Capacity Analysis of Interchange Ramp Terminals Final Report (1997) / Chapter Skim
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APPENDIX F Development of INTERCHANGE Analysis Software
APPENDIX F Development of INTERCHANGE Analysis Software
Pages 333-350
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signalized interchanges within a single standalone software package or using an interface with existing software previously mentioned. The program will adapt the recommended operational analysis procedures developed for intersections and interchanges which was described earlier in section 3.3.2 and shown in Figure Fit.
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EFFECTIVE GREEN MODULE Nominal lost times Turn blockage Queue blockage ~ PDX Model Effective green 1 ' 1 5. CAPACITY ANALYSIS MODULE · Compute lane group capacities · Compute lane group v/c ratios · Identify critical lane groups r 6.
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INTERCHANGE Proceclural Design Analysis performed using existing software packages · Interface HCS PASSER 11, 111 TRANSYT-7F Other Software Analysis Operational analysis as pefforrned by the specific program l Oust Capacity Delay and Speed LOS INTERCHANGE Input Turning movement volumes for one interchange form Type of analysis requested Interchange types to analyze Geometric and Signalization Conditions INTERCHANGE Conversion Analyses · Database conversion algorithm Analysis to be performed using proposed new singl software package · ~ INTERCHANGE Analysis rl Volume Adjustment Module Saturation Flow Rate Module Effective Green Module Capacity Analysis Module Level of Service Module ~ , INTERCHANGE Output Future or existing fuming volumes for chosen interchanges LOS and performance measures for chosen interchange Ranking based on operational performance measures and LOS Figure F-2. Flow diagram of optionalprocedural design for INTERCHANGE.
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The volume adjustment module, saturation flow rate module, effective green module, capacity ar~alysis module, and level of service would all be computed within INTERCHANGE. After perfonn~ng the analysis on each interchange selected, the program could produce outputs displaying performance measures for each selected configuration individually or together for making easy comparisons.
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Any volume datainputinto the penpheralinterchanges automatically gets converted to the core module arid then may be reconverted to arty of the other interchange configurations once selected by the user. The benefit of this structure is that the user only needs to enter the mining movement volumes for one of the peripheral interchange configurations, and the effect of that input is available to all the other interchange forms.
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Possible near-term tasks include coding in parts of the volume adjushnent, saturation flow, effective green, and capacity analysis modules for particular interchange types. The input screens can be programmed to accept additional data such as geometric and signalization conditions.
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~ ~ N / / 500 1 100 1 10 \ 90 100 =D 200 ~ < / Figure F-4. Existing at-grade intersection with future turning movement volumes.
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A small picture of the existing at-grade intersection is shown at the right of the screen, however, any interchange configuration can be chosen as the existing condition to begin entering turning movement volumes. To enter turning movement volumes, the user clicks on the appropriate square in the first column entitled "turning movement volumes." Future versions of the program will allow other information, shown as column headings, to be input.
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i ':: ' -Choose One O ~'an'and ~ nterehange ParcIo ; ParcIa 2- AS Pareto 2-~d BA ~ Palolo 2-~d Be O ParnIa 4-~d ~ ParnIO 4-~d AD O ParcIo 4~d OA O Pareto 4-~.a`d }38 ~ ~'ngle-~oint D 'am 43 Core Intersection ..
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The same volumes that were coded in the input boxes in Figure F-6 are now shown in their respective approaches directly on the picture of the intersection. This enlarged view may be more appropriate for some users since turning movement volumes can be changed within the picture and little contusion exists as to the location of the turning movement volumes.
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Significant fluctuations in performance measures were seen in the parclo 2quad AA design. Very high delays of 36.3 and 30.3 sec/veh were seen on We leD-side intersection's east-bour~d left and west-bound through/right movements respectively, and very low delays of 7.9 sec/veh were experienced on the east-bound through.
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Enlargedpicture of a diamond interchange.
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V/C Analysis for Left and Right-Side Intersections Using PASSER I! ||Interchange type | Is Left-Side Diamond *
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To begin the analysis, the user clicks the "lane analysis" button shown at right in Figure F-9. In the lane analysis screen, shown in Figure F-IO, the user cart have the program immediately perform a lane analysis based on the turning movement volumes by clicking the "calculate"button or the user can evaluate an existing lane configuration.
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P=' PI' P='~ 4 Pent 4 .~0Pr Figure Few. Enlarged picture of a diamond interchange with lane analysis results.
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Enlarged picture of a diamond interchange with f nal lane analysis.
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For instance, once each interchange alternative has been analyzed, a central database of performance measures can be accessed at any time to produce comparison reports, thereby simplifying the selection process. REFERENCES Highway Capacity Manual." Special Report 209, Third Edition, Transportation Research Board, Washington, D.C.
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