Mid-design, Union Pacific Railroad required either a $4-million crash wall and detection system or a 50-ft setback, revised from the previous standard of 20 ft. That put the tracks even closer to the backs of a number of homes, despite easements purchased by Sacramento RT. To limit train motion and dissipate any rumbling, LAN's design called for 400 ft of ballast-mat vibration dampers, composed of a resilient layer over a load-distribution layer.

Underground Obstacles

In an area near a Pacific Gas & Electric valve lot, 22-ft-deep, soldier-pile retaining walls prevented the need to relocate 20-in.-dia gas lines to the front of a neighborhood street. The piles maintain the structural integrity of the rail line in case the utility conducts pipeline maintenance.

To limit road closures and speed up construction of rail crossings, LAN used precast, full-depth concrete panels, also known as tub crossings, instead of ballast-tie construction. "The panels are particularly helpful when the ground includes unsuitable material and would take a long time to prepare," Abansado says. The units include ports that can be unscrewed to inject materials in case of settlement.

To streamline construction, crews built two bridges—the largest at 1,317 ft long and 40 ft tall—and a $31.5-million parking garage, while plans were still being modified for the rail portion. "Having those structures complete first eliminated risk and allowed us to keep moving ahead," says Ed Scofield, Sacramento RT's director of project management.

By partnering with utilities that "were willing to work with us, we should be able to open a little bit ahead of the scheduled date," Scofield adds. "Without that cooperation, the schedule would be shot."