Construction sties that block roads and snarl traffic when no actual work is going on would face fines under a bill being introduced Tuesday in the City Council.

The legislation, sponsored by Councilman Ben Kallos, would require that roadblocks like traffic cones, barrels and Jersey barriers only be set up in the street for one hour before and one hour after work is underway.

Kallos (D-Manhattan, photo) said drivers often encounter traffic backups caused by construction barriers and road closures, only to find the site empty.

“New Yorkers want to get where they are going fast. Everyone hates traffic jams, especially when they are for road work, but no one is actually there doing the work,” he said. “It’s about making sure we are only impeding traffic and causing traffic when we absolutely need to.”