El principio de paridad como elemento de la realización efectiva de la “Constitución

Road transport followed the line of local container development with even more consequence and changed both, the width and the length to allow for a maximum of cubic space. The length concept followed a calculation as follows:

allowed road train length 18 000 mm - truck-trailer coupling device 1 200 mm - driver’ s cabin incl. berth 2 500 mm

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either in 6 100 mm + 8 200 mm, or in 7 150 mm + 7 150 mm.

The first concept was near to the classic German road train with a 2 axle truck (with a 6,1 m loading length) + a 3 axle trailer (with a 8,2 m loading length). Soon it became evident that the system 7 150 mm + 7 150 mm was more practicable because the swap bodies of similar length could be easily exchanged between truck and trailer. In the end, the concept of 2 swap bodies of similar length was standardised in Germany and later in Europe (see chapter 1.2.2 and 1.2.3.).

The swap body is today moving some 65 % of all European intermodal volume. This success story has two main reasons:

The swap body was the first domestic container that appeared at the shipper’s ramp with all features of a common road vehicle. Since road transport is the overwhelming market leader in European freight transport, most logistic systems are designed to meet the basic conditions offered by road transport. Any other transport system would have to overcome this hurdle, i.e. its promoters must request at the shipper’s freight department to install special equipment and organisation to meet the new systems requirements - a task that is, as any experience tells, most difficult. Very often the shipper will tell that he is not even willing to consider a change in his shipping organisation just because the service provider requests it. The swap body had not to overcome this hurdle: A road train equipped with swap bodies appears at the shipper’s ramp in the same manner and shape as a conventional road train - there is nothing specific to be prepared for or organised.

This does not only relate to the physic interface at the ramp. The swap body is a transport unit offered by road operators - the most successful cargo carriers in the last decades. These enterprises could rely on well established business relations between shipper and the transport economy, and they integrated the swap body into their successful strategy to conquer the freight markets.

The second feature that contributed to the success of the swap body system has been the inherent advantages of this engine: The swap body, when used with road trains, is a very useful instrument to promote efficiency in road operation, alone by the possibility to exchange the swap body easily between various road vehicles.

The freight motor industry offered, together with the swap body system, the air suspension for truck and trailer. The air suspension is somewhat more expensive, but it contributes to a smooth run of the road vehicle and its cargo. Most important, it enables a simple swap body exchange without the need for lifting devices or additional personal to serve it. The driver can remove the swap body by a simple operation: He unfolds the standing legs of the swap body until they touch ground. Then he unlocks the twist locks that have fixed the swap body on the chassis. Now he can release air pressure out of the air suspension system: The road chassis will lower some centi-metres and now it is free to drive alone, leaving the swap body free standing on its legs. The take-over of a swap body goes similarly easy: The driver lowers the chassis by its air suspension and manoeuvres it under a swap body standing free on its legs. This operation is facilitated by a guidance tunnel in the bottom construction of the swap body that guides the truck and swap body assembly into the exact position.

When the swap body standardisation was completed, many operators changed to the system chassis + standard swap body and were able to exchange such units freely within their fleet and between partners. This grants, even in pure road operation, a wide set of organisational advantages:

· If the shipper needs more time for loading and discharging at the ramp, the road operator can leave the swap body on its standing legs at the ramp of the shipper while the vehicle and its driver is available for other activities.

· Swap bodies enable the establishment of a relay system: On a north to south run, the driver stops at an intermediate place to meet his colleague who drives, in the same night, the south to north run. They exchange their set of swap bodies and return to their home base. So, each driver will be at home after his shift, driving all the way with the motor vehicle he is responsible for. Drivers welcome this working scheme, and the operator saves costs for overnight stay of drivers.

· Swap bodies can easily be exchanged between long distance operation and local pick-up and delivery. In less than truck load business, the forwarder can set the swap body on a truck to pick up some consignments. Then the swap body will be set down on its legs at one specific ramp position of the forwarders cargo assembly

completely loaded it will be taken over by a long distance road vehicle or by combined transport for the main course. Local deliveries in the arrival area can be organised in a similar manner.

· Swap bodies will facilitate downtown delivery. Many downtown areas do not permit access to large road vehicles and to road trains. So, the driver can un-couple the trailer with the second swap body at a freight station in the outside area of the town and deliver, this time as a single truck, the first swap body at its destination. Afterwards he returns, picks up the second swap body, and drives again downtown for the second delivery.

The various combinations and separations that the swap body system granted to road operation led to a development that, in the end, the vast majority of road operators in Central Europe, when purchasing a road train, ordered it in the version „swap body + chassis“ - even if it was slightly more expensive than a rigid truck + rigid box trailer. The savings that could be achieved through the increased flexibility would easily offset the additional purchase costs of the swap body system.

So, the road transport industry, without needing any additional incentive, equipped its fleet with standard swap bodies, even if they never intended to participate in combined transport. But they were fully equipped for such a change at the very moment when the intermodal carriers would offer them interesting line haul services.

This history of swap bodies as the most successful domestic containers in Europe is limited to class C swap bodies , i.e. the 7 + m long type that normally is carried by road trains. The road carriers that have based their operations on semi-trailers hesitate to alter their transport system into a combination „platform trailer + swap body“. This is caused by the reason that the combination truck + semi-trailer offers practically the same flexibility as the swap body for road train: the separation of the costly motor engine part and driver from the cheap cargo carrying device. A further separation of the semi-trailer into a platform chassis and swap body does by far not generate the same amount of additional flexibility as the separation of road trains into chassis and swap bodies. Furthermore, the class A swap body, i. e. the 13,6 m long box for semi-trailer, cannot be that easily exchanged as the class C swap body because the long and heavy unit cannot be set on standing legs for interchange. All interchanges between one chassis and another (road/road) and all intermdoal interchange operations (e. g. road/rail) need a lifting device with some 34 t lifting capacity. So, there is practically no incentive to overcome the additional investment costs and the potential loss of payload when separating the road vehicle in platform chassis + class A swap body.

In the end the European road vehicle market shows a clear segmentation:

· Many long distance carriers prefer truck and semi-trailer combinations and remain outside combined transport .

· Other operators, mainly those in the less than truck load business, prefer road trains, and very often purchase these road trains as a combination platform truck + platform trailer + 2 class C swap bodies. Most of these

· Some forwarders operating into countries with clear dominance of semi-trailer in road transport have purchased class A swap bodies and hire local drayage capacity from carriers that own platform chassis. These class A swap bodies are mainly operated in combined transport.