Screening Bottleneck and Evacuation Across a Six-Lane Road
A four-storey urban courthouse handles 700 visitors and 350 staff daily. The only public entrance has two screening lanes, each nominally processing 150 persons per hour, but baggage and medical devices reduce that to about 110 in practice. Peak visitor flow is 180 per hour between 08:30 and 10:00, and 80 staff arrive in a 30-minute shift change through the same entrance. The building has a 45 m setback from the street, but the rideshare drop-off is 15 m from the glass lobby, and the mailroom is in the basement with a shared loading dock. There are panic alarms in six courtrooms but no separate employee entrance. The evacuation assembly point is across a six-lane road. After a credible vehicle-borne threat and a screening queue that reached the sidewalk, the court asks for a security and emergency review. The sheriff wants to keep two lanes and add a third only if justified.
1. Evaluate screening capacity and queue risk, and decide whether a third lane is justified.
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Practical capacity is 2 lanes × 110 persons/hour = 220 persons/hour. During the 30-minute shift change, visitor demand is 180/hour plus 80 staff in 0.5 hour, which is equivalent to 160 staff/hour. Combined peak demand is therefore about 340 persons/hour for that half hour, not 180. The excess is 120 persons/hour for 0.5 hour, so roughly 60 people accumulate before service catches up-enough to reach the sidewalk and create a target. A third lane at the same practical rate adds 110/hour, raising capacity to 330/hour; that still leaves a small deficit and no margin for a medical bag, an alarm, or a lane closure.
A third lane is therefore justified only as part of a package: separate or stagger the 80 staff arrivals, add a staff-only screening point or credential lane, and use a queue management layout that keeps the sidewalk clear. If the sheriff insists on two lanes, the court must reduce peak demand through staggered shifts and appointments and accept a residual queue. The decision should be based on the 95th-percentile morning, not the average daily count. Document the queue length trigger for opening a third lane.
2. Recommend vehicle standoff and evacuation changes, including the assembly point and mailroom risk.
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The 45 m setback is not effective if the rideshare drop-off is 15 m from the glass lobby. Relocate the drop-off beyond the standoff line or behind bollards, and treat the lobby glass as a fragilization risk rather than a protective barrier. Add vehicle mitigation at the actual approach path, not just at the property line. The mailroom and shared loading dock are a separate risk: separate mail intake from public vehicle traffic, screen packages off-site where feasible, and do not route mail through the public lobby.
The evacuation assembly point across a six-lane road is unsafe for a population that includes jurors, people with disabilities, and in-custody defendants. Designate an on-site or near-site assembly area that does not require crossing traffic, and provide a separate internal holding area for in-custody persons with deputy control. The six courtroom panic alarms should trigger a coded response that distinguishes a screening incident from a courtroom emergency. Rehearse a vehicle-borne threat scenario that includes closing the drop-off, moving the queue, and sheltering the lobby, not only a fire evacuation. The review should end with a tabletop exercise and a written trigger for when the third lane and alternate assembly point activate.