C-DRONE GUIDE · 1 AUGUST 2026
Port gantry crane drone inspection: STS, RTG, salt corrosion, VGP, price
A quay gantry crane sometimes tops eighty metres, hit day and night by sea spray and salt that eat away at the paint and start corrosion long before a structural disorder becomes visible from the ground. Yard cranes (RTG), mobile harbour cranes and quay gantry cranes (STS) all age in the same aggressive environment, under the same economic constraint: every hour a handling machine sits idle costs a terminal running at full tilt. Traditional rope-access or lift inspection remains essential for the mandatory statutory check, but it takes the machine out of service for hours and puts a technician at considerable height. A drone documents the structure, the lattice, the cables and even the travel rails in a fraction of that time, without durably halting operations. Here is what it inspects, what it does not replace, and prices observed in 2026.
Published on 1 August 2026, reviewed on 9 August 2026 — regulations in force as of August 2026.
What deteriorates on a port gantry crane: salt corrosion, fatigue, connections
A quay gantry crane (a « ship-to-shore » or STS crane) is a lattice or box-girder structure several dozen metres tall, mounted on a travelling chassis that runs the length of the quay on its own rails; a yard crane (RTG, rubber-tyred gantry) fills the same role in the storage yard, on tyres rather than rails; a mobile harbour crane, mounted on a slewing pedestal, rounds out the fleet for smaller vessels. All three work continuous cycles under permanent sea spray and salt haze, with the same weak points: the bolted connections between legs and sill beam, often high-strength friction-grip bolts whose progressive loosening goes unnoticed from the ground; the welds at the lattice nodes, fatigue-loaded on every lifting cycle; the trolley runway and the hoist-rope sheaves, exposed to wear and contact corrosion; and, at ground level, the machine's own travel rails and bogie wheels, whose misalignment often goes unnoticed until an incident.
The salt-laden atmosphere makes everything worse: salt accelerates corrosion well beyond the splash zone alone, including at the top of the structure, and hides early rust under blistered paint that is hard to distinguish from the ground or even through binoculars. That difficulty in reading the structure visually is exactly what drove the first drone crane-inspection work: a study by Maboudi, Alamouri, De Arriba López, Bajauri, Berger and Gerke published in 2021 in the ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences details a structured flight protocol around a container gantry crane and the automatic classification of rust areas by supervised learning from the collected images (see the study on Google Scholar).
Why the drone, on a machine that never really stops
On a terminal, a gantry crane standing idle is counted in tens of thousands of euros of lost productivity per hour while a vessel waits at the quay: lifeline inspection, which means climbing inside the legs and then moving along the boom, takes the machine out of service for hours and needs a rope-access technician certified for maritime work at height. A drone flown a few metres from the structure covers the same surface in a fraction of the time: legs, boom, machine house, trolley, festoon cabling and even the spreader and its twistlocks are photographed from every useful angle, often during an ordinary operational lull between two vessels rather than a scheduled shutdown.
The benefit goes beyond machine availability: a review published in 2023 in Applied Geomatics by De Arriba López, Maboudi, Achanccaray and Gerke describes an automated processing chain that registers drone images onto a 3D model of the gantry crane to precisely locate each detected defect — corrosion, cracking, flaking — and track its evolution from one campaign to the next, a capacity for tracking change over time that a one-off human inspection does not document as finely (see the study on Google Scholar). For an operator running several gantry cranes, that traceability matters as much as the time saved on any one flight.
The statutory check: what the drone does not replace
In France, any lifting equipment used in port operations — quay gantry crane, yard crane, mobile harbour crane — is lifting equipment within the meaning of the Labour Code: it is therefore subject to the mandatory periodic inspection (VGP) set out in articles R.4323-23 to R.4323-27 and in the order of 1 March 2004 as amended, carried out by a qualified person at a frequency that depends on the type of machine — generally annual for these fixed, high-capacity machines. It includes an examination of the state of conservation, static and dynamic load tests, and functional tests that a drone cannot perform: it measures neither a cable's mechanical strength, nor a weld's internal condition, nor whether the end-of-travel safeties work correctly.
The drone is therefore a complementary tool, used ahead of time to prepare for the inspector's visit by flagging points that deserve particular attention, or between two statutory checks to track how an already identified anomaly evolves without mobilising a rope-access technician for every check. The georeferenced photo report feeds into the machine's follow-up file, alongside the statutory inspection report — the only document with legal standing in the event of an inspection or accident. For cranes and gantries outside the port context, the same complementary logic applies: see our guides to construction crane inspection and factory overhead cranes.
Prices observed in 2026
Ranges observed in 2026 (excl. VAT):
- Inspection of a quay gantry crane (STS) (legs, boom, machine house, trolley, photo report organised by zone): €1,200 to €2,500.
- Inspection of a yard crane (RTG) or a mobile harbour crane: €500 to €1,100.
- Multi-machine framework agreement (a terminal's whole fleet, annual campaign synchronised with statutory checks): tapering rate per machine, on quotation.
- Post-incident record (vessel impact, gust of wind, reported damage) with a dated photo report: €600 to €1,200.
Access to the port enclosure and coordination with handling operations are the responsibility of the port authority or the terminal operator, on top of the usual flight authorisation — a point to settle at first contact, since a port often sits next to an aerodrome or a regulated airspace zone. Our structural drone inspection page presents this family of services; request a quote stating the type of machine, its height and the terminal's access constraints.
Frequently asked questions
Can the drone inspect a gantry crane during a full unloading operation?
No: the trolley and spreader must be locked in a known position and the machine paused for the duration of the flight, both for the pilot's safety and for image sharpness. The slot is usually fitted into an ordinary operational lull agreed with the quay supervisor rather than a dedicated shutdown.
Who authorises the flight inside the port enclosure?
Two separate authorisations are needed: the usual flight authorisation (open or specific category depending on proximity to an aerodrome, with a Géoportail drone-map check) and the port authority's or terminal operator's agreement for access to the enclosure and coordination with ongoing handling operations.