The importance of energy for transport was recognised in Report No. 1 published by The Watt Committee on Energy in 1977.Two features of transport energy use are its magnitude (approximately 22% of the UK total) and its vulnerability to oilsupplies (nearly 50% of our oil supply). There have been several excellent conferences elsewhere since then on newtechnology and the future designs of aircraft, ships and railway trains but there seemed a need to consider all transport modestogether. In assessing substitution of energy sources there is a tendency also to consider substitution of transport modes, butthis is a complex matter and such substitutions will be slow and generally costly. There are historic instances of such changes, e.g. from sail to steam at sea in the 19th Century, from coal to oil on the railways in the 1950s and from petrol enginedaircraft to kerosene powered jets in the 50s and 60s. Such changes take place over a time span of decades. Some transportvehicles have a normal replacement time of 30 years, a few longer still, hence it is a vital matter to match any major transportresponse to future energy changes to the appropriate time scale