Civil engineering design methodology is changing as a result of emerging computer hardware and software. Highspeed, interactive, user-friendly systems are more common, whereas formerly batch submission of batch-oriented programs was the only common method. However, a variety of large, complex program packages are still widely used for urban drainage design problems. These packages are usually executed on mainframes with a large memory capacity and high computing speeds; users need a good working knowledge of FORTRAN input requirements and mainframe job control language, especially when the packages are used in a multi-program, multiprocessor environment. Furthermore, long learning times are associated with the implementation and execution of complex packages on batch-oriented mainframes at remote sites.This paper discusses the design of an interactive package of pre- and post-processors to facilitate input data preparation, job execution, output interpretation, and job resubmission in a multi-program, multiprocessor, remote batch environment. The pre-processors create input data files for job execution; the post-processors operate on the output from the simulation package, synthesizing, analyzing, and plotting to accelerate the users' interpretation at their terminals. The important advance in this work is that the original coding for the main, externally supported, batch-oriented package is not altered. Furthermore, local text processing using previously prepared, disc-based outline reports and the post-processor output allows direct production of draft reports.