here's john bentley. [horn honks] >> reporter: with only inches to spare, this huge tanker squeezed past a bus through the salang tunnel. the badly-rutted road can jam trucks against the rocks or tip them over. drivers can wait for more than a week to get through this dangerous mountain pass. despite the risks, coalition troops rely on the tunnel for 85% of their fuel. this is the best route available since pakistan closed its borders to nato trucks seven months ago. since then a tunnel built for 1,000 vehicles a day has ten times that traffic. afghan general mohammad rajab is in charge of maintenance on the pass. "it's just one accident away from disaster," he said, "and unless something is done soon, it will be impossible for the tunnel to function." the tunnel has no light and the ventilation system doesn't work. the air is choked with such high levels of carbon monoxide that some passengers get sick. while there are other routes through the hindu kush mountains, this is the only one that's protected,

john bentley takes us through the dangerous passageway that's a lifeline for nato forces in afghanistan. keeping your eye on the road and not the dashboard. mark strassmann on new federal guidelines targeting distracted drivers. and lasting image, 40 years after this vietnam war photo shocked the world, the photographer and his subject meet again. tony guida has the story. captioning sponsored by cbs this is the "cbs evening news." >> axelrod: good evening. i'm jim axelrod. the fighting in syria is widening tonight and claiming still more civilian lives. more than 50 today alone according to one activist group. more than a dozen people are reported dead in the southern city of deraa, and today there was combat, as well new york damascus itself. elizabeth palmer is there. >> reporter: united nations observers arrived in syria supposedly to monitor a ceasefire. instead they're documenting constant fighting. today they drove to an outer suburb of damascus, mehleha, and immediately a crowd formed to point out the damage they say syrian soldiers did last night. there are in what looked like