NOAH is a computer program designed to optimise the horizontal and vertical alignments of a new road simultaneously. The development of NOAH has now reached a stage at which the program is suitable for widespread use on actual highway design, and has been tested on three widely differing road schemes, a by-pass for a market town in Great Britain. The result showed that the program can be used to obtained an alignment which minimises the economic return on the capital investment. The tests have shown that NOAH can be of value to highway engineers and that use of the program can lead to a reduction in overall cost, improved benefits and reduced design effort. Also, a far more detailed study of alternative alignments is possible than with conventional manual methods.