The Minnesota Department of Transportation has swapped out static roadside signs that alert motorists on Interstate 35 near Faribault, Minn., that they are approaching a work zone and replaced them with much larger digital message boards.

To grab drivers' attention, the agency last week also placed temporary adhesive rumble strips on the pavement about 1,500 feet before vehicles pass each of the 10 digital warning signs.

"They have that tactile feel on the wheel, and you hear the sound," MnDOT spokesman Mike Dougherty said about the strips. "You hopefully look up as you approach the signs, and that it [the work zone] is less of a surprise."

MnDOT is resurfacing the freeway between Rice County Road 48 and Hwy. 21 this summer and next and has shifted traffic to one side of the freeway. But some drivers have not heeded or seen the warnings and the result has been deadly. Four fatal crashes at merging points have killed five people since July 12.

Crash reports, which may help identify the factors that led to the multi-vehicle wrecks, can take weeks to complete and are pending. MnDOT is eager to receive the State Patrol's findings, but needed to act, Dougherty said.

"In the short term we wanted to do something," Dougherty said. "Thousands of drivers get through safely, but there are a small number people who have not detected traffic slowing down or that there is a work zone ahead. Were there factors there that caused a crash versus others that did see it and maneuvered through?"

Drivers are first alerted to construction 10 miles before arriving at the merge point. Then starting five miles out and every mile after, drivers pass additional warning signs that flash when traffic is backed up or speeds have dropped to 50 mph or slower.

In the final mile are a series of signs instructing drivers to use both lanes and zipper merge at a designated point.

Dougherty said he hopes the larger signs on the shoulder will be what's needed to keep drivers safe and alive.

"What changed for the four fatals, awareness or inattentiveness?," Dougherty said. "Were there instances for whatever reason they didn't see the signs or were they distracted?"

MnDOT is working with law enforcement to increase their presence in the area, Dougherty said.

Drivers also have a role to play, he added. Dougherty suggested drivers alter their travel times if possible to avoid late afternoon when traffic is at its peak. He also said drivers need to obey the speed limit, allow for a safe following distance, avoid distractions and check at to be aware of current traffic conditions.

Construction will end in late October or early November but will return next season. Over the winter, "we will look at any adjustment or improvements and do anything and everything we have to have drivers' attention."