What Is a Sally Port and How Is It Designed for Secure Transfer?

A sally port is a secure enclosed vehicle bay for in-custody transfer, designed with interlocked gates that never open simultaneously, hardened concrete construction rated for vehicle impact, and a direct secure path to holding cells. The bay must fit the largest transport vehicle with operating clearance for both gates. The sally port is the facility's most security-critical exterior opening — it's a hole in the secure perimeter big enough to drive through, so everything about its design exists to make sure that hole is never actually open.

The interlock is the heart of the design: two gates, one always closed, enforced by controls with position feedback. Around it, the enclosure is reinforced concrete designed for vehicle impact — walls, gates, and frames sized to stop a determined vehicle, not just to look secure. The civil design handles the approach: turning radii and queuing for transport buses, sight lines for the control room or officer operating the gates, lighting for nighttime operations, and drainage for the bay. The approach has to keep the transport vehicle out of public view and public access as much as the site allows — the transfer is a vulnerable moment, and the site plan should treat it that way.

Sally ports are small but they're pure security engineering — there's no room for approximate design. The checklist:

• Bay sized for the largest fleet vehicle with gate operating clearance — verified against actual vehicle dimensions
• Interlocked gate controls with position sensors, CCTV, intercom, and emergency manual override
• Reinforced concrete enclosure designed for vehicle impact loads, tied into the facility's secure perimeter
• Direct secure connection to holding cells with no public exposure along the path
• Civil design for turning radii, queuing, lighting, and bay drainage with washdown capability