00638678

Component

http://onlinepubs.trb.org...trr/1993/1398/1398-009.pdf

https://scholar.google.co...tuwe&publication_year=1993

Capacity and traffic safety of traffic circles in Germany have been investigated in comprehensive research projects carried out at the Ruhr University Bochum. On the basis of observations of real traffic conditions, formulas for predicting traffic circle capacity under conditions in Germany have been developed. These formulas have been specified in terms of the number of lanes in the circle and in the entry. The capacities of traffic circles measured in Germany appear to be considerably less than the values predicted by English formulas. For German traffic circles, capacity has been measured at between 0.7 and 0.8 of English values. However, there is good agreement between calculations for French and German capacity. The influence of geometric parameters was also investigated. In addition to the number of lanes in the circle and in the entry, geometric parameters turned out to be significant for estimating the capacity of traffic circles. These parameters are inscribed circle diameter, number of traffic circle arms, and distance between exit and entry of the observed arm. Traffic circles in Germany also provide a considerable increase in traffic safety when compared with normal signalized or unsignalized junctions. Before and after investigations at small, single-lane traffic circles showed that traffic circles have a lower severity of accidents, whereas the number of accidents stayed almost the same. Experience with existing traffic circles resulted in some significant recommendations for the design of traffic circles. Using the suggested design criteria, good experience has been shown in several cases and has led to a rapid increase in the number of new single-lane traffic circles. Public opinion also favors traffic circles.

This paper appears in Transportation Research Record No. 1398, Traffic Flow and Highway Capacity. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

01403239

English

p. 61-67

1993

Transportation Research Record

0309054672

Figures (2) ; References (26) ; Tables (4)

Before and after studies; Crash severity; Design; Diameter; Geometric design; Highway capacity; Single lane traffic; Traffic circles; Traffic lanes; Traffic safety

Design criteria

Germany

Germany

Design; Highways; Operations and Traffic Management; Planning and Forecasting; Safety and Human Factors; I21: Planning of Transport Infrastructure; I71: Traffic Theory; I82: Accidents and Transport Infrastructure

TRIS, TRB, ATRI

Oct 26 1993 12:00AM

• CAPACITY AND DESIGN OF TRAFFIC CIRCLES IN AUSTRALIA
• COMPARISON OF PERFORMANCE OF TWOPAS AND TRARR MODELS WHEN SIMULATING TRAFFIC ON TWO-LANE HIGHWAYS WITH LOW DESIGN SPEEDS
• DEVELOPMENT AND APPLICATION OF A METHODOLOGY EMPLOYING SIMULATION TO EVALUATE CONGESTION AT SCHOOL LOCATIONS
• EFFECT OF HEAVY VEHICLES AT AUSTRALIAN TRAFFIC CIRCLES AND UNSIGNALIZED INTERSECTIONS
• EFFECTS OF LOCATION ON CONGESTED-REGIME FLOW-CONCENTRATION RELATIONSHIPS FOR FREEWAYS
• EFFECTS OF U-TURNS ON LEFT-TURN SATURATION FLOW RATES
• GRAPHICAL COMPARISON OF PREDICTIONS FOR SPEED GIVEN BY CATASTROPHE THEORY AND SOME CLASSIC MODELS
• LEFT-TURN ADJUSTMENT FOR PERMITTED TURNS FROM SHARED LANE GROUPS: ANOTHER LOOK
• LOGNORMAL DISTRIBUTION FOR HIGH TRAFFIC FLOWS
• METHODOLOGY TO ASSESS LEVEL OF SERVICE ON US-1 IN THE FLORIDA KEYS
• OVERFLOW DELAY AT A SIGNALIZED INTERSECTION APPROACH INFLUENCED BY AN UPSTREAM SIGNAL: AN ANALYTICAL INVESTIGATION
• PROBABILITY OF OVERLOAD AT SIGNALIZED INTERSECTIONS
• REVISED QUEUEING MODEL OF DELAY AT ALL-WAY STOP-CONTROLLED INTERSECTIONS
• SIGNAL DESIGN FOR CONGESTED NETWORKS BASED ON METERING
• SOME OBSERVATIONS ON SPEED-FLOW AND FLOW-OCCUPANCY RELATIONSHIPS UNDER CONGESTED CONDITIONS
• STUDY OF FREEWAY BOTTLENECKS IN TEXAS
• SUGGESTED PROCEDURES FOR ANALYZING FREEWAY WEAVING SECTIONS