Ein nutzerorientiertes Verfahren zur Gesamtbewertung des Verkehrsablaufs an lichtsignalisierten Landstraßenknotenpunkten

  • A new procedure to determine a user-oriented level of service of traffic light controlled crossroads

Becher, Thorsten; Steinauer, Bernhard (Thesis advisor)

Aachen : ISAC (2011)
Dissertation / PhD Thesis

In: Aachener Mitteilungen Straßenwesen, Erd- und Tunnelbau 55
Page(s)/Article-Nr.: XXVIII, 248 S. : Ill., graph. Darst., Kt.

Zugl.: Aachen, Techn. Hochsch., Diss., 2011


The dimensioning of road infrastructures has taken place in Germany since 2001 according to the Manual for the Design of Road Infrastructures (HBS) which is modeled after the American Highway Capacity Manual (HCM). Since that time the description of traffic quality in the German technical rules has been based on the principle of level of service (LOS). The traffic quality defined solely according to capacity in the technical rules up until then has undergone a theoretical supplement in its basic principles due to the idea of a user-oriented viewpoint, which means the driver’s point of view. The existing methods for evaluating the design parameters however still show, nine years after being introduced, some weaknesses and gaps, particularly with regard to the driver’s point of view. For example with the current HBS partial elements of intersections, individual stretches of road etc. can only be designed in terms of traffic engineering. Intersections as a whole (all directions and all lanes together) and seen from the driver’s point of view cannot be evaluated at present with the HBS. So together with this dissertation a method was developed for the overall evaluation of a traffic light controlled rural road intersection which contains both a traffic-related and a user-oriented component. The newly developed method is based on a basic analysis which in addition to the description of the fundamental requirements and criteria for the design and evaluation of traffic light installations also considers psychological basic ideas with regard to modeling the circulation of traffic on the human-system level. Of particular significance in this context are the perception and interpretation of traffic situations and the emotions and reactions of the drivers which contribute to the general traffic climate. Subsequently the newly developed method is based on the existing parameters of Chapter 6 of the HBS "Intersections with traffic light installations" and supplements the current quality grade concept for evaluating the individual signal groups of a traffic light installation with a collated, user-oriented evaluation of the whole intersection. Due to the different facets a link was created for this purpose between traffic engineering, sociological and psychological findings which were gained from test series in the traffic laboratory and from real life. For the method evaluation curves to determine dissatisfied drivers and an acceptance rating to establish the tolerance of waiting times were derived through empirical studies and analysed by means of sensibility tests. The evaluation curves were able to show how negative influences on the traffic climate occur when the waiting times at an intersection increase. After only 60 seconds of waiting time over 50% of the drivers are impatient and over 15% even greatly annoyed. With these values the acceptance limit which could be found to range between 60 and 70 seconds at a red traffic light is almost reached. The road categories, the time gaps of the intersecting traffic flow and the position of the intersection in the course of a drive aren’t the decisive parameters for the arising negative emotions, but probably the psychological parameters of the driver himself. In consideration of these findings the method is used to calculate a dissatisfaction index and a user-oriented traffic quality mark for a standard intersection with one or two lanes at the access road. On the basis of the waiting times which occur and the resulting ratings it is possible to make a statement on the level of dissatisfaction of the drivers crossing the intersection. This method for rating user-oriented traffic quality is at present the only method that can evaluate a traffic-light controlled intersection on a rural road from the point of view of the user. This also ultimately enables a more appropriate discussion on the required minimum level of service and at the same a heightened consideration of the quality aspects from the point of view of the road user.