Perched on the Leeds Avenue overpass, North Charleston Police Pfc. Matt Woodall aimed his laser speed-tracking device at oncoming eastbound vehicles on Interstate 526.

“Lane two, 71 miles per hour, silver Lexus,” he said.

The information was radioed to waiting traffic enforcement officers. A cruiser accelerated down the on-ramp and closed on the speeder, blue lights flashing.

“People have got to slow down. If you have got to be somewhere, leave 15 minutes early,” said Maj. K. Coyle Kinard.

The pattern of tracking speeders and pulling them over for ticketing proceeded at a steady pace at mid-afternoon Friday.

A motorcyclist was clocked at 139 mph heading toward Mount Pleasant.

“That’s the fastest speed I’ve seen on the Mark Clark. We never caught him. There was no way we could catch up to him,” Kinard said. “He either got on Interstate 26 or went straight into Mount Pleasant.”

At the other end of the speed spectrum, police stopped a bicyclist riding illegally along I-526 toward Savannah Highway.

Kinard said the traffic enforcement patrol was not happening because two people died in crashes on the interstate this week. The operation was planned before those wrecks occurred as part of an ongoing enforcement strategy on I-526.

“Periodically, we will do radar operations to have people slow down. It’s not just going to be today,” he said. “It will be steady enforcement on the Mark Clark.”

In response to the police presence, tractor-trailers were running a bit under 55 mph in a 60-mph zone, he said.

Police and sheriff’s deputies from North Charleston, Charleston and Charleston County participated in the speeding crackdown aimed at calming traffic and improving safety on the busy artery.

Combined, the agencies wrote 216 tickets during the daylong operation, mostly for speeding. Five people were arrested, Kinard said.

Two people were killed in wrecks Sunday and Monday on the interstate. Both resulted in felony arrests. Each crash shut down the interstate for several hours.

Another wreck on I-526 snarled rush-hour traffic Wednesday, but nobody was seriously hurt, according to Charleston police. A motorcycle heading toward North Charleston from West Ashley ran into the back of a pickup truck that was slowing down near the Leeds Avenue exit about 5:10 p.m., police said. The accident stalled traffic in both lanes.

On Friday at about 4 p.m., traffic had slowed to a crawl on I-526 westbound at Leeds as commuters headed to West Ashley. North Charleston Police Sgt. M.T. Morgan said the sudden drop in speed that happens when traffic stacks up is a contributing factor in rear-end collisions.

“This is part of the problem,” he said. “You’ve got cars going 25 miles per hour.”

The North Charleston police presence on I-526 eastbound included five cruisers, an unmarked car and a motorcycle parked along the Leeds Avenue on-ramp. Deputies were conducting I-526 traffic enforcement operations from the westbound Leeds Avenue ramp.

As Woodall called out speeds and descriptions of eastbound cars on I-526, Morgan said there was no acceptable speed over the posted limit of 60 mph.

“South Carolina is zero tolerance,” he said. “Technically, anything over the speed limit is citable.”

The history of fatalities on I-526 includes a fiery crash on July 13, 2007, that killed five people. The incident occurred during afternoon rush hour amid an influx of eastbound traffic from North Rhett Avenue.

An 18-wheeler slammed into the rear of a car merging onto I-526. The car and a van went under the truck. Another car was trapped between the truck and a wall that runs along the entrance ramp. The truck exploded into flames that consumed the van and two cars.