How Is a Courthouse Sally Port Designed for Secure Transport?

The sally port's defining feature is the interlock between its exterior and interior openings. The control sequence is deliberate: the transport vehicle enters through the exterior gate, the gate closes and latches, and only then does the interior door to the holding corridor release. Sensors confirm each gate's position before the next step is allowed, and the logic is hardwired or programmed so a control failure defaults to all openings locked. The transfer path itself is engineered as a short, direct, fully secured corridor from the vehicle bay to the holding cells. The designer eliminates hiding spots and blind corners, keeps the path wide enough for restrained movement with officers on both sides, and separates it completely from public and staff circulation. Pedestrian sally doors along the path use the same interlock logic on a smaller scale, and every door position reports back to the central security station.

An enclosed vehicle bay fills with exhaust quickly, so the mechanical engineer sizes ventilation for the worst case: multiple diesel transport vehicles idling with the bay doors closed. Carbon monoxide and nitrogen dioxide detection stages the exhaust fans automatically, and makeup air is introduced so the fans can actually move air rather than pulling the bay into deep negative pressure. In cold regions, unit heaters or radiant heat keep officers and equipment functional without fighting the exhaust system. The floor is a working surface: sloped concrete to trench drains, hose bibbs for washdown, and separation of oily wastewater where the local authority requires it. Electrical design includes gate operators on emergency power, battery backup for the interlock controls, and lighting levels high enough for positive identification of every person in the bay. Commissioning tests the full sequence — vehicle entry, interlock timing, exhaust response to a simulated CO event, and drain flow — before the facility accepts its first transport.

A complete sally port package proves the secure transfer works under every condition: • Electrically interlocked exterior gate and interior door that can never open together • Short, direct, fully secured transfer path separated from public circulation • Exhaust ventilation sized for idling transport vehicles with CO/NO2 detection • Sloped floor with trench drains, washdown hose bibbs, and oil separation as required • Tamper-resistant high-output lighting and full CCTV coverage of the bay • Duress alarms on the transfer path tied to the courthouse security station • Gate operators and interlock controls on emergency power with fail-secure logic