Fox has yet to greenlight the Tony Scott-directed drama Unstoppable, which will star Denzel Washington and Chris Pine. Originally set to start production in August for a summer 2010 release, the studio is taking another look at the budget before starting produciton.

According to Variety, the picture centers on a young conductor and a veteran engineer who chase a runaway train filled with toxic chemicals.

The studio is wrestling hard with the cost of mounting a big-scale action pic plus the star salaries of Scott, Washington and Pine, who chose this film as his first since his breakout role as Captain Kirk in Star Trek. Studio is optimistic that it will get the film off the ground, but fall is now a more realistic starting point.