What Is an Open Top Container?

What Is an Open Top Container?

An open top container is a shipping container without a rigid roof, featuring a removable tarpaulin cover and a top-end door header that can be swung away, designed for cargo that is too tall to be loaded through standard container doors. The container's walls and floor are structurally identical to a standard dry container — built from corrugated Corten steel — but the roof is replaced by a reinforced tarpaulin sheet secured by ropes and eyelets along the top rails, with a bow-shaped roof arch to allow water runoff. The swing-away header at the door end allows a crane or overhead hoist to lower cargo directly into the container from above, which is critical for heavy or awkwardly shaped items that cannot be forklifted through rear doors.

How Open Top Containers Are Used

Open top containers solve a fundamental loading geometry problem: some cargo is simply too tall to pass through the 2.28 m high door opening of a standard 20-foot container (2.59 m for a high-cube). When cargo height exceeds these limits, the only practical loading method is from above using a crane, mobile harbour crane, or gantry. The open top design makes this possible while preserving the protective side walls that flat racks lack. This matters for cargo like heavy machinery, generators, steel fabrications, compactors, mining equipment parts, and oversize construction materials — items that are both tall and vulnerable to damage from the elements or shifting during transit.

After loading, the tarpaulin cover is secured over the cargo using lashing ropes threaded through eyelets along the top rails. The cover provides basic weather protection but is not watertight or structurally rated — it prevents rain ingress and offers shade, but cargo may still be exposed to condensation and is not protected against container stack loads. For this reason, open tops must be stowed so that nothing is placed on top of them, typically in the uppermost tier of an on-deck stow or the top cell of a hold stack. This top-tier-only constraint is the key trade-off shippers accept in exchange for the loading flexibility an open top provides.

Open Top vs. Flat Rack vs. Platform Container

Choosing between an open top, a flat rack, and a platform container depends on three dimensions of the cargo: height, width, and the need for side protection. An open top is best when the cargo fits within standard container width (2.35 m internal) but exceeds the standard door height — the side walls remain intact to provide lateral containment and attachment points for lashing. A flat rack has only a floor and fixed or collapsible end walls, making it suitable for cargo that is oversize in both width and height, but offering no side protection at all. A platform container is essentially a flat floor with corner castings and no walls whatsoever — used for the most extreme out-of-gauge (OOG) cargo where even end walls would obstruct loading. For cargo that is only tall (not wide), the open top provides the best balance of protection and accessibility at a lower freight cost than custom flat rack solutions.

Open Top Container Specifications and Port Handling

Standard open top containers are available in 20-foot and 40-foot sizes, with internal dimensions matching their dry container equivalents. A 20-foot open top typically offers an internal length of 5.90 m, width of 2.35 m, and floor-to-top-rail height of 2.35 m. The tare weight is slightly higher than a standard container of the same size due to the reinforced top rails and the weight of the tarpaulin and roof bow assembly. At port terminals, open tops require careful handling — the absence of a rigid roof means they cannot be stacked under other containers, and the tarpaulin must be inspected for security before vessel loading. Digital port systems, including GOTEC's terminal management platform, can flag open top bookings in the stowage planning module to ensure correct position assignment and to alert customs inspection teams about potential above-rail cargo protrusion that may require special scanning procedures.

Frequently Asked Questions

What is the maximum cargo height for an open top container?

Cargo loaded in an open top container can protrude above the container's side rails, subject to shipping line approval and route-specific height restrictions. Typical above-rail clearance may allow cargo to extend 30–50 cm beyond the container top, but the total height must still comply with the transport mode constraints — road bridges, rail tunnels, and vessel stowage positions all impose practical limits. It is essential to coordinate maximum cargo height with the carrier before booking an open top shipment.

How is an open top container different from a flat rack?

An open top container has rigid side walls and a floor like a standard container, but with a removable roof — making it suitable for tall cargo that needs side-wall protection and weather shielding via a tarpaulin cover. A flat rack, by contrast, has only a floor and end walls (fixed or collapsible), with no side walls. Open tops are preferred when cargo requires lateral containment and weather protection from above; flat racks are chosen for cargo that is both oversize in width and height, or that requires side access for loading.

Related Terms

• Flat Rack — A container with only a floor and end walls, no sides or roof, used for cargo that is oversize in width and height and requires side access.
• OOG — Out of Gauge; cargo that exceeds the standard dimensions of a container and requires specialized equipment such as open tops, flat racks, or platforms.
• Breakbulk — Non-containerized cargo shipped as individual pieces, often overlapping with the types of project cargo that open tops carry.
• Platform Container — A flat floor with corner castings and no walls, used for the most extreme oversize cargo where even end walls would obstruct loading.