The new security measures were a response to last month's deadly Boston Marathon bombings.
Speedway officials and Indiana State Police didn't immediately return calls from The Associated Press seeking comment. State police told WTHR that late arrivals caused the bottlenecks.
Some fans reported security officials quit checking belongings as the start of the race neared. John Bumstead of Logansport, Ind., says officials "opened the floodgates" as the race approached.