Early plans called for a tunnel running from the east of the station to the west of the station, and for all four stations on that stretch to be below ground. When the contractor hired to design the Silver Line – a consortium of Bechtel and Washington Group International – found the costs to be too high, the design was changed to use a short tunnel, running only between the and stations (underneath higher ground) with all four stations being at or above ground. In March 2006, the contractor was ordered to examine an alternative "large bore" tunnel digging technique (successfully used in Europe) with the potential to lower costs of a tunnel through the entire Tysons section. The contractor found that there would not be a significant cost reduction and proposed staying with the short tunnel option.