ANNAPOLIS -- The rush hour is over, the sun has slipped beneath the horizon and the temperature has dipped below 90 degrees.

Just before 8 p.m., a state trooper sets up flares along eastbound Route 50 near Route 2, diverting motorists into one lane. Minutes later, huge floodlights brighten the darkening sky. Engines whir and voices shout instructions over the din.

Behind Jersey barriers, the night shift construction crews start work.

For the past 14 months, crews have concentrated on Route 50, converting the four-lane highway to six lanes between Washington and the Chesapeake Bay bridge.

Working at night, the crews can accomplish much of what they cannot do during hot summer days, when temperatures and humidity prohibit them from pouring decks and paving roads.

Joe Pollock, 19, of Gettysburg, Pa., the son of the head foreman of the Baltimore-based Williams Construction Co. Inc., is the first to grab a two-yard bucket of wet concrete that is lowered to the workers.

He positions it over the steel grids and pulls a lever, letting loose the sticky gray mixture. Five or six men rush to spread and smooth the concrete, barely finishing one load before the next is poured. By daybreak, 77 yards of concrete, poured onto grids eight inches thick, will have passed through the workers' hands.

It's a tough way to make a living. Starting pay runs about $7 an hour and reaches $12 to $14 an hour for machine operators and carpenters. Construction workers don't make more when working at night.

Pollock and the rest of the crew already have worked a 10-hour day. "It's hard, but I don't plan on doing it forever," he said during a five-minute break for water, the only rest the crew had between 8 p.m. and 1 a.m., when the pouring was completed.

Shouting instructions over the noise of machinery and motorists, State Highway Administration Engineer Greg Phillips makes sure the crew doesn't miss a spot. An error could lead to cracks in the concrete.

Mike Polardy, the SHA engineer in charge of grading, checks the concrete to ensure it has the desired texture, and checks the sediment controls.

The cooler evenings are more comfortable, but hazardous.

In June, two motorists were killed when they misinterpreted detour signs on Route 50 and ran into a concrete barrier about 1 a.m. In Annapolis, most motorists have grown accustomed to slowing down between Route 450 and the Severn River Bridge, where construction is under way around the clock.

But for those who choose to ignore the warning lights, a state trooper is positioned at one end.

"People tend to get a little irritated when they are inconvenienced," Polardy said. "But in the long run, it'll make it a lot easier to go to Ocean City."