Operational Analysis of Collector-distributor Systems
Kansas Department of Transportation, 1993 - Express highways - 363 pages
This 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.
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A Typical Freeway System
THE SKELETON AND THE SYNOPSIS
FIGURE 2 The Flow Chart of The Analysis Procedure
21 other sections not shown
70 BUSES AASHTO acceleration lane ADJUSTMENT FACTORS PERCENTAGE ANALYSIS DOWNSTREAM RAMP analysis procedure ANALYSIS RAMP CHARACTERISTICS at-grade intersection auxiliary lane Basic Segments C-D ROADS ANALYST cloverleaf interchange CLOVERLEAF WITHOUT C-D collector-distributor roads COMBINATIONS OF WEAVE Conflict Area CONSIDERED AS TRUCKS DATE OF ANALYSIS DESIGN SPEED mph diamond interchange diverge volume DOWNSTREAM RAMP FREEWAY Downstream Reference Location FREEWAY RAMP RAMP FRONTAGE ROAD FULL CLOVERLEAF grade separations Highway Capacity Manual HIGHWAY DESIGN SPEED interchange spacing intersection JANUARY 31 LANE RAMP lane-changing LANES ON FREEWAY Leisch level of service merge volume number of lanes on-ramp one-lane operational analysis pcph PEAK HOUR FACTOR PERCENTAGE OF TRUCKS RAMP ANALYSIS RESULTS RAMP FREEWAY RAMP ramp junction RECREATIONAL VEHICLES Reference Location ft roadway Service Graph Simulated Subsection TEST SEVERAL COMBINATIONS traffic stream traffic volumes UPSTREAM ANALYSIS DOWNSTREAM Washington D.C. WEAVE VOLU weaving area Weaving Flow Rates weaving length weaving section weaving speeds weaving vehicles