Baltimore-Washington Parkway Widening Feasibility Study

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Baltimore-Washington Parkway Widening Feasibility StudyPhysical ConstraintsCategory 5 Pavement: the areas of new pavement for the widening and the areas of existingpavement to be milled and overlaid were measured from the feasibility study plans. From theseareas, quantities of aggregate base, base asphalt and surface asphalt were computed.Category 6 Shoulders: this category includes curb, gutter, traffic barriers, guardrail, andappurtenances. Though not designed or shown on the plans at a feasibility study level,quantities for these items were estimated using engineering judgment and the cross sections’dimensions.Category 7 Landscaping: this category includes an allowance for normal roadside landscapeitems estimated as 10 percent of the major item cost. It also includes the reforestation of theimpacted forested areas measured within the limits of disturbance shown on the feasibilitystudy plans. For purposes of this estimate, an acre of mitigation or replacement was assumedfor every acre of impacted forest. This category also includes an estimate for anticipated noisewalls. A length of noise walls along potential sensitive sound receptors (adjacent residentialcommunities) was approximated and multiplied by an average height of 15 feet. The total costof these three components comprises the landscaping category.Category 8 Traffic: pavement markings, markers, signs and guide signs were estimated basedon project lane lengths. No lighting or traffic signal equipment are anticipated or included inthis estimate for the widening as neither items exist on the current parkway.Category 9 Utilities: utility relocation was estimated as 8 percent of the major item cost.Due to the preliminary nature of this estimate, a contingency cost of 40 percent was added to the sumof the above categories to provide an overall “Neat” cost. Preliminary engineering (10 percent) andconstruction overhead (15.5 percent) costs were also included in the overall capital cost estimate basedon percentages of the total “Neat” cost. A summary of the capital cost estimate is illustrated below.Preliminary Capital Cost Estimate (2011 Dollars) 6(in millions of dollars)Cost Elements AASHTO/SHA NPSInside Outside Inside OutsideConstruction Costs $ 326 $ 450 $ 274 $ 427Preliminary Engineering $ 33 $ 45 $ 27 $ 43Construction Administration $ 51 $ 70 $ 42 $ 66Total Costs $ 410 $ 565 $ 343 $ 5366 For additional cost estimate details, see Appendix G58 November 2012
Baltimore-Washington Parkway Widening Feasibility StudyPhysical ConstraintsBased on the capital cost calculations, the outside widening options will cost more than the insidewidening options. The AASHTO widening options will cost more than the NPS widening options. Thedifference in cost is due mostly to the wider shoulder impacts resulting from the use of the AASHTOdesign standards in comparison to the NPS standards. This impact would affect both northbound andsouthbound widening. It should also be noted that these costs exclude estimates of potential right-ofwayacquisition or other cost factors previously noted.6.3.2RightofWayCostsThe potential right-of-way impacts identified were very narrow sliver encroachments adjacent to theB-W Parkway boundary. It is anticipated that if this study should advance to a more detailed designthat these impacts could be avoided and therefore no costs for right-of-way acquisition are included inthe study.6.3.3OperationsandMaintenanceCostsThe widening of the parkway will increase the pavement area by about 35 lane-miles and the surfacearea of associated bridge structures will be increased accordingly. As a result, the annual operations andmaintenance cost budget for the Parkway would likely increase by about $300,000 to $400,000. Thiscost was estimated by applying the increased number of lane miles and structure areas to unit pricestaken from the 2011 operations and maintenance budget, provided by the NPS. This cost includes laborand materials for typical parkway maintenance items such as mowing grass, applying road salt andannual bridge maintenance.6.3.4ConstructionCostsforParkAestheticsGiven the context of the parkway, additional costs were included in the estimate for landscaping andaesthetic treatment of structures. For the NPS alternatives, the cost of roadside barriers was estimatedto account for the decorative concrete/stone treatments. For bridges, an additional $20 per square footwas added to the cost estimate to account for the aesthetic architectural treatments of piers andabutments. The estimated landscaping cost was increased to account for plantings indicative of aparkway.59 November 2012
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Baltimore-Washington Parkway Widening Feasibility Study

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