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i <br /> 1 <br /> <br /> ~ ~ T e cost calculations for typical street intersections were based on the lineal foot unit <br /> <br /> i ~ c sts for different street widths and typical right-of--way widths for local and <br /> c (lector/arterial streets. Based on the average number of intersections per mile, the <br /> i tersection cost per lane mile of arterial/collector streets including administration and <br /> ~ e gineering costs can be estimated. <br /> N to that the average number of intersections does not include the downtown grid. It <br /> s judged unlikely that the dense grid system of streets in downtown Eugene would be <br /> <br /> ~ r peated elsewhere and thus avoids the potential for overestimating the number of <br /> in ersections per mile. <br /> <br /> ~ 1.3.3 Traffic Signal Costs <br /> <br /> ~ T e City of Eugene keeps track of the total number of intersections with and without <br /> tr ffic signals currently in place for all streets in the Urban Growth Boundary (UGB). <br /> R cords are maintained to account for the portion of state highway system jurisdiction <br /> s parately from the City's local jurisdiction. Signalized intersections on state highways <br /> ich intersect with Eugene's arterial and collector streets each count as one-half of a <br /> si nal for purposes of SDC calculation. The total equivalent signals equal the total <br /> si nals under Eugene's jurisdiction plus one-half of the shared jurisdiction signals. <br /> Di iding the total equivalent signals by the total number of lane miles of arterial and <br /> c (lector streets (a figure derived from Eugene maintenance records after subtracting <br /> to lanes from the inventory), yields the total percent of signalized intersections per lane <br /> m le. <br /> i <br /> O ce again, it was judged unlikely that the density of signalized intersections in the <br /> d wntown area would be repeated in newly-developing parts of the City. Accordingly, <br /> th number of signalized intersections per mile was reduced to reflect this factor. <br /> E timates for the average cost of signalization per intersection include administrative and <br /> ~ en ineering costs. This estimated average cost is multiplied by the percent of signalized <br /> int rsections per lane mile to calculate a component cost per lane mile for traffic signals. <br /> Th s cost per lane mile for signalization is added to the cost per lane mile of arterial and <br /> <br /> ~ co lector streets. <br /> 1. .4 Bridges and Other Structure Costs <br /> It s likely that additional bridges will be constructed as development occurs. It is <br /> as umed that bridges required for new development will be in proportion to existing <br /> de elopment, based on the City of Eugene's inventory of its bridge system, including <br /> Fe Street Bridge and overpass. <br /> Se eral of the bridges are on local streets and are, therefore, not appropriately included <br /> in he cost calculation for arterial and collector streets. It was also judged unlikely that <br /> th close spacing of bridges over the Mill Race and Amazon Channel in the vicinity of <br /> do town Eugene would be repeated in newly-developing areas. Accordingly, half of the <br /> sh rt-span bridges in the central Eugene area were eliminated from the cost calculation. <br /> In ddition to the small structures, the Ferry Street Bridge and the Ferry Street Overpass <br /> we a listed in the inventory. Construction costs were totaled, including administration <br /> ~ an engineering costs, and the total cost was divided by the total lane miles for the City's <br /> art rial and collector system, yielding an average cost per lane mile for bridge structures. <br /> 'I <br /> 'I <br /> May 1, 1997 City of Eugene SDC Methodology Page C-6 <br /> 'I <br /> <br />