CHICAGO -- Officials in Chicago say Grateful Dead fans won't be allowed to camp out during three 50th anniversary concerts over the summer.

Fans had asked for overnight permits for parking lots around Soldier Field over the Fourth of July weekend.

Soldier Field spokesman Luca Serra tells the Chicago Tribune that safety was a top consideration in the decision not to grant permits.

Roughly 60,000 to 70,000 people are expected to attend each sold-out concert. Soldier Field doesn't usually have events later than 11 p.m., after which tailgating isn't allowed.

Serra says there will be increased security with police and fire crews for traffic management.

Soldier Field has allowed overnight parking just once -- for a 2007 college football game when some fans requested it.