Transportation snarls have sent a vast expansion of the Tysons Corner Center back to the drawing board.

The Fairfax County Planning Commission, which reviews land-use proposals and recommends policy to the Board of Supervisors, forestalled a vote last week on rezoning about 80 acres of land on Route 123 in the heart of Tysons. A positive vote would have been a major step in green-lighting developer Macerich’s plan to bring 1,350 new homes, 200,000 square feet of retail and a 300-room hotel, as well as an array of public amenities and open space, to the already enormous mall over 10 to 15 years.