How a lock-up runs
The key set PA assigns positions before the first rehearsal, often sketched on the back of the call sheet. On a sidewalk scene outside a diner, a fictional plan might be:
| Position | PA | Covers |
|---|---|---|
| North corner, Ventura and Fulton | Chris | Pedestrians walking south |
| South driveway | Dana | Pedestrians and cars exiting lot |
| Diner back door | Sam | Kitchen staff and crew traffic |
| Base camp path | Lee | Crew walking to set |
The 1st AD's calls on the walkie follow a pattern: "Lock it up, we're going for picture." Each PA answers "Locked" or reports a problem ("Hold on the north corner, stroller coming"). When cut is called: "Cut. Release." PAs let people through, and repeat the cycle for the next take.
Scheduling and the lock-up
Lock-ups affect how long a location takes. A busy commercial street at lunch hour means more interruptions and slower takes than the same street at 9:00A. When an AD estimates how many setups fit before lunch at a practical location, experience with the street's traffic matters as much as the page count.
The number of PAs also sets limits. With four PAs, you can hold four access points. If the shot is a wide that sees a whole block, the location manager may need a permit condition for intermittent traffic control and police or authorized personnel to hold cars. That goes into the film permit and the cost report.
Mistakes and friction
Being rude to the public is the fastest way to lose a location. Ask, explain it's about a minute, thank people. A neighbor who gets shouted at can call the film office and cost the production its next permit.
Another common mistake is locking up too early. If a PA holds pedestrians while camera is still adjusting focus, people wait for several minutes and eventually walk through anyway. Wait for the AD's call.
Crew are part of the lock-up too. A grip crossing behind camera during a take is still a ruined take. Lock-ups sit alongside the location lockdown, which controls the location perimeter for the whole day, and walkie discipline on the right channels.