road design with level, standard - width carriageways and uniform side slopes 
etc. The whole operation is a primitive form of optimisation - primitive 
because the computer does not select the best of all possible routes but merely 
the best of those suggested by the engineer. More sophisticated routines have 
been tried, principally in the U, 5. A, and as long as ten years ago, but although 
widely publicised at the time they were not well received by the industry as a 
whole. Eventually, true optimisation routines will be developed which find more | 
general acceptance, of this there is no doubt, but there are many difficulties. 
A suitable program would have tc take into account gradients, sight limits, 
curvature, land values, construction standards, operating costs and a host of 
imponderables which almost defy evaluation. Without question, it would be a e & 
most complicated program, expensive in use and requiring a large, very fast 
computer. Study of the problem continues at many centres, including the Road 
Research Laboratory of the U, K, Ministry of Transport and the University of 
London Institute of Science, who report that some progress has been made, 
though limited at present to optimisation of the vertical profile for a horizontally 
fixed route. It is a fascinating subject which will absorb many man-years of 
research before a complete solution is found. 
Design stage 
Design stage involves consideration of the detailed design of the road 
and ends with the issue of tender documents. e e 
The route established at scheme stage may have been legally fixed but 
since in all probability it is defined only as a thick line on a fairly small scale 
map, it remains possible to modify it further by movements of up to perhaps | 
15 or 20 metres laterally. | 
In order to make these refinements, and also to provide accurate data 
for the Bill of Quantities, a more detailed survey is required over the now 
narrow band of interest. The new survey will be at large scale and include 
either cross sections or a fine-mesh DTM with levels accurate to + 0.1 metre.