From supposedly reliable intelligence, Abrams was able to follow the progress of troops and supplies south, and judge where and when the North planned to attack over the border into Vietnam. To paraphrase from A Better War, Lewis Sorley: Troops advanced south in waves 500 to 600, moving at 12.2 kilometers per day, mostly by foot, the trucks saved for supplies and ammunition. We were able to move perhaps 60 Kilometers on the unimproved section, partly because our load was not on our feet, but on our bicycle, and partly because we had no backup supplies; we had to get out of that jungle in short order.
Our risk was nothing compared to the average Laotian farmer, wandering children, firewood gathering women, who know their next footstep can mean death, or for some worse, maiming, in a poor country where everyone must contribute.
Some facts: 270 million of these bombies were dropped on a country the size of Utah. Of the more than 50,000 people killed or maimed by the bombings, 20,000 have occurred after the end of the war. An average of one person a day is killed or maimed in Laos now, nearly 40 years later.