Construction has continued on the $6 billion Baltimore & Potomac Tunnel Replacement program, according to a Tuesday announcement. That included eliminating an intermediate ventilation facility and a smaller tunnel connecting it to reduce construction impacts on the community. Construction progressIn the last year, work advanced on the new Mulberry Street railroad bridge, the first of five being reconstructed as part of the overall program, Amtrak said. That job includes new tracks and railroad infrastructure south of the future tunnel. “Replacing the 153-year-old B&P Tunnel is critical to improving safety and reliability along the Northeast Corridor, America’s busiest passenger railroad,” Roger Harris, Amtrak president, said in the release.