If made law, they would allow hauliers to drive lorries as heavy as 44 tonnes - six tonnes more than the present limit - before the turn of the century.
A Department of Transport consultation document proposes allowing lorries of up to 40 tonnes for general use in line with European law and 44 tonnes for so-called "piggyback" joint road/rail operations.
At present, these heaviest lorries are only allowed for specific journeys involving containers to and from rail routes.
Most controversially, the proposals seeks comments on the idea of allowing 44-tonne lorries for general use by January 1999, or alternatively 2001.
The Roads minister, John Watts, indicated his support yesterday by claiming that the use of the higher-weight lorries on six axles was more "road friendly" than using 40-tonne vehicles on just five axles. "They would also be no noisier and have the same stopping distance as 38-tonne vehicles."
The theory used by department officials and the road freight lobby is that heavier lorries, which can carry more goods, could reduce the total number of vehicles on the road by 6,500. Mr Watts also stressed that heavier lorries did not mean bigger lorries.
However, Lynn Sloman, assistant director of the lobby group Transport 2000 dismissed the Government's arguments as "atrociously simplistic".
She said the net effect of allowing the larger tonnage would be to increase the overall use of roads to carry heavy freight as firms found it more cost efficient than the rail network. "If the Government allows heavier lorries it will be giving a direct subsidy to road haulage, which will be used to add to lorry mileage by centralising distribution still further."
After the last increase in lorry weights to 38 tonnes in 1983, lorry mileage had gone up by 30 per cent and freight mileage risen by more than 40 per cent, she said.
Critics claim that apart from their environmental impact, lorries are proportionately eight times more likely to be involved in a fatal accident than cars.
The Freight Transport Association yesterday gave a mixed reaction to news of the consultation. A spokesman, Adam Wurf, said: "We are pleased that this issue is back on the agenda again."
The organisation believes that collectively, 44-tonne vehicles would save more than 300 million litres of fuel a year and would reduce congestion. They would also save the freight industry about pounds 300m a year - a drop of nearly 8 per cent on the cost of operating the present heaviest vehicles.
However, Mr Wurf said they were dismayed that the plans were only at consultation level, with no clear sign of when they would be implemented, at a time when the industry needed to be able to plan for the future.
Mr Watts said yesterday it was "possible" that once the consultation was completed in the New Year, laws could come in before the general election. But critics fear that ministers are trying to avoid antagonising either the road or the environmental lobbies by making capital out of consulting now, but delaying any unpopular decision until after the poll.Reuse content