San Diego

Motorists who take northbound California 163 to westbound Interstate 8 in Mission Valley will have to take an alternative route for the next four months. The ramp connecting the two was scheduled to be closed by midnight Monday, a California Department of Transportation spokesman said.

The ramp taking cars to I-8 is to be torn down, and a new one will be built as part of an $18.5-million interchange expansion project, said Caltrans spokesman Tom Nipper.

“The current bridge is too small,” Nipper said. “We’re trying to plan ahead for whatever traffic might be there in future years.”

About 9,000 cars use the ramp daily. Detour signs will be posted to help motorists find their way to westbound I-8 from northbound California 163.

Suggested alternate routes:

* Exit at the Friars Road interchange and come back on southbound California 163 to I-8.

* Take Friars Road west to Fashion Valley Road, then to I-8.

* Get on I-8 eastbound to Mission Center Road and turn around to get on I-8 westbound.

* Take Friars Road east to Mission Center Road and then to I-8.

Caltrans officials said the ramp closing shouldn’t cause any major tie-ups.

“It’s one of our lighter-traveled ones compared to other freeway connectors,” said Rick Hopkins, a Caltrans engineer.