Fixed systems win on throughput, mobile systems win on flexibility, and vehicle-mounted systems win where the inspection point moves. If you inspect more than about 60 container vehicles a day at one gate, fixed is cheaper per truck; below that, a relocatable or mobile unit usually pays for itself faster.
| Form | Throughput | Site works | Best for |
|---|---|---|---|
| Fixed | up to 150–200 trucks per hour | Concrete pit, shielding, dedicated lane | Ports, major land borders |
| Relocatable | around 30–60 per hour | Flat hardstanding, crane lift between sites | Seasonal or multi-site inspection |
| Vehicle-mounted | similar to relocatable | None beyond a parking area | Roadside checks, emergency deployment |
Daily volume. A fixed system needs civil works and a dedicated lane; that cost is only recovered when trucks queue through it all day. Below roughly 60 trucks a day the fixed installation rarely pays back inside its service life.
Whether the inspection point moves. Customs and border agencies often need to shift coverage between gates. A relocatable unit can be craned onto a new pad in days; a fixed one cannot move at all.
Penetration requirement. Fully loaded containers need high-energy systems (6 MeV class and above). Mobile units exist at that energy, but they are heavier and need a larger exclusion zone.
Regulatory perimeter. The controlled area around the beam depends on energy and shielding. A fixed site can build shielding into the structure; a mobile unit relies on distance, which means more space.
Compare the total of: equipment, civil works, lane construction, shielding, operator building, power supply, and the annual cost of the exclusion zone. A fixed system is often the cheapest per scan and the most expensive to abandon.
Can a mobile unit reach the same image quality as fixed? At the same energy and detector specification, yes; the difference is throughput and site logistics, not image quality.
How long does a fixed installation take? From civil works to acceptance, typically several months; the equipment itself is the shorter part.
Do we need a pit? Not always — some fixed systems scan from the side without a pit, at the cost of lane width and throughput.
Fixed and relocatable container scanners: FJ-PDS600. Fixed cargo and vehicle systems: FG series.
