Operational Analysis of Collector - Distributor Systems: Final ReportThis document consists of three sections, each with its own table of contents and independent numbering. Part I, Operational Analysis of Collector-Distributor Systems, develops a procedure for capacity analysis of Collector-Distributor (C-D) roads between successive interchanges. The description of the capacity analysis procedure generally follows the 1985 Highway Capacity Manual procedures; however, a new procedure developed in July 1990 at the University of California, Berkeley, is used for the weaving sections. There is a completed example of the entire procedure for the existing Roe-Nall and the once-proposed braided ramp systems on I-435 in Johnson County, Kansas. This study also identified problems at the merge/diverge areas of the system as a result of "the concentration of two freeway diverging flows at one off-ramp junction, and the accumulation of two C-D merging flows at one on-ramp junction". Configuration changes such as the addition of an auxiliary lane at the merge location and a second off-ramp between the interchanges for the diverge area, were also analyzed for comparative purposes. Part II, Operational Analysis of the Full Cloverleaf Interchange Equipped with Collector-Distributor Roads, describes the advantages of the C-D interchange, a methodology to analyze the interchange, and some of the problems associated with the analysis. The study demonstrates the analysis procedure and reveals that the merge and diverge points become problem areas of the interchange when C-D roads are added. Therefore, the improvements made by moving the weaving area off the mainline should be compared to the decreased level of service at the merge/diverge areas. The study recommends auxiliary lanes for both the merge and diverge areas when C-D interchanges are being considered. Part III is the Technical Appendix for Part II |
Contents
THE SKELETON AND THE SYNOPSIS | 6 |
PHYSICAL ANALYSIS OF FREEWAY SYSTEM | 12 |
OPERATIONAL ANALYSIS OF FREEWAY SYSTEM | 34 |
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Common terms and phrases
1982 DESIGN POLICY 70 BUSES acceleration lane ADJUSTMENT FACTORS PERCENTAGE ANALYSIS RAMP CHARACTERISTICS ANALYSIS RESULTS TRUCK analysis segments at-grade intersection Auxiliary Lanes BASIC FREEWAY BUSES AND RV'S C-D ROADS ANALYST CHECKPOINT VOLUME cloverleaf interchange CLOVERLEAF WITHOUT C-D COLLECTOR-DISTRIBUTOR ROADS COMBINATIONS OF WEAVE configuration CONSIDERED AS TRUCKS curve DATE OF ANALYSIS DESIGN SPEED mph diamond interchange freeway system FREEWAY TRUCKS RAMP frontage road FULL CLOVERLEAF grade separations Highway Capacity Manual HIGHWAY DESIGN SPEED IDENTIFYING INFORMATION FACILITY INPUT INFORMATION JANUARY 31 LANE RAMP LANES ON FREEWAY level of service LEVEL TERRAIN loop ramps N.A. DISTANCE N.A. RAMP TYPE nonweaving vehicles number of lanes off-ramp on-ramp operational analysis pcph PEAK HOUR FACTOR PERCENTAGE OF TRUCKS POLICY AND CRITERIA RAMP ANALYSIS RESULTS ramp junctions RAMP TYPE N.A.
N.A. RECREATIONAL VEHICLES RV'S ARE CONSIDERED SYS DATE TEST SEVERAL COMBINATIONS TRUCKS N.A. WEAVE VOLU weaving area WEAVING FLOW RATE weaving section weaving speeds weaving vehicles