Missouri transportation officials are warning drivers that construction projects will cause delays on Interstate 70 between Kansas City and St. Louis this summer.

The state is encouraging drivers to avoid using the interstate at peak travel times on Friday and Sunday afternoons. It says delays of up to an hour are possible in some areas.

Alternate routes include U.S. 50 south of the interstate or U.S. 36 to the north.

The Missouri Department of Transportation says the main cause of congestion will be work on bridges over the Blackwater River near Marshall Junction.

Work on the westbound bridge is expected to be finished in mid-August, with the eastbound lane finished in mid-October.

Fontanis, ThinkStock