TRANSPORT Minister Gavin Strang yesterday launched a new Piggyback rail freight service in Glasgow, to get more long-distance lorries off the roads.

The trailers of articulated lorries will be loaded on to trains of special railway wagons that will shuttle them rapidly from central Scotland to London.

Travelling at up to 75 miles per hour, the overnight freight trains will complete the 400-mile journey faster than a lorry charging down the motorways, with fast and simple loading and off-loading of trailers at each end.

The service is designed to take freight from the roads without losing the speed and convenience of door-to-door delivery by truck. But the system has limitations at present, as low bridges and tunnels on the West Coast mainline mean not every kind of trailer can be carried.

English Welsh & Scottish Railways, which carries most of Britain's rail freight, will inaugurate the first regular Piggyback service between London and Scotland at the end of June, on behalf of Parcelforce.

The parcel delivery company will load four truck trailers on to a set of special flat-bed wagons at the Eurocentral road/rail terminal at Mossend, Lanarkshire, for transportation to Wembley, every night. Somewhere near Preston, it will pass another carrying a similar cargo north.

Britain's other main rail freight company, Freightliner, is planning to start a similar service next month between Tilbury and Liverpool.

To begin with, both services will be constrained by a shortage of specialist flatbed rail wagons to carry road trailers. But English Welsh & Scottish has ordered 20 more - due for delivery early next year. Freightliner and Railtrack are also investing in similar wagons.

The new services from London to Scotland and Merseyside are being launched under the auspices of the Piggyback Consortium, which groups haulage firms, train operators, rail wagon builders, port authorities, shipping companies and transport pressure groups sharing a common interest in transferring more road freight on to rail.

It sees market potential for piggybacking to save the equivalent of 242,000 long-distance journeys by truck each year - rising to 400,000 in 10 years as the headroom on trunk railway lines improves, enabling trains to carry bigger trailers.

Strang, inaugurating the service at Hillington, on the south side of Glasgow, at the regional depot of Russell, one of the haulage firms closely involved in the road to rail project, said: ''It is essential to our national economic well-being that there is efficient movement of freight and this project contributes strongly to our aim of getting more freight on to the railways.

''This project seems to me to epitomise the virtues of integrated transport. It allows the customer to have the best of both worlds - local transport flexibility with greater certainty in transporting goods over distance,'' he added.