A portion of a new rail tunnel in Tysons Corner, Va., has settled about an inch, but recent tests show there is still the necessary clearance for a Metro train to pass, according to an inspection report. The tunnel is part of the first phase of the $5.6 billion Silver Line rail line project. Metropolitan Washington Airports Authority engineers and the Metro will review the findings in coming weeks. "At this point in time, right now, it looks all right," said Pat Nowakowski, chief construction manager on the Silver Line for MWAA. "It was built in accordance with the requirements."