An aggressive effort to overhaul the aging Metro system in Washington, D.C., is producing results as it nears the one-year mark, with more than 28,000 cross-ties and nearly two miles of grout pads now replaced.
The 117-mile system has undergone a series of power-system fires, derailments and other disruptions. The causes range from a lack of a dedicated funding source to a philosophy among former Washington Metropolitan Transportation Agency (WMATA) administrators to prioritize operations over upkeep.
Because it can moderate the damaging effects of earthquakes, base-isolation is a technique used primarily in seismically active regions. ENR takes a look at some of the largest applications of base-isolation technologies in the world.