Looking Back at the Tunnel Timeline

Although the debate over whether to build a Metrorail extension to Dulles International Airport above- or below ground in Tysons Corner has flared only in the past year, key decisions on the project were made more than a decade ago.

1994 Virginia and Metro officials initiate a "major investment study" to evaluate rail options for the Dulles corridor. One of 12 options studied is an underground route through Tysons.

1997 The project team, including state, local and Metro officials, publishes a report rejecting an underground route through Tysons because of cost.

2000 Project officials hold three public meetings on the mostly aboveground recommended route. More than 400 people attend; only three submit comments in favor of a Tysons tunnel.

2002 The Fairfax County Board of Supervisors and Metro and state officials endorse a mostly aboveground route through Tysons.

January 2006 The state requests that the project's contractors estimate the cost of tunneling through Tysons using a wide-bore digging technology not previously considered.

April-May The contractors report that the technology would be prohibitively expensive. The Fairfax board seeks an independent evaluation. The state appoints an engineering panel to study a tunnel. (The panel endorses the tunnel.)

September Gov. Timothy M. Kaine (D) rejects a tunnel.

January Tunnel advocates produce engineering plans that they say prove a tunnel is feasible.