Motorists who’ve grown accustomed to traffic lights in central Connecticut that flash either amber or red in the late-night hours should brace for a change over the next couple of years.

At more than 70 intersections, the state will be switching the lights back to a regular green-amber-red pattern around the clock.

That means drivers can no longer expect caution signals on the busiest road at those crossings, a change that state transportation officials expect will cut down on accidents.

“Research shows a regular timed signal at intersections reduces crashes up to 50%,” said Josh Morgan, a spokesman for the state Department of Transportation.

The DOT announced that next summer it will seek contractors to revamp traffic signals at 72 intersections in 25 separate towns and cities from as far north as Enfield down to Glastonbury and Durham.

When the work is done, drivers in the overnight hours will no longer be allowed to cruise through flashing amber lights along the more heavily used state routes. But when they reach a red light, their wait should be fairly brief because next-generation sensors and cameras are also being installed, according to the DOT.

Like many states, Connecticut programs traffic lights along many of its state roadways to operate in a standard green-amber-red cycle from dawn to late at night — but then changes the pattern from late night until dawn.

During those overnight hours when traffic is light, signals automatically switch so they only flash. Drivers approaching from either direction on the busiest road get a flashing yellow, which allows them to keep going but only with caution. Drivers approaching along the other road get a flashing red light all night long: It’s intended to be treated as a stop sign, so drivers may go through only after making sure it’s safe.

When the roads are nearly deserted in the pre-dawn hours, that can mean a big time savings since through-traffic never has to wait through an entire red cycle. Those waits can be especially frustrating for drivers stuck at a traffic light that’s been programmed with a long red cycle; they might sit for a minute and a half or even longer even though no other cars are on the road.

Even so, some states and cities have been doing away with that flashing overnight system because of excessive accidents.

Sometimes drivers don’t fully stop for a flashing red, researchers determined. Others assume that cars from all four directions are facing a flashing red, and make only a cursory stop before accelerating again — even when cars are approaching from the cross street.

Crashes also happen because some drivers facing a flashing yellow aren’t sure what it means or else speed through the intersection without paying attention to cars that might have begun crossing or turning from the side.

In the past decade, Austin, Texas, and Winnipeg, Canada, were among the cities that cited safety when they did away with flashing nighttime signals in favor of traditional timing. The city of Colorado Springs, Col. advises motorists “For your safety, the city does not put signals on flash late at night. As a safer alternative, the city’s signals are equipped with vehicle detectors and remain green for the major street unless crossing traffic is detected.”

Ten years ago, the Federal Highway Administration reviewed numerous studies and concluded that injuries, deaths and front-impact collisions were all reduced when the standard green-amber-red signal pattern replaced  LNF — late-night flash — mode.

“Discontinuing LNF operations results in substantial reductions in crashes during late night periods,” its report said.

In Connecticut, the changeover will mean much more than flipping a switch or adjusting a timer. At each intersection, the DOT will install a 360-degree camera on the support arms that hold up the light. The camera will detect traffic and switch a red signal to green relatively quickly after it determines no cross traffic is approaching, the DOT said.

The new signals also will get so-called dilemma zone detection radar units.

“You’re in the dilemma zone when you’re on the road and the light turns from green to yellow; now you have to make a decision to stop or go. That’s the internal dilemma,” Morgan said.

The new equipment will have sensors that detect an approaching car in that zone and will briefly delay switching the cross street’s signal to green.

Nationally as well as in Connecticut, motorists in the past few years have increasingly complained about other drivers running yellow or red lights.

“We were seeing this before the pandemic, but now certain driving behaviors have really, really gotten bad:  red light running, speeding and aggressive driving,” Morgan said.

The DOT has already converted lights at 200 intersections to the new system, and expects to do the next 72 in 2025.

“This advanced technology will improve signalized intersection timing, and help reduce both nighttime and dilemma zone crashes,” said DOT Project Manager John Lockaby.

The intersections all are along state highways and are in Berlin, Bloomfield, Bristol, Cheshire, Cromwell, Durham, East Hartford, Enfield, Glastonbury, Hartford, Manchester, Meriden, Middletown, New Britain, Newington, Plainville, Rocky Hill, Somers, South Windsor, Southington, Tolland, Vernon, West Hartford, Wethersfield and Windsor.