A train approaches the Silver Line’s Wiehle-Reston East station during a tour in Monday. (Matt McClain/The Washington Post)

The contractor building the first phase of the Silver Line said that it has made “significant progress” and could ask the Metropolitan Washington Airports Authority as early as Wednesday to certify that the work on the rail line is complete.

The announcement by Bechtel late Tuesday was the strongest signal yet that some of the problems that have plagued the launch of the long-awaited rail line have been corrected.

Last month, MWAA found that hundreds of speakers installed in the new rail system had to be torn out and replaced because they did not meet fire code. Earlier, test trains struck a handrail and boxes containing emergency cutoff switches.

Larry Melton, Bechtel’s executive director on the project, said Tuesday that the work was “complicated somewhat by the fact that the new rail line must connect to the existing Metro system.” He added that “these challenges have been addressed,” enabling Dulles Transit Partners to submit the paperwork for completion.

Once the transit partners submit their documentation, MWAA officials will have 15 days to verify the project is complete.

This is the second time that Dulles Transit Partners has announced they have completed work on the $5.6 billion Silver Line. An early effort in February was rejected by MWAA when the contractor failed to meet seven out of the 12 requirements for certification.

But after that early rejection, MWAA officials made it clear that they would work closely with the transit partners to ensure that their second submission would be their final one.

The announcement Tuesday means that DTP could avoid the costly embarrassment of having to pay thousands in fines for delivering the rail line seven months past its September due date. MWAA officials had said that Bechtel could face $25,000 a day in fines if it failed to deliver the project by April 9.

The Silver Line is the first new line to be added to the Metro system in more than two decades It is also the first addition to the system that was not built by Metro.

Once MWAA certifies that DTP has completed its work on the first phase of the rail line, it will have to negotiate with officials at Metro, which has its own requirements that must be fulfilled before it will agree to take control of the rail line.

Metro will then have 90 days to do testing and training. Metro General Manager Richard Sarles this week hinted that the transit authority may not require all 90 days to complete its work but would not say for certain when the rail line would open.

Officials from the Federal Transit Administration and the Tri-State Oversight Committee will also conduct safety analysis.

The first phase of the rail line will include four stops in Tysons Corner and one in Reston at Wiehle Avenue.

Drivers on the Dulles Toll Road will pay for the majority of the project’s cost, but funding is also being provided by MWAA, Fairfax and Loudoun counties, and the state of Virginia.

The federal government contributed $900 million to the first phase of the project, which is expected to cost $2.9 billion.