Traffic Network Study Tool

Direct CORSIM Optimization, CORSIM Post-Processing

TRANSYT-7F offers CORSIM post-processing, such that the engineer can summarize results from one or more CORSIM runs (with varying random number seeds).  Following a CORSIM post-processing run, TRANSYT-7F produces a summary text report that contains NETSIM link results, NETSIM node results, and CORSIM network-wide results.  TRANSYT-7F can also provide a one-page formatted report for NETSIM intersections.  The summary text report and formatted report both provide intersection-wide control delay and level of service.  The formatted report also provides approach-specific control delay and level of service.  The Map View can also be used to graphically display NETSIM control delay and level of service.  The interactive time-space diagram can be used to observe and design bandwidth in NETSIM.

TRANSYT-7F also offers "direct" CORSIM optimization (also known as "microscopic" optimization) of cycle length, splits, and offsets, using the genetic algorithm.  With direct CORSIM optimization, TRANSYT-7F applies the genetic algorithm to supply timing plan candidates, and CORSIM evaluates them through its own simulation.  The end result is a new copy of the original CORSIM input (*.TRF) file containing the optimized timing plan, plus the availability of TRAFVU animation for the optimized timing plan.  TRANSYT-7F will minimize NETSIM control delay by default, but the user can choose among nine different CORSIM MOEs to be used as the optimization objective function.

Because direct CORSIM optimization is accomplished via genetic algorithm, this ensures that the user's original timing plan will be improved upon, assuming that a better timing plan exists.  In addition, direct CORSIM optimization can be easily applied by anyone, because there is no learning curve.  Simply launch TRANSYT-7F, load any TRF file, select one of the nine available optimization objective functions, and click on "Run".  This alone achieves a better CORSIM timing plan than any other program or process.  Once the user gains experience with choosing non-default genetic algorithm parameters (e.g., mutation probability, population size, etc.), the optimization process can become even more efficient and effective.

All pre-timed, fully-actuated, and semi-actuated intersections in CORSIM can be optimized directly.  The current version of TRANSYT-7F does not support direct CORSIM phasing sequence optimization, although this could be accomplished by macroscopic (TRANSYT-based) optimization.  If an optimized phasing sequence is coded or exported into a TRF file, the overall timing plan could then be further improved via direct CORSIM optimization of cycle length, splits, and offsets.  Note that direct CORSIM optimization may not be practical for large TRF files, due to the CPU running time required for microscopic simulation.