RODEL - AN ALTERNATIVE APPROACH TO ROUNDABOUT DESIGN.

Roundabout design has been traditionally evaluated against geometric and safety standards and by comparing forecast traffic flows with capacity estimates. Designs that fulfil these criteria are normally considered satisfactory. However, the recent development of better equations for estimating capacities, queues and delays, together with the increased availability of computers, now enables the design and evaluation of roundabout layouts to be made in a manner not previously possible. To take advantage of these developments 'RODEL', a computer program for aiding roundabout design, has been developed. The program is fully interactive with simultaneous display of input and output. This enables the design engineer to experiment rapidly with changes in geometry while viewing the immediately displayed changes in queues, delays and delay cost.