Optimising Dangerous Goods ISO Container Transport with Midland’s Drop Deck Skel A-Double
Transporting ISO containers—particularly those carrying Dangerous Goods (DG)—requires more than just strength and capacity. It demands engineering precision, compliance with regulatory standards, and optimisation for performance. At Midland Pty Ltd, we’ve developed a specialised 30-metre Drop Deck Skel A-Double trailer combination, tailored to meet these specific challenges while delivering superior payload performance across Australia's extensive PBS-approved freight networks.
Our latest innovation helps fleet operators, logistics companies, and DG transporters move more with certainty—safely, legally, and efficiently.
The Complexity of Transporting DG ISO Containers
The transportation of an ISO freight container is already a demanding task, but when these containers carry DG payloads, the requirements become far more stringent. Let’s break down the main factors that make this application so technically challenging:
1. Static Rollover Threshold (SRT) Requirements
DG goods must be transported with an SRT of 0.40g, compared to the 0.35g for non-DG PBS payloads, and no mandatory SRT for prescriptive non-DG loads. The higher SRT requirement ensures vehicle stability, but it also means DG containers must be carried lower to the ground—adding pressure to design for a lower centre of gravity (CoG) and compact trailer height.
Reference: National Heavy Vehicle Regulator – PBS Vehicles Carrying Dangerous Goods
2. Configurations of A-Double vs. B-Double
While A-Doubles are the preferred high-capacity configuration under 30 metres (compared to B-Doubles) due to better turning circles and higher payloads, they come with a key drawback: reduced roll stability. Unlike B-Doubles, which use a fifth wheel, A-Doubles rely on tow couplings between trailers—further complicating SRT compliance for Container DG loads.
3. Multi-Scenario Payload Balancing
To meet a wide range of freight requirements, trailers must support several container configurations:
One DG ISO container per trailer
One heavy 20-foot general freight container per trailer
Two empty ISO containers per trailer
One 40-foot general freight container on the rear trailer
Each case requires a separate mass distribution calculation to ensure axle weights and payload positioning remain compliant with PBS standards.
4. PBS Network Compatibility
All A-Doubles must conform to the reference vehicle dimensions and performance criteria of the nominated PBS network. This can mean trade-offs between length, payload capacity, and the positioning of the payload’s CoG. The ability to remain within 30m total combination length is critical to gain gazetted network access and maximise freight efficiency.
Midland Drop Deck Skel
Midland’s Engineered Solution: Drop Deck Skel A-Double for ISO Containers
At Midland, our in-house engineering team worked closely with transport operators, PBS assessors, and road authorities to develop a trailer solution that overcomes these barriers.
Our Drop Deck Skel A-Double is designed for both Dangerous Goods and general freight ISO container transport, and is currently PBS approved for operation on Level 2 High Productivity Freight Vehicle (HPFV) networks at the following capacities:
85.5 tonnes GCM at Higher Mass Limits (HML) for non-DG freight
82 tonnes GCM at HML for DG freight payloads
Explore our drop deck skel trailers for sale learn more about our PBS-approved trailer range.
Key Design Innovations
Perimeter Frame Construction
To lower the trailer deck height and meet SRT requirements, we’ve implemented a perimeter frame design that allows the trailer to nestle as close as possible to the truck chassis.
High Tensile Steel Integration
Strategic use of high tensile steel helps reduce tare weight, allowing for improved payload capacity without compromising structural integrity or trailer lifespan.
PBS Certification & Future Proofing
The trailer is designed with future upgrade potential. For even better DG performance, customers can select alternative airbag suspension systems or replace the dolly’s fifth wheel with a ballrace, further lowering height and improving stability.
Supported Container Configurations & Payloads
Our Drop Deck Skel A-Double supports the following configurations:
| Container Type | Trailer Configuration | Payload Capacity |
|---|---|---|
| DG ISO Containers | 1 per trailer | Up to 28.5 tonnes each |
| 20’ General Freight | 1 per trailer | Optimised for heavy loads |
| Empty ISO Containers | 2 per trailer | High-volume return loads |
| 40’ General Freight | 1 on rear trailer | Up to 29 tonnes |
