Phase 2 of the Silver Line has just run into another major problem that could further delay a project that is already 13 months behind, according to a report.

The Washington Post reports that hundreds of concrete rail ties are flawed, a problem that the contractor and officials have known about since September but haven't been able to figure out a fix. The problem is that about 400 concrete ties that support the rails are as much as half an inch higher in the middle than on the ends, which may cause the tracks to tilt.

The contractor, Capital Rail Constructors, has proposed using shims to "even out" the tracks, but officials are not on board due to "significant" maintenance issues they believe would result, according to the report. Phase 2 of the Silver Line project -- which would extend to Reston Town Center, Herndon, Dulles International Airport, and Loudoun County -- is already more than a year behind schedule, with the RTC station not expected to open until 2020 at the earliest.

