WE KNOW IT'S GOOD, BUT JUST HOW GOOD IS IT?

Capacities at traffic signal controlled intersections may be readily calculated by use of established empirical equations. However, auto-adaptive systems such as Microprocessor Optimised Vehicle Actuation (MOVA) respond dynamically to vehicle demands that make the prediction of their performance very difficult. Indeed, there is currently no analytical technique available for predicting in advance the extent of the improvement at any site, save for expensive and time consuming micro-simulation techniques or particularly vehicle detector occupancy studies. To overcome this, an examination of the vehicle discharge rates and hence saturation flow rate was undertaken that aimed to produce factors that could be applied to current traffic signal calculations for the estimation of MOVA. The saturation flow rate was particularly used because it is one of the principal factors that govern traffic signal capacity. (A)