NATIONAL GATEWAY CLEARANCE IMPROVEMENTS
12th Street, I-395 Ramp & 10th Street (L’Enfant Plaza)
Shirley Contracting Company, LLC was awarded a contract by Clark Construction Group, LLC and CSX Transportation to improve the vertical clearance between 7th Street SW and Maine Avenue SW, Washington, District of Columbia on CSXT’s Richmond Frederick & Potomac (RF&P) Subdivision via lowering the existing tracks to accommodate the largest presently available rail double stack and tri-level car carriers.
The vertical clearance improvements between 7th Street SW and Maine Avenue SW were achieved by Shirley by lowering the existing active tracks roughly three feet. The work was sequentially phased in five stages for the existing main tracks to be shifted to alternative alignments and or removed. The existing track bed was excavated down three feet, drainage installed, sub-ballast prepared, and ballast was installed to final elevation. New and temporary tracks were constructed by Clark and CSX on the prepared ballast, lined, and surfaced for the subsequent phases, and the disassembly and removal of track and material. The track lowering required the removal of portions of the existing on-site drainage system and the reconstruction of a new system to tie back into the existing stormwater system. Work also included the strengthening of the existing retaining wall at the northwest corner of the site for increased railroad surcharge loadings, the modification of the existing access ramp at the northwest corner of the site for improved construction access and its subsequent restoration. Additional retaining wall construction was required for onsite grade separation. Protection and relocation via the construction of an existing ductbank for the existing utilities, radio communication line, fiber optic cable, and electric power lines located with the railroad right of way was also completed. The work required for the protection of the existing manhole structures including the modification of one manhole to accommodate temporary grading and final site restoration.
Across the five phases of the Project a total of 30,000 tons of contaminated soil was hauled offsite, 10,000 tons of sub-ballast was imported and installed, 10,000 tons of ballast was imported and installed, and 2,000 feet of storm drain was installed along with 25 storm structures.