Four years ago this month, construction of Phase 1 of the Dulles Corridor Metrorail Project began. Today project construction is 89 percent complete.

Station structures are in place at the four stations in Tysons Corner and one at Wiehle Avenue in Reston. Track work is virtually complete. Tunnels to carry trains below the Route 7/123 intersection are done. Pedestrian bridges to carry passengers and pedestrians across Routes 7 and 123 and the Dulles Airport Highway Corridor have been installed.

What remains are the finishing touches: installing the systems that will make stations accessible to users and ensure that the trains run safely, including intensive work where the new line, now called the Silver Line,

will merge with Metro's existing Orange Line near I-66 and the Dulles Connector Road. That work is extremely dangerous because it is taking place next to the operating Orange Line.

Testing is well under way, starting with the December running of the first WMATA clearance car along the alignment from Wiehle Avenue to East Falls Church.

Project Director Patrick Nowakowski says he expects construction to be completed in late summer and then the project will be turned over to the Washington Metropolitan Area Transit Authority (WMATA) for additional testing. WMATA will set the actual opening date.

Meanwhile, between now and opening, train cars will be visible in the corridor as testing continues. Some weekend disruptions of Orange Line service will be needed to complete the Orange Line tie-in.