BAGHDAD - The bland job description is "route clearance," but it is one of the most unglamorous and dangerous missions in Iraq. Creeping along the scarred streets of Sadr City, the soldiers search for roadside bombs around the clock, using bright spotlights at night that make them a big, bright target.

"We are lit up like the sun at night," said Spc. Chance Guzman, a forklift driver in a St. Louis scrap yard before his National Guard unit, the 1138th Engineer Company, deployed to Iraq from Missouri.

He spoke after a night mission during which his platoon found two bombs, or improvised explosive devices, as they are known by the military; avoided the blast from a third bomb; took gunfire from an alley; and eluded two mortar rounds.

The unit's mission is crucial as fighting continues between U.S. soldiers and Shiite militias in Sadr City, the densely populated Shiite neighborhood. As they have done successfully to tamp down violence in other parts of Baghdad, U.S. forces are erecting a massive wall, which is to be a dividing line between the militia-controlled areas to the north and the safe zone that U.S. and Iraqi forces want to establish to the south.

Route clearance teams have been opening the way for the construction while working to keep the streets south of the barrier free of bombs that the militias keep trying to sneak into trash heaps, wedge against curbs or otherwise hide in the ample debris in the streets. Most of the time the soldiers find the bombs before they explode, but sometimes the bombs find them, producing powerful blasts that rock their armored vehicles and reverberate through the streets.

"Given where we are at, the amount of action we are seeing and the amount of detonations on the vehicles, we are amazingly fortunate," said Lt. Carter Job Roberts, the leader of the company's 27-member 1st Platoon.

Good fortune, however, is a relative notion in Baghdad. Several members of the platoon have already earned Purple Hearts, and one gunner was lost to a rocket-propelled grenade.

"We're bullet magnets," said Spc. Michael Jason McMillan, a Missouri college student whose studies have been interrupted by two deployments to Iraq. He was hit by shrapnel in the arm and above the lip while manning the turret during a mission in October but was soon back on duty.

One night in late April, the bomb-clearing platoon set off on Al Quds Street, a four-lane thoroughfare where the wall is being built. The militias' bomb of choice is the explosively formed penetrator, a devastatingly effective weapon, which can penetrate many types of armor and which U.S. intelligence asserts is supplied by Iran.

But bombs are not the only worry. Armed with rocket-propelled grenades, small arms and mortars, militia fighters are often primed to attack when an American or Iraqi vehicle is stopped by a bomb blast.

Guzman carried a few talismans for an extra measure of protection: a religious pendant given to him by his father, the star from an old American flag that was sent by schoolchildren back home and an ace of spades playing card that was fixed to his helmet.

The militias are well-practiced at employing the bombs. One tactic is to place a bomb, or a decoy, in a visible portion of the road to distract the soldiers and divert them into the path of a powerful hidden explosive.

Constant attacks by Apache helicopters and Predator drones have taken their toll on the militia fighters, who often do not have enough time to carefully camouflage the bombs they try to sneak into the streets the Americans have already cleared.

"The ones that are hard to find are in the areas we have not been in yet," said Roberts, alluding to streets such as Al Quds.