Baltimore-Washington Parkway Widening Feasibility Study

Baltimore-Washington Parkway Widening Feasibility StudyPhysical Constraints6.0PhysicalConstraintsThe physical constraints for widening the B-W Parkway 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 Parkway.6.1ApproachestoWideningApplying the typical sections for each of the four widening options along the existing B-W Parkwayalignment revealed several types of impacts and limitations due to the existing conditions. Generally, ifthe Parkway passes over a cross-street, the existing bridges will need to be widened. If the Parkwaypasses 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 Parkway 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 Parkway.6.2PotentialImpactsThe table below summarizes the levels of reconstruction anticipated for each widening option.Expected Infrastructure Impacts Per Widening OptionInterchange Reconstruction Bridge Widening 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