State officials say they plan to install more signs on Storrow and Memorial drives to warn motorists of height restrictions on the two roadways.

Moving trucks, tractor-trailers, and even a duck boat have crashed into overpasses on the parkways that flank the Charles River.

Last Sunday, a duck boat crashed into an overpass on Storrow, causing the tourist vehicle to lose part of its roof. On Tuesday afternoon, an overheight box truck struck one of the overpasses.

Two more trucks hit overpasses on Soldiers Field Road on Friday.

Such “stuck truck’’ accidents, which some have also dubbed “Storrowing,’’ have become particularly common around the beginning of September each year as college students flood back to the area and others move into and out of apartments. Many moving trucks are too tall to fit under Storrow and Memorial overpasses, and drivers are often unfamiliar with the vehicles and the roads.

The state Department of Conservation and Recreation, which manages the parkways, recently surveyed signs posted along both roadways and is in the process of adding more to ensure that drivers get plenty of warning before they head toward any overpass with a clearance of less than 14 feet, 6 inches.

The effort includes identifying more locations where signs can be affixed directly to overpasses.

During a ride Wednesday afternoon along Storrow Drive’s eastbound side, no signage could be seen on at least three overpasses.

DCR officials say all entrances to Storrow Drive, which runs along the Boston side of the river, have overhead structures with hanging rubber flaps that display signs that say “Cars only,’’ “Danger low clearance,’’ or “No trucks or buses.’’

One entrance to the eastbound side of Storrow Drive, at Pinckney Street in Beacon Hill, that is not maintained by the DCR instead has a no-trucks sign posted.

Memorial Drive, along the Cambridge side of the river, also has overhead warning structures ahead of low overpasses.

In addition, signs are attached directly to many overpasses, and there are three locations where flashing lights with sensors and electronic messages warn truck drivers to exit, officials said.

In 2013, a bus carrying high school students slammed into a bridge over Soldiers Field Road, which is a western extension of Storrow Drive, injuring more than 30 people.

Steve Annear of the Globe staff contributed to this report. Matt Rocheleau can be reached at matthew.rocheleau@globe.com.