Intersections without Traffic Signals II: Proceedings of an International Workshop, 18–19 July, 1991 in Bochum, Germany PDF
Preview Intersections without Traffic Signals II: Proceedings of an International Workshop, 18–19 July, 1991 in Bochum, Germany
Werner Brilon (Editor) Intersections without Traffic Signals II Proceedings of an International Workshop 18-19 July, 1991 in Bochum, Germany With 163 Figures Springer-Verlag Berlin Heidelberg NewY ork London Paris Tokyo Hong Kong Barcelona Budapest Prof. Dr.-lng. Werner Brilon Lehrstuhl fUr Verkehrswesen Ruhr-Universitat Bochum UniversitatsstraBe 150 4630 Bochum This workshop was made possible by the generous support of the following organisations: Deutsche Forschungsgemeinschaft (German Council for Research) Minister fUr Stadtentwicklung und Verkehr des Landes Nordrhein-Westfalen ISBN -13: 978-3-642-84539-0 e-ISBN -13: 978-3-642-84537-6 DOl: 10.1007/978-3-642-84537-6 This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, re-use of illustrations, recitation, broad casting, reproduction on microfilms or in other ways, and storage in data banks. Duplication of this publication or parts thereof is only permitted under the provision of the German Copyright Law of September9, 1965, in its current version and a copyright fee must always be paid. Violations fall under the prosecution act of the German Copyright Law. © Springer-Verlag Berlin, Heidelberg 1991 Softcover reprint of the hardcover 1st edition 1991 The use of registered names, trademarks,etc.in this publication does not imply,even in the absence ofa specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Typesetting: Camera ready by author 61/3020-543210 - Printed on acid-free paper Preface In March 1988, an international workshop on intersections without traffic signals was held at the Ruhr-University in Bochum, Germany. The proceedings of this workshop were published by Springer 1). The workshop was performed in a very harmonious atmosphere, which stimulated the experts from different countries to communicate and exchange their ideas and experiences. The presentations and the written contributions documented the present state of technical solutions for design and engineering of unsi gnalized intersections both regarding scientific research and practical applications. Moreover, numerous unsolved problems were identified. Thus, the 1988 workshop stimulated new developments in the field of unsignalized inter sections in several countries. In the meantime, these investigations have lead to a remarkable progress. For example in Germany a new guideline for unsignalized cross intersections and T-junctions has been finished and is going to be introduced in 1991. New results on roundabout capacity have been worked out as well. Many particularly important developments were made in foreign countries. Especially in the United States, an increasing interest in this subject can be observed. In the annual meetings of the TRB, this item received great attention. Many research institutes in North America have concentrated their activities on that point. A new TRB-circular concerning unsignalized intersections is going to be published. It will contain a new procedure for four-way-stop-control intersections, which seems to be a special feature of North American traffic engineering. However, new results from the US for two-way-stop control intersections are available as well. Especially in the field of roundabouts - or "rotaries", which seems to be the American term -some progress has been made. Roundabouts are on the advance worldwide. Many countries like Australia, France, Norway, Sweden, Switzerland and Germany are in creasingly using roundabouts as an intersection design which bears comparison with other solutions or which is even more advantageous. This increasing use of roundabouts induces a great variety of new experiences both in the field of intersection capacity and with intersection design and traffic safety. 1) W. Brilon (editor): Intersections Without Traffic Signals. Springer Verlag, 1988, ISBN 3-540-18890-8. VI The progress made between 1988 and today supported the idea of holding a second international workshop on unsignalized intersections. This was also confirmed in discus sions with experts from different countries. The Ruhr-University Bochum will again host this event. The fact that a second workshop is held on the same item at the same place, however, should not establish this event as another continuous series of traffic enginee ring congresses. The general situation in the theory of capacity for unsignalized intersections is still cha racterized by the discussion between gap-acceptance theory and empirical regression models. Both still have their own specific advantages and drawbacks. Therefore, both approaches are in use in different countries. It can be stated that the more theoretically based gap-acceptance theory is still applied for cross-intersections and T-junctions in many countries. As many of the contributions to the workshop point out, this theory is still capable of further improvement. One reason for the use of this fundamental theory may be that it provides a better understanding of individual operations and of the hier archy of traffic streams at such intersections. Thus, it enables an extrapolation of solu tions for traffic flows which have not been observed in reality. The regression theory, however, is also more and more observed with interest outside Great Britain, which has the longest experience with this general approach. Presumably -with few exceptions- it has occupied nearly the whole field of roundabout capacity calculations. The reason for this could be that this approach is more suitable for handling driver behaviour which dif fers from pure gap-acceptance patterns like gap-forcing and priority reversal. The idea that critical gaps and move-up times could depend on the traffic load of the intersection could become an approach to overcome these differences. To detect these kinds of effects, the precise evaluation of critical gaps from traffic obser vations could again become a field requiring increasing attention in the future. This point of discussion brings us back to the basic fact that modelling in traffic enginee ring always contains two aspects: the mathematical construction and solution of the model on one side and the implementation of driver behaviour on the other side. For further improvements of traffic engineering methods, especially the aspects of a more sensitive and realistic modelling of driver behaviour by the models as well as by the parameters being included into the models will become increasingly important. Moreover, some of the differences between the approaches and the experiences from various countries could be due to basic differences in behaviour of road users. Beyond intersection capacity estimations, however, the improved safety of traffic opera tions on our roads is the most essential task for traffic engineers. This is especially true for the decisions on control strategies and on types of intersection design. The contribu- VII tions to the workshop consider this aspect as well. Unfortunately, due to the closely packed timetable, only one contribution which concentrates on safety could be included, although two more interesting papers on this issue had been proposed. However, almost every contribution pays special attention to the aspect of traffic operation safety, which is an argument for more integrated considerations of design, capacity and traffic safety. For the preparation of the workshop, a number of papers from several countries have been invited to give a current overview of the whole subject considering the respective circumstances of the specific countries. In addition, a call for papers was sent out in Sep tember 1990, resulting in an interesting variety of abstracts proposed for the workshop. From these, a series of 15 papers has been selected by the advisory board (Prof. Keller, Munich; Prof. Retzko, Darmstadt and Prof. Brilon, Bochum). The work of this group and especially the excellent discipline of the authors regarding the quite narrow sche dule for the preparation of the manuscripts should particularly be commended, since it enables the presentation of the proceedings just in time for the workshop. The authors and the editor hope that this publication and the workshop itself will con tribute to continued efforts within the community of traffic engineering researchers and practicians. Moreover, this event should accelerate the international exchange of new ideas and generate new impulses for further developments on this specific item of un signalized intersections as one part of the whole field of traffic engineering. Bochurn, April 1991 Prof. Dr.-Ing. W. Brilon Contents Capacity and Safety of Roundabouts in Germany Stuwe. B ......................................................................................................... 1 Polish Guidelines for Capacity Analysis of Priority Intersections Tracz, M ...................................................................................................... 13 Aspects of the Calculation of Unsignalized Intersections Schnabel, W. ............................................................................................... 27 Roundabouts in Switzerland -Recent Experiences, Capacity, Swiss Roundabout Guide Simon, M ..................................................................................................... 41 Experiences with Intersections without Traffic Signals in Great Britain Peirce, J ....................................................................................................... 53 Calculation Procedures for German Practice: Intersections without Traffic Signals Brilon, W./Grossmann, M ....................................................................... 62 Modular System for Traffic Simulation at Intersections and in Networks Friedrich, B./Ploss, G ............................................................................... 83 A Comparative Study of Roundabout Capacity Procedures Hakkert, A.S./Mahalel, D./A sante, SA. .............................................. 93 Roundabouts and Road Safety Alphand, F./Noelle, U./Guichet, B. .................................................... 107 Evolution of Design Rilles for Urban Roundabouts in France Alphand, F./Noelle, U./Guichet, B. .................................................... 126 IX Case Study. Performance Effects of Changing a Traffic Signal Intersection to Roundabout Hoglund, P ................................................................................................ 141 A Microscopic Simulation Model of Roundabout Entry Operations Tan, Jian-an .............................................................................................. 159 A General Capacity Formula for Unsignalized Intersections Wegmann, H ............................................................................................. 177 Intersections without Traffic Signals -Swedish Experiences on Capacity and Safety Bergh, T ..................................................................................................... 192 A Strategy to Optimise the Geometric Design of Isolated Priority Junctions Borzym. I./Silcock, J.P. ........................................................................... 214 Hungarian Measurin~ Results: Observations and Methods for Calculating Capacity at Intersections without Traffic Signals Benyei, A./Fi, I. ....... :. .............................................................................. 226 Unsignalized Intersections and Roundabouts in Australia: Recent Developments Troutbeck, R ............................................................................................ 238 Gap Acceptance and Risk Analysis at Unsignalized Intersections Lassarre, S./Lejeune, P .......................................................................... 258 Use, Design and Safety of Small Roundabouts in Norway Seim, K ..................................................................................................... 270 x Accident Prediction Models for Unsignalized and Signalized Intersections Huang, Y./May, A .................................................................................. 282 Gap Acceptance, Wait Time, and Risk Aversion at Unsignalized Intersections Fricker, 1./Gutierrez, M./Moffett, D .................................................. .297 Simulation of Multilane Stop-Controlled T-Intersections by KNOSIMO in Canada Chan, P./Teply, S. ................................................................................... .308 Estimating High and Low Flow Rates at Unsignalized Intersections Virkler, M./Madsen, R./Sutton, 1. ...................................................... .320 Empirical Models for Estimating Capacity and Delay at Stop-Controlled Intersections Kyte, M./Zegeer, 1./Lall, B ................................................................... 335 Capacity and Safety of Roundabouts - German Results Birgit Stuwe Lehrstuhl flir Verkehrswesen, Ruhr-University, Bochum, Germany SUMMARY The objective of the research project described in this paper was to develop a formula for calculating the capacity of roundabouts. These formulae were developed by use of an empirical procedure and regression techniques. Therefore, traffic flow at several roundabouts was observed and recorded by video equipment. Based on the assumption that the entry flow was saturated, traffic flow of entering and cirulating vehicles were analysed and counted in 1-minute intervals. Based on this data samples, a provisorial formula has been developed for the prediction of roundabout capaClty. Four different curves have been specified according to dependance upon the number of lanes in the circular and the entry. These curves are used in practice for capacity calculations of roundabouts in Germany. Furthermore, an investigation of accident data is described in this paper. In particular the accident research confirmed considerable increase in traffic safety at roundabouts compared to signalised or unsignalised intersections. Accident severity is reduced at roundabouts. It was found that the roundabout is a good solution to increase traffic safety. INTRODUCTION Places and sites of circular shape have been an instrument of city and town planning since the Middle ages and especially during the Renaissance. Circular places were suited where it was worth to emphasize the significance of a place. It was an idea of Henard to implement one-way traffic on such greater places and thus the Place de l'Etoile in Paris was the first roundabout. Also in Germany roundabouts have been constructed especially during the 30ies and 50ies. Later on, many of the existing roundabouts in Germany were rebuilt into junctions with traffic signals. Roundabouts were not paid attention to any more -especially due to a lack of suitable capacity estimations, of bad accident experience and also because of a misinterpretation of the existing rules. Traffic engineers assumed that they would have to treat the entries like waving areas. The length of the waving area determines the capacity of such facilities. So the capacity increases with the length, which means that
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