ABSTRACT
Rapid transit projects of various forms (elevated, at grade and subsurlace) and significant length are being pursued in various countries as a way of coping with ever increasing congestion, capacity problems, and environmental concerns. Typically, these projects are constructed in very busy urban corridors. The need to capture economies of scale in order to control costs coupled with the need to localize the impact of the construction process on traffic dictate that such projects be built in an order] y location sequence. Direct benefits of doing so include minimizing the cost of equipment spreads in part through the sharing of key resources, minimizing construction travel time, minimizing the length of the construction corridor that is active, maximizing the potential for learning and maximizing the cycling of key construction resources. However, substantial difficulties can be encountered in the form of delayed property acqui~itions, multiple regulatory jurisdictions, changing geotechnical conditions, overhead and underground utilities, work day and work week restrictions, and traffic control, to name a few. These difficulties make an orderly location sequence hard to maintain. Their impacts on a construction plan and schedule can be disastrous, and can lead to significant deiays and substantially increased costs. These difficulties are often compounded by the fasttrack nature of such projects. Increasingly, they are being procured using some sort of public-private partnership arrangement, such as BOT or designbuild.
