Thunder Road was a popular place for the locals to drag-race.
However, the police knew that, and occasionally staked the location out, nabbing the illegal racers.
Last year the fuzz had Thunder Road staked out, and everybody got hauled to the clink.
So? Nobody's gonna catch Greased Lightning!
It was there that Kenickie and Leo Balmudo were to face off, "Race for Pinks" (Winner gets the other's car). Unfortunately, thanks to Jan finding a penny, but Marty Maraschino took it and tried to hand it to Kenickie, but she dropped it, he bent down to pick it up, and Putzie opened the door to Greased Lightning and wonked him on the head, knocking him out. He was too dizzy - minor head trauma - to race, and let Danny Zuko take over. So Danny raced Leo, and easily won, though Greased Lightning got pretty sliced up thanks to Leo's Hell's Chariot.
Note It's filming location is Los Angeles River Basin - Between 1st & 4th Street Bridges, Downtown, Los Angeles, California, USA
Note: In the scene where the cast are near the bridge after the car race, the water on the ground was stagnant and dangerous. Some cast members became ill from filming as the setting was a derelict place full of dirt and rubbish.