It will take longer and cost more than first thought to build the proposed Metrorail line through Tysons Corner.

Contractor Dulles Transit Partners and Metro officials say construction will begin in March and will be finished in July 2013, nearly a year later than originally planned.

Meanwhile, rising construction costs have added $54 million to the total price tag, which has risen to $1.63 billion. The federal government has given tentative approval to spending $900 million for the project.