Baltimore-Washington Parkway Widening Feasibility Study

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Baltimore-Washington Parkway Widening Feasibility StudyPhysical ConstraintsMD 193 Bridge Would Require ReconstructionGood Luck Road Bridge Would Require ReconstructionPotential Property Impacts in Greenbelt, Maryland56 November 2012
Baltimore-Washington Parkway Widening Feasibility StudyPhysical Constraints6.3PreliminaryCostsIn order to address the feasibility of widening the B-W Parkway, the potential benefits need to becompared to the estimated capital costs. Below is a summary of the methodologies and assumptionsthat were used to develop the preliminary capital cost estimates for each of the four widening optionspresented in the feasibility study.6.3.1CapitalCostsPreliminary capital cost estimates for each widening option were developed using the MarylandDepartment of Transportation State Highway Administration 2011 Highway Construction CostEstimating Manual. The recommended format for conceptual or feasibility study planning level projectcost estimates is a Major Quantities Estimate. Overall, base costs were developed by applying current2011 unit costs to measurable quantities of major item categories that included earthwork, paving,shoulders (curb, traffic barrier, guardrail, etc.) and structures (bridge widening, new construction,demolition). Other categories of costs were estimated by applying recommended percentages of theoverall base cost of the major items. The percentages used were based primarily on the rangessuggested in the 2011 Highway Construction Cost Estimating Manual prepared by Maryland SHA. Insome cases, where additional items within a category could be measured or estimated by lane-mile orlength of project, they were included and the corresponding percentage adjusted.The Maryland SHA 2011 Highway Construction Cost Estimating Manual breaks down the total projectcost into eight separate cost categories, or groups of similar items. For the purposes of this initial costcalculation, only four of the categories (2, 4, 5 and 6) are considered major items and their combinedcategory costs are included as the defined “major item costs.” A brief description of the itemsconsidered and quantified within each category for this feasibility study or the applicable percentage ofthe major item costs are provided below:Category 1 Preliminary: mobilization, clearing and grubbing, engineer’s office, andmaintenance of traffic were considered to be 40 percent of the major item cost.Category 2 Earthwork: the earthwork volumes were estimated by average end method fromcut-and-fill areas computed from preliminary cross sections and Geopak design software. Thecross sections included a widened roadside ditch section to account for stormwatermanagement, using environmental site design, to meet the new MDE guidelines.Category 3 Drainage: the drainage (storm drain pipes, inlets, etc.) was estimated as 30 percentof the major item cost. Stormwater management, using environmental site design, to meet thenew MDE guidelines is accounted for in this percentage.Category 4 Structures: the areas of bridge removal, bridge widening, and new bridgeconstruction were measured from the feasibility study plans.57 November 2012
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