram transit transit networks transit oriented development Transit Planning transponder transportation travel time TRAX trip planning trolley tunnel uber university of utah urban design urban economics urban land UTA UTA 2 Go Trip Planner utah Utah County Utah Transit Authority vmt walking distance web welfare transit Westside Connector WFRC wheelchairs zoning

Friday, February 27, 2015

What is Light Rail Transit?

Almost all transit built in the United States since 1980 has been ‘light rail transit’ (LRT)--but ‘light rail’ is a regulatory classification for a vehicle, not a type of transit. The term ‘light rail transit’ covers a wide range of types of propulsion, guideway, and operating characteristics. A clearer articulation of the characteristics of different light rail systems would help to better determine the relationship between transit investment and associated outcomes.

The US is slowly emerging from a transit Dark Age. The combination of subsidized competition and public dis-investment effectively expurgated most urban passenger rail systems from existence. It is necessary to re-invent, or rediscover, the constitutive elements of effect transit systems. Historically, there have been many different types of rail transit systems, but they fall into a small number of distinct types, which might be called suburban railways, street railways, rapid transit systems, and tram-trains.

Suburban railways link major cities to suburban locations distant from the central city. They linked independent towns to a nearby major city. Suburban railways are characterized by high speeds and a very limited number of stops, and characteristically bypassed the outer edges of an urbanized area to reach a central location. The require exclusive guide-way, but their relatively infrequent operation (hourly) means that this requirement can be met through temporary physical separation (crossing gates) rather than the full cost of grade separation.

Street railways develop from the horse-cart service. Initially steam powered, the nuisance presented by the smoke and cinders meant that almost all systems were eventually electrified. Acting more as labor-saving devices, they acted as a ‘pedestrian extender’, rarely traveling much faster than a running man, and stopping frequently. In Europe, the modern implementation is known as a ‘Tram’; in America, as a ‘Streetcar’.

Rapid Transit systems represent yielding to necessity. In locations where cost or difficulty of obtaining sufficient surface right of way (viz: London, NYC, Chicago) underground or elevated construction was necessary. Full grade eliminates the need for sudden stops, making much higher speeds possible. The lack of cross-traffic also makes much higher headways possible, so that it is possible to run a very large number of trains on the same section of track. A bare handful of metropolitan areas have been able to fund the construction of new rapid transit corridors.

Tram-trains operate as railways outside of cities, but as street railways within them. Adapted from the ‘City-Rail’ system in Karlsruhe, Germany, it represents the revival of a historical form of American transit, the ‘Inter-urban’. Inter-urban’s were passenger rail lines running along freight railway right of way between cities, but on city streets within the city. They represent an effort to reduce the friction of transportation, by obviating the need for a mode-switch from train to tram at the edge of the dense, pedestrian oriented central core.

Every implementation of mass transit system represents a trade-off between cost, speed, and access. Evidence suggests that the trade-offs are not entirely granular, but rather represent a series of ‘market niches’ or functional classes of transit. The same classes of transit emerge independently, repeatedly, in different locations, at different times. Analyzing the characteristics of light rail determines that there are ‘functional classes’ of LRT, with different service characteristics, which resemble the service characteristics of historic transit modes.