Diehard U2 fans angling for prime stage-side field positions at Saturday's Aloha Stadium show may be, to paraphrase one of the band's songs, stuck in a line that they can't get out of.

Fans with general admission field tickets will be allowed to line up outside stadium turnstiles from 6 p.m. Friday and remain overnight.

Stadium entry won't begin until 5 p.m. Saturday, when general admission and reserved seat ticket holders will be admitted in separate lines.

"The (general admission line) will be cordoned off, so there's no question who's in what part of the line," said Aloha Stadium Authority spokesman Patrick Leonard. "We want to ensure that when we finally let people on the field that it's not going to be a running free-for-all.

"It's going to be very orchestrated. We'll have security and ushers guiding people down to field level to make sure there's none of that."

The general admission entry plan mirrors concert promoter Live Nation's procedures at other stops along U2's Vertigo Tour, Leonard said.

"They have a very detailed venue safety and security requirement that they shared with us," Leonard said. "We've been meeting with representatives of the promoters to go over this procedure. ... They've assured us that this has worked at hundreds of venues around the world."

A food and beverage concession stand near the general admission ticket line will open at 6 p.m. Friday and remain open until showtime Saturday.

Restroom facilities near the concession stand also will be open, and portable toilets will be provided.

Security guards will monitor the line until the stadium turnstiles open.

The stadium's lower Halawa lot, across from Stadium Mall, also will open at 6 p.m. Friday to allow overnight parking at $5 per car. If the lot is filled, other lots will be opened for overnight parking. Tailgating will not be permitted at any time.

All stadium parking lots will open at 4 p.m. on Saturday.

No one will be allowed on stadium property before 6 p.m. Friday.

Prohibited items include weapons, fireworks, coolers, air horns, umbrellas, cans, bottles, or any outside food or beverages. Backpacks and purses will be allowed but will be inspected, possibly delaying entry. There will be an express lane at the turnstile for fans without bags.

"Dress comfortably, because it's going to be a long evening," Leonard advised folks planning on waiting in line overnight. "I'm sure it'll be fun for some. But obviously, if there are thousands of people, it's going to be an interesting evening.

"Bring a toothbrush."

Reach Derek Paiva at dpaiva@honoluluadvertiser.com.