BANGKOK — For six decades, vendors have set up their stalls each evening along the same three blocks. A new rail station is now planned for the site, and the vendors want a guarantee they can return.

“Our customers come here because we are here,” said Somchai Wattana, who sells grilled fish from a stall his father opened in 1971. “If we move, they will not follow us.”

City officials said they are working on a plan that would integrate the market into the station plaza. Construction is due to begin next year.