The old track, which essentially is a joined chain of 39-foot-long pieces of rail dating back to the 1940s, will be replaced with continuous-welded rails. Each rail piece is 1,600 feet long, said project workers as they worked Sept. 11 near Badger Canyon Road.

The project will improve safety and ride quality for six trains that use the track every 24 hours, Melonas said.

The month-long project is being coordinated without affecting the usual traffic on the track, he said.

It's a high-tech mechanized operation, where machines help knock down rail anchors, pick up spikes and swing out old rail. The new rail is then laid out after filling spike holes and reshaping the ties mechanically. A crew of about two dozen works on about 5,000 feet of rail track each day.

BNSF is using recycled rail to replace the old track, which also will be refurbished and re-used.