Citation

Willumsen LG, Kay W, Ghosh A. Transp. Plann. Tech. 1988; 12(1): 23-37.

Copyright

(Copyright © 1988, Informa - Taylor and Francis Group)

DOI

10.1080/03081068808717357

PMID

unavailable

Abstract

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 intervention; under the first one the software designs the smallest roundabout capable of coping well with traffic demand. The user intervention mode allows the engineer to override the automatic design features and use the package as an (intelligent) electronic drawing board coupled with a roundabout performance calculator. Later sections provide details of the simple optimisation procedures developed and describe our program for further research in this area. An example is discussed in some detail. The package was developed on a PERQ1 computer under PNX and using the C language and the GKS graphical kernel system. The programs have already been used by two British consulting firms to design roundabouts in a much shorter time than possible with manual methods.