The cost of the new football stadium the New York Giants and New York Jets will jointly build in the Meadowlands likely will top $1 billion. Owners of both teams filed preliminary site plans Monday for the new 81,000-seat stadium, to be built between the existing Giants Stadium and the Meadowlands Racetrack. The teams are still working on design details, and they have yet to determine whether a retractable roof will be part of the plan. The stadium, which will be paid for by the teams, is the first in NFL history to be jointly built by two franchises, and is due to open for the 2010 season. Both teams currently use Giants Stadium. The new stadium will be served by a New Jersey Transit rail station connected to a transfer station, potentially bringing 10,000 fans per hour into the stadium by train. The state is not contributing to the cost of the stadium, but is kicking in about $225 million worth of infrastructure improvements, including building a rail station and paying for road upgrades within the sports complex and on nearby roads.