A conveyor gallery: elevated or at grade is decided by the crossings

By Johnny · 23 October 2026 · 6 min read

Every conveyor project settles the same argument before anything is drawn: run the belt on a steel gallery in the air, or put it on the ground under a cover.

It is usually settled by comparing tonnage of steel, which is the least informative comparison available. The two options are not variations of one design. They are two different answers to the question of what the belt has to cross — roads, rail, drainage, other conveyors, and the movement of people and machines underneath. Once the crossings are known, the answer is mostly forced.

Count the crossings before you compare the steel

An elevated gallery exists to keep a clearance. That is its entire justification, and it is a strong one when the belt has to pass over a haul road, a rail line, a public route or a second conveyor.

A gallery also has to be supported, and every support is a foundation in a place where something else wanted to be. Between two crossings, the support spacing decides how many of those foundations you buy. A span of 24 m (80 ft) between towers instead of 12 m (40 ft) halves the number of foundations and the number of transfer points that need attention — and it changes the gallery from a simple truss into a structure that has to be designed for its own deflection.

The at-grade option has the opposite profile: almost no structure, but a belt that has to be fenced along its whole length, crossed by every access route it meets, and protected from vehicles that will eventually hit it.

Clearance is a vehicle question with a maintenance margin

Where an elevated gallery crosses a road, the clearance is set by the tallest vehicle plus its load, plus the sag of the gallery under load, plus a margin for resurfacing.

That last item is the one people forget. A road that is resurfaced twice over ten years reduces the clearance under a fixed gallery by the thickness of two overlays, and a gallery that was tight at the start becomes a gallery that gets hit. Designing 500 mm (20 in) of spare height costs a little steel and avoids a repair that requires closing the road.

The same logic applies to the gallery's own access: a walkway alongside the belt needs headroom, a handrail, and a way to get onto it that is not a ladder to the roof. An elevated gallery without a proper access tower is a maintenance liability disguised as a structure.

What the belt does to the structure

A conveyor is a machine that lives inside a building, and it loads that building in ways a normal industrial shed is not loaded.

Starting and stopping produces longitudinal forces along the belt line. A long gallery on tall towers behaves like a beam on flexible supports, and the towers take those forces into foundations that may not have been designed for them. Belt tension at a turn or a drive station can be large enough to matter, and it arrives at a specific point rather than distributed along the length.

The structural answer is to decide where the horizontal forces are resisted — one braced tower, not all of them — and to make sure the gallery's connection to that tower can take the load while the others are allowed to slide. A gallery pinned at every tower will crack its welds at the ends of the run.

At grade: the belt is cheap, the fence is not

A ground-level conveyor is structurally almost free. What it costs is everything around it.

It needs a fence along both sides for its whole length, and that fence needs a gate wherever a person or a vehicle has to cross. It needs a cover to keep rain off the material, and that cover is a structure in its own right — light, long, and loaded by wind exactly where it is least stiff. It needs crossings: bridges over the belt at intervals, each of which is a small structure with its own foundations.

And it needs protection from the site. A belt at ground level on a site with haul trucks is a belt that will be run into, and the damage is rarely to the belt alone.

Where the ground is flat, the crossings are few and the material is not weather-sensitive, at-grade wins clearly. Where any of those three is untrue, the elevated gallery usually wins on total cost even though its steel is heavier.

Transfer points are where both options lose money

Whatever the configuration, material has to change direction somewhere, and the transfer point is where dust, spillage and wear concentrate.

An elevated gallery puts every transfer point in the air, which is good for the belt and bad for maintenance: a chute that blocks at height is a stoppage that needs a platform, a crane or a rope. A ground-level belt puts transfers at a height a person can reach, but spreads them across the site where they are harder to supervise.

The useful rule is to keep the number of transfers as low as the layout allows, and to design each one with a maintenance position — a platform with a handrail at the right height, and a place to put the tools. That is a detail on a drawing, and it decides whether the plant runs or stops.

What I want before drawings

• A plan of everything the belt must cross, with the clearance each crossing requires.
• The drive and tension stations, and the forces they put into the structure.
• The material: bulk density, moisture, and whether it is abrasive or sticky.
• How maintenance reaches every transfer point and every idler.
• Whether the route will change, or a second belt will be added alongside.
• The wind speed to be used, taken from the applicable code at the project site rather than a round number, plus the gallery's open-side detail — a long, narrow, open-sided gallery on tall towers is the most wind-sensitive element on a bulk site, and its fixings at the towers take the load first.

Elevated or at grade is not a preference. Count the crossings, measure the clearances, and the site will tell you which one it wants.