The so-called traffic jam is known as pack racing and is endemic to NASCAR’s races at Daytona and Talladega. Since there tracks are fast and large, NASCAR ends up fitting all the engines with restrictor plates. What this does is cuts off airflow to the engine and also reduces horsepower. Cars run in these gigantic packs because this process slows the speeds of the cars. All it takes is for one car to make a wrong move and they will take out the entire field.
While this may explain the technical reason for yesterday’s crash, you still need the one driver who makes the mistake that causes the pandemonium and wreckage. That person was defending series champion Tony Stewart as he took the blame for causing the accident. “I just screwed up. I turned down across … Michael (Waltrip) and crashed the whole field. It was my fault blocking to try to stay where I was. I was trying to win the race. Michael got a great run on the bottom, a big head of steam. When I turned down, I turned down across Michael’s race car. Just a mistake on my part that cost a lot of people.”