00396832

Component

http://onlinepubs.trb.org...s/trr/1984/971/971-004.pdf

https://scholar.google.co...anis&publication_year=1984

The conceptual bases of unsignalized intersection capacity procedures from the Swedish Capacity Manual and from the Interim U.S. Capacity Manual are compared, and the procedures are evaluated with field data from four intersections in the Chicago, Illinois, region. The Swedish method, based on principles of queueing theory and using parameters reflecting Swedish conditions, grossly overestimated capacity and underestimated delay. The empirically based U.S. method substantially underestimated capacity, resulting in level of service values that were approximately one level of service too low. Causes of the poor estimation included critical gaps that were too small in the Swedish method and too large in the U.S. method and inappropriate definitions of dominant volumes. Based on the conceptual and empirical comparisons, critical gaps were revised and dominant volumes were redefined in both methods. Evaluations of these revised procedures revealed much closer correspondence to field-measured values for capacity and delay. With revised critical gaps, the interim U.S. method appears to correspond fairly well with field data. The Swedish method, however, contained errors in capacity and delay estimates that were traced to probable differences in driver performance and traffic conditions in Sweden and in the United States. Preliminary tests of the Swedish delay model indicate that it can provide very accurate delay estimates if it is revised to reflect U.S. drivers and driving conditions.

Publication of this paper sponsored by Committee on Highway Capacity and Quality of Service. 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

00452357

HS-038 730

pp 21-31

1984

Transportation Research Record

0309037530

Print

Figures (3) ; References (19) ; Tables (8)

Accuracy; Highway capacity; Innovation; Queuing theory; Traffic delays; Unsignalized intersections

Highways; Operations and Traffic Management; I71: Traffic Theory

HSL, TRIS, TRB

Jan 31 1986 12:00AM

• ANOTHER LOOK AT STORAGE REQUIREMENTS FOR BANK DRIVE-IN FACILITIES
• AUTOMATED COLLECTION OF VEHICULAR DELAY DATA AT INTERSECTIONS
• CAPACITY, SPEED, AND PLATOONING VEHICLE EQUIVALENTS FOR TWO-LANE RURAL HIGHWAYS (DISCUSSION ANDD CLOSURE)
• COMPUTER SIMULATION TO COMPARE FREEWAY IMPROVEMENTS (ABRIDGMENT)
• DEVELOPMENT AND APPLICATION OF A MACROSCOPIC MODEL FOR RURAL HIGHWAYS
• DISCONTINUITY IN EQUILIBRIUM FREEWAY TRAFFIC FLOW
• DYNAMIC FREEWAY SIMULATION PROGRAM FOR PERSONAL COMPUTERS
• EVALUATING CAPACITIES OF ONE-LANE ROADS WITH TURNOUTS
• INVESTIGATION OF NETWORK-LEVEL TRAFFIC FLOW RELATIONSHIPS: SOME SIMULATION RESULTS
• LEFT-TURN EQUIVALENCIES FOR OPPOSED, SHARED, LEFT-TURN LANES
• LEVEL OF SERVICE CONCEPTS: DEVELOPMENT, PHILOSOPHIES, AND IMPLICATIONS
• PASSENGER CAR EQUIVALENTS FOR UNINTERRUPTED FLOW: REVISION OF CIRCULAR 212 VALUES
• ROLE OF ADAPTIVE DISCRETIZATION IN A FREEWAY SIMULATION MODEL
• SIGNALIZED INTERSECTION DELAY MODELS--A PRIMER FOR THE UNINITIATED
• SIMULATION OF TRAFFIC PERFORMANCE, VEHICLE EMISSIONS, AND FUEL CONSUMPTION AT INTERSECTIONS: THE TEXAS-II MODEL
• SIMULATION STUDY OF GUIDELINES FOR RURAL ROAD IMPROVEMENTS
• USE OF THE NCHRP SIGNALIZED INTERSECTION CAPACITY METHOD--A SOUTH AFRICAN EXPERIENCE
• VEHICLE-DETECTOR INTERACTIONS AND ANALYSIS OF TRAFFIC-ACTUATED SIGNAL CONTROLS