Traffic Planners in urban areas have three options for establishing new arteries or expanding existing lines: to locate them at grade, to elevate them or to put them underground. Unfortunately, capital costs are usually the governing factor used for deciding which option to use. As environmental, social and real estate issues are increasingly getting into the equation as do maintenance and operational costs, planners may look underground for the solution.
As seen in the attached tables, tunnel construction costs are more than at grade or elevated structures, however when lifespan and maintenance costs are factored in, the tunnel option becomes very competitive.
Table 1: Capital Cost
Table 2: Annual Cost