<strong>Baltimore</strong>-<strong>Washington</strong> <strong>Parkway</strong> <strong>Widening</strong> <strong>Feasibility</strong> <strong>Study</strong>Physical Constraints6.0PhysicalConstraintsThe physical constraints for widening the B-W <strong>Parkway</strong> by adding a third lane in either direction arediscussed in this section. These constraints include the availability of land for the widening, the impactsto NPS-designated land, impacts to privately owned land, and impacts to existing infrastructure alongthe <strong>Parkway</strong>.6.1Approachesto<strong>Widening</strong>Applying the typical sections for each of the four widening options along the existing B-W <strong>Parkway</strong>alignment revealed several types of impacts and limitations due to the existing conditions. Generally, ifthe <strong>Parkway</strong> passes over a cross-street, the existing bridges will need to be widened. If the <strong>Parkway</strong>passes under the cross-street, then the entire overpass bridge will typically need to be replaced. Thereare some locations where the generally defined limits of disturbance are anticipated to encroach closeto, or to extend outside of, the existing B-W <strong>Parkway</strong> right-of-way.If the study advances, the assumption is that through more detailed design at a later stage, potentialimpacts could be mitigated such that relatively modest amounts of additional right-of-way would likelybe required for any of the four options. These mitigation methods could include, but not be limited to,such features as minor geometric alignment alterations, localized reduction of a stormwatermanagement buffer area, steepening of fill slopes, or even the construction of short sections ofretaining walls. The latter mitigation action has been employed on some areas of the GWMP, and itscompanion the Clara Barton <strong>Parkway</strong>.6.2PotentialImpactsThe table below summarizes the levels of reconstruction anticipated for each widening option.Expected Infrastructure Impacts Per <strong>Widening</strong> OptionInterchange Reconstruction Bridge <strong>Widening</strong> Bridge ReconstructionNPS AASHTO/SHA NPS AASHTO/SHA NPS AASHTO/SHAOutside Inside Outside Inside Outside Inside Outside Inside Outside Inside Outside Inside11 2 11 2 7 6 7 6 7 4 7 5With all four widening options, bridge widening would be required at Little Patuxent River, PatuxentRiver, MD 197, Powder Mill Road, Beaver Dam Road, Capital Beltway, and MD 410. Under both outsidewidening options, bridge reconstruction would be required at MD 175, MD 32, MD 198, Explorer Road,MD 193, Good Luck Road, and MD 450. Under the inside widening options, only the bridges at MD 32,Explorer Road, MD 193, Good Luck Road, and MD 450 would need total reconstruction. Partial54 November 2012
<strong>Baltimore</strong>-<strong>Washington</strong> <strong>Parkway</strong> <strong>Widening</strong> <strong>Feasibility</strong> <strong>Study</strong>Physical ConstraintsUnder the NPS inside widening option, the MD 175 Bridgewould require widening.interchange reconstruction involving areadjustment of the ramp gore areas, underthe outside widening options, would berequired at MD 175, MD 32, MD 198,Powder Mill Road, MD 193, Capital Beltway,MD 410 and MD 450. Under the insidewidening options, only the interchanges atMD 193 and MD 450 would requirereconstruction.<strong>Widening</strong> is constrained at several locationsinvolving the existing ramp configurations.<strong>Widening</strong> to the outside <strong>Parkway</strong> right-ofwaywill impact several existing loop ramps,such as at MD 175, MD 32, MD 198,MD 197, Explorer Road, MD 193 CapitalBeltway, MD 410, and MD 450. So as not to impact the turn radii on the loop ramps, these ramps wouldneed to be reconstructed if outside widening occurs.The limits of disturbance for the outsidewidening option will encroach upon theexisting B-W <strong>Parkway</strong> property rights-of-wayon both the northbound and southbounddirections at some locations between thePatuxent River and MD 198. The limits ofdisturbance encroaches upon thenorthbound right-of-way at the PatuxentResearch Refuge just north of Powder MillRoad, and between Explorer Road andBeaver Dam Road. The limits of disturbanceMD 450 Bridge would require reconstructionencroach upon the southbound right-of-wayadjacent to BARC between Beaver Dam Roadand Powder Mill Road. The limits of disturbance also encroach upon the right-of-way on bothnorthbound and southbound sides between Greenbelt Road and Explorer Road. The limits ofdisturbance encroach upon Greenbelt Park between Good Luck Road and the Capital Beltway.55 November 2012