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5.10.3 Regional Transportation Network

1. Realize the “Regional Transportation Network is Part of a Redundant Transportation System – Transportation agencies, both public and private, had to work together to provide alternative travel options to the public. But the level of complexity and the alternatives used varied. The solutions depended on the circumstances presented to decision makers. And the solutions shifted over time in response to changes in travel behaviors of the public to the options presented to them.
   
   In the case of New York City, Lower Manhattan has a dense set of redundant transportation infrastructure. The infrastructure consists of a pattern of local streets connected to arterials along the perimeter, a multitude of subway lines, on-street bus service, water ferries, and pedestrian accommodations. Because of that, people have multiple options for getting around on a daily basis.
   
   The Los Angeles highway system in the urban area has a fairly extensive set of redundant arterial and local streets. At the time of the earthquake, the Los Angeles Department of Transportation was implementing a “Smart Corridor” project that had identified parallel arterials as an important option for commuter traffic. This system has the ability to divert freeway traffic onto the arterial streets during times of heavy congestion. Being able to implement this after the earthquake allowed the agencies to minimize some of the traffic congestion that occurred as a result of the closing of the damaged interstate segments.
   
   But to the north, the canyons and valleys restricted the number of alternative roads that are feasible. Because of this officials were presented with fewer options for rerouting traffic and these areas experienced the heaviest traffic backups in the weeks and months after the earthquake.”
   Effects of Catastrophic Events on Transportation System Management and Operations: Cross-Cutting Study

2. Realize the Transit System Can Provide Redundancy – “In addition to roadway redundancy, the transit system helped alleviate some of the initial congestion caused by reconstruction. With an already extensive bus system, the Los Angeles County Metropolitan Transportation Authority increased Metrobus service following the earthquake to respond to the demands of commuters.
   
   In Washington, the highway departments were able to take advantage of reversible lanes to help increase the volume of traffic that could exit the Washington, DC, area that morning. Washington Metropolitan Area Transit Authority had the ability to reroute its subway lines to avoid crossing the Potomac River Bridge. One of the major infrastructure improvements that Washington Metropolitan Area Transit Authority has considered is the construction of a second rail tunnel through the central rail system to provide redundancy in case of problems to the main line.”
   Effects of Catastrophic Events on Transportation System Management and Operations: Cross-Cutting Study

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February 7, 2006
Publication #FHWA–HOP-08-015