Variations of CT
There are essentially two different versions of road-rail Combined Transport. A distinction is made between
- unaccompanied transport, in which only the intermodal loading unit, i.e. container, swap body or cranable semi-trailer, is transported by rail, and
- accompanied transport (Rolling Road), in which the loading unit is transported along with the tractor unit and the driver spends the rest period in the couchette.
The best-known form of Combined Transport is with containers, swap bodies and semi-trailers. This unaccompanied transport, in which only the loading units are conveyed by rail, now accounts for well over 90 per cent of the market in road-rail Combined Transport across Europe.
A loading unit for unaccompanied Combined Transport is taken a short distance by road to a Combined Transport terminal and dropped off there. The operator takes the loading unit, loads it onto a goods wagon, assembles the train and transports the loading unit over the long distance to the destination region. At the destination terminal the loading unit is switched from the train to the road vehicle – with or without brief interim storage. The loading unit is not accompanied by a truck driver during the rail leg.
The following loading units are used in unaccompanied transport today:
- Overseas containers in hinterland transport
- Swap bodies and land containers in purely continental transport
- Semi-trailers that are cranable as a result of technical modifications
Accompanied transport (Rolling Road)
Accompanied Combined Transport, also known by the term "Rolling Road", is the transport by rail of complete trucks, i.e. loading unit plus tractor unit.
The distinctive technical feature of this transport model lies in the series of coupled low-loader wagons with a continuous cargo area across which lorries are able to drive. One by one, the truckers drive up an end-loading ramp and across the continuous cargo area to their parking spot. Before the train journey begins, the truck drivers go to the couchette, where they are able to spend their rest period. The duration of the railway leg is recognised as a break period by legislation in a number of countries. The drivers return to their cabs at the destination, drive down the end-loading ramp and continue on their way by road.
These systems have considerable economic and technical disadvantages on many routes compared to unaccompanied transport. The restricted tunnel profile in Europe necessitates the use of complete goods vehicles and tractor-trailers with a very low loading area. They must also have extremely small wheels. This entails substantial expenditure in terms of the design of wheels and brake systems. Staffing costs – up to a point – are also incurred for the truck drivers during long-distance transport by rail. Another significant drawback with the Rolling Road consists in the high “dead load”, as the weight of the whole truck must be transported as well as its cargo. This significantly limits the cost-effectiveness of the system. Today, Rolling Roads exist mainly in places where their geographical location offers more benefits than road haulage alone and they are given financial support in the form of government subsidies.