Abstract
The control of traffic is frequently performed with traffic signals. In urban areas they are often coordinated, traditionally the time plans are calculated manually. However many comparisons show that the urban road network can be used more effectively in terms of road user costs etc., if computerised methods are used. To avoid loss in effectiveness the time- plans should be updated frequently. Analysis shows that loss can be estimated at three per cent per year. Against this background the strategy "Automatic updating of TRANSYT timeplans, AUT", has been developed.