Procedures that provide for a quantitative calculation of system benefits derived from both infrastructure and mobility projects are described. The procedures were used by the Capital District Transportation Committee (CDTC) in Albany, New York, as part of a comprehensive project evaluation process in the development of its 1993-98 Transportation Improvement Program. The technique involves the use of CDTC's regional travel simulation model to estimate system-level impacts of transportation actions; these impacts include changes in travel time, delay, excess delay, operating costs, accident costs, and vehicular emissions. Metropolitan transportation organiza-_ tions typically use such calculations to examine the value of mobility projects (highway widenings, signal system improvements, new highway or transit facilities, and other projects that add capacity), but CDTC uses similar calculations to capture the system benefit of repair or replacement of bridges, highways, and transit equipment. This method allows for head-to-head comparison of mobility improvement and infrastructure repair projects. In the CDTC process, the system value of a bridge, highway, or transit service renewal proposal is estimated by simulating system conditions both with and without the facility or service proposed for repair or replacement. The difference between system conditions with the facility (or equipment) in place and with the facility removed is then prorated to reflect the percentage· of the natural life of the facility that is extended by the project. For example, if a facility's physical life is 50 years and the repair extends its life 20 years, the system benefit of the repair project is calculated at 40 percent of the calculated system value of the facility.

The Capital District Transportation Committee (CDTC) is the designated metropolitan planning organization (MPO) for the area containing the Albany-Schenectady-Troy, New York, urbanized area. During 1992 CDTC and New York State defined CDTC's metropolitan area boundary as Albany, Rensselaer, Saratoga, and Schenectady counties (with the exception of a small part of Saratoga County, which is within the Glens Falls urbanized area). The total population of CDTC's defined metropolitan area is in excess of 750,000, and the entire area is designated as a marginal nonattainment area for ozone.