Construction can create its own negative benefits.
Most transportation projects today are not new facilities but instead improvements on or replacements of existing facilities. Any construction along a transportation corridor is likely to impose negative benefits to the public in the form of an increase in travel times, a decrease in travel time reliability, an increase in vehicle operating costs, an increase in air pollution, an increase in traffic accidents, and/or an increase in noise. These effects are referred to here as Disbenefits of Construction (Transport Canada (1994) refers to these negative benefits as "Transitional Effects" in their guide to benefit-cost analysis). If these negative benefits are present in a transportation project, their effects should be included in a benefit-cost analysis.
The same methods used to evaluate the benefits of a transportation project can be used to estimate the effects of construction. For example, if a project's construction slows vehicle speeds along a freeway for one year, the change in speeds and the volume of traffic can be used to calculate the value of the change in travel times, changes in vehicle emissions, and changes in vehicle operating costs. If the project creates more hazardous road conditions, an increase in accidents should be taken into account. The negative benefits associated with noise can also be estimated. These benefits (most likely negative) should be added to the overall benefits of the project.
The magnitude of the negative benefits associated with construction can be a significant determinant in choosing transportation project alternatives, particularly if different construction methods are considered. For example, in the case of widening an arterial, if construction is performed at night, some of the negative effects on congestion could be avoided. However, nighttime construction could be more costly (due to increased labor costs, etc.). A thorough benefit-cost analysis would account for these differences and aid in selecting the most cost-effective construction method.
Ginger Daniels, William R. Stockton and Robert Hundley (2000), “Estimating Road User Costs Associated With Highway Construction Projects,” Transportation Research Record 1732, (www.trb.org), pp. 70-79; summary at http://trb.metapress.com/content/h571k160r13242vm.
Barbara McCann, Bianca DeLille, Hank Dittmar and Michelle Garland (1999), Road Work Ahead; Is Construction Worth The Wait, Surface Transportation Policy Project (www.transact.org); at www.transact.org/report.asp?id=166.
Rhonda Kae Young, Chris Wolffing and Michael Tomasini (2005), “Highway Construction Impacts On Wyoming Businesses,” Transportation Research Record 1924, Transportation Research Board (www.trb.org), pp. 94-102.
Brian ten Siethoff and Kara M. Kockelman (2002), “Property Values And Highway Expansion: Timing, Size, Location, And Use Effects,” Transportation Research Record 1812, TRB (www.trb.org), pp. 191-200; at www.ce.utexas.edu/prof/kockelman/public_html/TRB02US183propvalues.pdf.
Transport Canada. Guide to Benefit-Cost Analysis in Transport Canada. Economic Evaluation Branch, Transport Canada, Ottawa, 1994. Available at: http://www.tc.gc.ca/finance/BCA/en/TOC_e.htm.