COMPUTER ASSISTED DESIGN OF THE GEOMETRY OF ROUNDABOUTS

The development of low cost/high performance computers provides an excellent opportunity to develop better techniques for junction design. The Transport and Road Research Laboratory has developed ARCADY, a program to estimate the performance of a particular roundabout layout. In order to use ARCADY the traffic engineer has either to produce a preliminary layout drawing and extract the required geometric input to the program or make an educated guess at suitable parameters and if satisfactory, attempt to fit a layout to them. In either case a considerable amount of trial and error is likely to be involved. This paper describes in some detail a software package developed at University College London performing the task above wholly in the computer and with a minimum of user intervention. The paper describes the background to this research project, outlines current manual techniques for roundabout design and gives an overview of the software. Two modes of operation are available: automatic design and user in...