These excerpts are here to show the courage of the men under fire with the odds against them. Lest we forget.
Describing the work. Source: https://en.wikipedia.org/wiki/Battle_of_Heartbreak_Ridge
The preparations for operation Touchdown required a period of tremendous activity on the part of the 2nd Engineer Combat Battalion and its commander, Lt. Col. Robert W. Love. The road along the Mundung-ni Valley was a rough track unsuitable for the medium M4A3E8 Sherman tanks of the 72nd Tank Battalion and to get it quickly into condition to carry the Shermans was a herculean task, but Love and his men were willing to try if they had adequate fire cover while they worked. Craters dotted the track and the KPA had planted mines along the way. At one point they had heaped large rocks 6 feet (1.8 m) high and sprinkled the pile with hand grenades, each with its pin pulled. The 2nd Engineers put 110 pounds of explosives around this roadblock and detonated the grenades when the explosives went off. Rock from neighboring cliff walls was blasted to provide fill for the craters. Working with shovels because their bulldozers were undergoing repair and would, in any case, have drawn artillery fire from the KPA on the heights further up the valley, the engineers fashioned a usable road. To take care of the mines along the trail, they placed chain blocks of tetranol at 50 feet (15 m) intervals on the sides of the track and then set them off. The explosions detonated the mines nearby. When the craters and mines were too dense, the engineers shifted the road to the stream bed, which had not been mined, and cleared the boulders blocking the way. Bit by bit they advanced northward up the valley.

The Silver Star Citation William Rollins. Source: https://valor.militarytimes.com/hero/111440
The President of the United States of America, authorized by Act of Congress July 9, 1918, takes pride in presenting the Silver Star (Posthumously) to First Lieutenant (Corps of Engineers) William Rollins (ASN: 0-2206600), United States Army, for gallantry in action as a member of Company D, 2d Engineer Combat Battalion, 2d Infantry Division, in action against the enemy on 8 October 1951 in the vicinity of Saegonbae, Korea. On this date, Lieutenant Rollins was leading his platoon, which had the mission of clearing a route of access through a narrow defile in a river bed for friendly advancing armor. As the platoon demolished the rocks, smoke and debris from the explosion would mark the unit's position and intense enemy mortar and artillery fire were directed into the area. In spite of this furious hostile fire, Lieutenant Rollins continued to supervise and encourage his men in their work, and by remaining in an exposed position, he was an inspiration to his men. While leading his unit through the defile, Lieutenant Rollins was fatally wounded by enemy mortar fire, but as a result of his self-sacrificing action, the mission was successfully accomplished. The gallantry in action displayed by Lieutenant Rollins on this occasion reflect great credit upon himself and the military service.

The Bronze Star Cpl Robert G. Bartley. Source: https://ameddregiment.amedd.army.mil/bronzev/korea/korea_b.html
By direction of the President, under the provisions of Executive Order 9419, 4 February 1944 (Sec II WD Bul 3, 1944), and pursuant to authority contained in AR 600-45, the Bronze Star Medal with “V” device for heroic achievement in connection with military operations against an armed enemy of the United States during the period indicated is awarded to Corporal Robert G. Bartley, Army Medical Service, United States Army, a member of the Medical Detachment, 2d Engineer Combat Battalion, 2d Infantry Division, distinguished himself by heroic achievement on 9 October 1951, in the vicinity of Saegonbae, Korea. On this date Corporal Bartley, a medical aidman, was assigned to a friendly unit which had the mission of clearing a pass through a narrow defile. As the unit entered the defile, it was suddenly subjected to intense hostile artillery and mortar fire, wounding the platoon leader and his assistant. Corporal Bartley, with complete disregard for his own safety, went to the aid of the fallen men. With amazing rapidity, he organized a litter team to evacuate the wounded men from their exposed position. Although the officer [most likely was 1Lt William Rollins] died of his wounds before he could be evacuated, prompt action on the part of Corporal Bartley enabled the other man to be evacuated to safety. The outstanding devotion to duty and comrades displayed by Corporal Bartley on this occasion reflects great credit upon himself and the military service.