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APPENDIX F DEVELOPMENT OF INTERCHANGE ANALYSIS SOFTWARE F.1 INTRODUCTION There are various operational software, such as PASSER I] - Ill, HCS, and TRANSYT-7F, which cart analyze the performance of different interchanges. Although each software is capable at evaluating the performance ofparticularinterchanges,none are well adapted to making a comparison among interchange alternatives because input must be re-generated for each interchange being evaluated. This appendix describes the proposed development of a prototype interchange analysis software, called INTERCHANGE, which can evaluate the operational performance of various two- leve! 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. The main benefit of INTERCHANGE is that it only requires traffic input for one interchange configuration and it automatically converts and adapts that input to all other interchanges selected by the user. This feature facilitates the process of comparing different interchange types and allows comparisons of output to be easily made as well. The following sections describe the structure of the proposed software and its potential capabilities. Also discussed is the program's current status of development end future work plans. Finally, an example problem is given to show the practical uses of INTERCHANGE and benefits to the interchange selection process. F.2 PROCEDURAL DESIGN As discussedpreviously in section 3.3.4, two optimal procedural designs of the program were proposed and are shown in Figure F-2. One proposed procedure involves using INTERCHANGE as an input and conversion software to be used in conjunction with existing software. The other procedural design creates a standalone program capable of analyzing all operational aspects of the various interchanges being compared. The left side of the diagram depicts the software design option which uses existing software to perform the analysis. As a first step, the input for one interchange form is entered which includes the honing movement volumes for one interchange form, the geometric and signalization conditions, the type of analysis requested, and the interchange types to analyze. Once these data are entered the program performs a conversion analysis which uses a database conversion aigori~m discussed later. The proposed enhancements to INTERCHANGE would produce data unique to that interchange such as honing movement volumes and required geometry for each alternative form. This converted data would then be automatically input into existing software, such as HCS, PASSER-~l, and TRANSYT-7F, for an operational analysis of each interchange being considered. F-!

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1 . INPUT MODULE 1 / / Geometric conditions Traffic conditions Signalization conditions 2. VOLUME ADJUSTMENT MODULE Peak Hour Factor Establish lane groups Assign volumes to lane groups I (INTERCHANGE Model) I \ 3. SATURATION FLOW RATE MODULE Ideal saturation flow rate Adjustment factors Adjusted saturation flows 4. 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. LEVEL OF SERVICE MODULE Compute lane group delays Aggregate delays Compute link travel speeds Determine levels of service Figure F-~. Recommended interchange operational analysis procedure Aid. F-2

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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. F-3

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The output from these existing software would then be viewed through INTERCHANGE to create a common output screen for ease of viewing and analyzing the performance measures. A common database of output values could be stored within INTERCHANGE to facilitate the comparisons. As a last step, the output could be used to revise the initial design assumptions to further optimize the initial design. As a standalone program, the proposed software would perform the same input and conversion analysis; however, the analysis would be performed within the program itself. 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. The output could then be tailored to produce useful results for different users. ~ ~ e ~ ~ ~ ~ F.3 TURNING MOVEMENT VOLUME CONVERSION Whether performing an operationalanalysisofintersectionsor interchanges, one ofthe first steps is inputting Ming movement volumes into the existing operational software. To efficiently analyze and compare the capacity and perfo~ance of venous proposed interchange alte~nativesw~ an existing interchange or intersection, a methodology needed to be developed for converting volumes from He existing condition to the proposed alternatives. Current practice involves converting the volumes manually and inputting them into operationalprograms, such as PASSER-IT, HCS, and TRANSYT-7F. No software exists which specifically converts volumes among the various interchange types. Figure F-] will be used to illustrate the methodology for converting the turning movement volumes. After the existing traffic conditions have been entered in the input module, part of the volume adjustment module can be used to convert these traffic or turning movement volumes to other interchange forms for further capacity and measures of Derformance comcansons. Other inDut , . , ,, r - - - - ~ ~ - ~- , , ~ . . . . .. .. . . . .. . . . data such as geometries and slgnallzatlon can be converted as well, however, mrmng movement volumes will be used for this example. To convert the volumes, the software utilizes a database conversion algorithm that only requires the user to enter the turning volumes for one interchange form. This initial form can be either an existing at-grade intersection which may be upgraded to an interchange or an existing interchange which needs modifications to cone with growing traffic congestion. ~in, In the next step, the converted turning movement volumes can then be input into various operational software packages such as PASSER Il. HCS, and TRANSYT-7F or analyzed using a standalone program. The advantage to the latter option is the ease of use to the user and efficiency of operation. A single software package would also have He capability of creating a feedback loop to re-adjust certain parameters and re-run the analysis. Future versions of INTERCHANGE can have the capability of performing either option. F-4

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A flow diagram of the database conversion architecture is shown in Figure F-3. As shown in the diagram, the core turning movement volumes are the central database of the program. 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. Any charges made to the inputs are immediately converted to the core database arid ready to be converted to the over interchange types as they are selected by the user. (P 4 B B) Pi BAN ~P4AB~ iN T E R) a\ .~ P4AA~c 1 Core \. :SPDF~ \< ; \ Volumes / \ ~J (P2 BA) _' (P 2 A B) _' - Figrure F-3. Database architecture of INTERCHANGE software. F-5 diamond) _' _'

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F.4 CURRENT STATUS OF DEVELOPMENT The prototype for INTERCHANGE has been developed to convert turning movement volumes among 10 different interchange types including an at-grade intersection: namely, the diamond, single-point diamond, parclo 2-quad and 4-quad configurations. The conversion database architecture described earlier was used to perform the conversions. Input screens similar to Figure F-5 were developed using the Visual Basic programming language which is adapted for use with a Window's environment. Particular attention was paid to developing a graphical user interface Cat would be understandable end easy to use. Two different input screens were developed as described in the following section to adapt to different user needs. . In addition to the turning movement conversion, the program has also been developed to provide a simple lane analysis for demonstration purposes. Based on the turning movement volumes, the program calculates the required number of lanes for each approach movement by using specific guidelines from Chapter 9, Appendix ~ of the ~ 994 Highway Capacity Manual (HCM). For instance, an exclusive left-lane is provided when left-turn volumes exceed ~ 00 vph and a double left- lane is provided for left-turn volumes above 300 vph. The user is allowed to interact with the analysis by entering in existing lane configurations and by overriding certain lane analysis calculations. This feature provides the user with a certain amount of control over the analytic procedure as well as flexibility in the use of the program. The program structure was creased to allow further enhancementsto be made to the program. New modules or additional items can be easily added in He fixture. 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. Finally, the level of service module can be coded to display the performance measures and provide a means of displaying the interchange comparisons. F.5 EXAMPLE PROBLEM An example of the program is shown in the following graphics which show the conversion ofturning movement volumes between an existing at-grade intersection end two proposed alternative designs: namely, a partial cloverleaf 2-quad AA, and a diamond configuration. At the end of this section, an example of the lane analysis procedure is shown. interfacing capabilities, a hypothetical at-grade intersection with fixture turning movement volumes was created and is shown in Figure F-4. The norm and south through movements have very high volumes of ~ ~ 00 vph and ~ 300 vph, respectively. Delays of 288 and 258 sec/veh, respectively,were output by PASSER IT arid are shown in Table Fit. Removing He through movements would improve the delay and level ot service considerably. therefore, a grade-separated interchange is envisioned to eliminate the heavy through movements. Due to hypothetical ROW, safety, and cost constraints, it was presumed that He two most favorable alternatives are the partial cloverIeaf2-quad AA and the conventional diamond configurations. ~ _ To demonstrate He program's ,. . . .. . ~ . .. ~ F-6

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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. F-7 00 400 \ ~ am\ <13 210 - - it= A\ - \ - ' 210 1 300 300

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A step-by-step coding of the hypothetical example into INTERCHANGE will now be described. To begin, the user starts the program with the opening screen, shown in Figure F-5, entitled "Input Screen's as most of the data are input here. 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. Clicking on the 'burning movement volumes" column causes a small fonn to open, as shown in Figure F-6, which is used for entering turning movement volumes. As the values are entered, He directional arrows, which correspond to that movement, enlarge In the small picture ofthe interchange. This indication eliminates any confi~sionas to which movement is being coded. In addition, directions to the user are continuously being provided at each step Trough a small screen in He upper right-harld corner. Table F-~. Performance of At-Grade Intersection with Future Turning Movement Volumes Using PASSER I! PerfonnarlcePhase Movement Desi~ation(Nema) (2) MeasuresNote: Movement 6 & 2 correspond to N-S movements. 1 5 1 6 ~ 2 3 4 7 8 Volumes1 210 1 1600 110 1600 210 300 90 500 V/C ratio0.58 1.33 0.31 1.3 0.45 0.5 0.22 0.78 _ ~ _~ _ ~ _ Delay (sec/veh)13.8 288.3 1 1.2 258.5 14 22.8 13 28.8 _ ~ _~ _ ~ _ Level of Service B F B F B C B C Volumes * 210 500 1 10 300 210 300 90 500 V/C-RATIO * 0.51 0.88 0.19 0.53 0.45 0.5 0.22 0.78 DELAY (SECS/VEH)* 12 32.5 7.6 16.6 14 22.8 13 28.8 LEVEE OF B D B B B C B C SERVICE* Note: * indicates values without N-S Trough movements. F-8

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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 .. .... . . ~ . . . . ..... ... . ~ ~: ~. ~i. ~ ~. . ..... ~ . . . ... : . .. . . . .. ::., ::.:i.....,;..:...,..,.~,;..: ......:......~......:...:.~.............:...:. ::..:.......:.:.:: :..:....:....:..::..:.:...: :.~...:.-..:. ::.:.:.;..:.:..:..:.:. :....:~..:....~....;.. ....:...:.~.:..:....:..:..... Figure F-5. Input screen with small picture of an at-grade intersection. . . . . . .... .. . . ~...... . . . . . . .. . ... . . . . . . . . . .. . . . . . . . . . . . . . . . . . . .. . .. . . . . . . . . .. . . . ... ... .. . . .. . . . . . .. . . . . . .. . . . . . . .. : : ::; : ~ nput:S=een: : :~ . . . . . .. . . . . . . . . . . . . . . . . . . . .. . . . . . .. . . .. . .. . . . . . . . . . . . . : ~ : ~ Twning Humble: SaL Iircen Red ~ : : : : t~low'nutt of Flow :-l:^u~:: : T:~ ~ ~ ~ ~ BY: Low :: ::~: :: ......... . .............. ................. .. . ... : ,: -:. :' :.::: :.VP ~ :. .: .... - ~ , ~-. sat, ... . . , .... ..... . . :::: lrectlans ~ ::: :: :: ::: 11~ ~r 1 ... ... . .. .. . . ........ ... . - . ~ i. - ~ . ~ . ~ - . :,:, . ,. - ... ,, ., , ,., ~^ ~: :.:.: ~:~.: : ; ,. ;: ~ . : : ~ ~ : :~ : ~ : ~ ~ : :-::::~:: ~: ~ ~ Input:Sreen: ~ ~T~um~ng :~-HuiDb - ~:S^~: ~Gr~n :: : ;~ Mov' - * of Flo. :Ti - o ::: ,'~--:.Pl)~,~ '~ :~ '~ '~ ~#C:: - , : . . .... .. -~:hoose One : ~ ~'amond ~ ntetchar~e O Parciv 2-Ou23s' Ah O P~ft lO 2_~6 ^s O P~:~o 2-~ard SA O Patolo ;2 auad BS ~ P.31C,\43 4-~& ~ ~fOlO 4-Ouad AB PatcIo 4-~d BA O Parcto 4-~ad BS O S'ngIo-P<3'nt ~.~. 6) Core Inter#ction . . . : :-: ~ . .. ~ ~: ~:~6d " ~ . _ . ::' ~ : : ~: #c: IJ1 l~l +~. h~ _ lln~t~r : :~ ;: ~:'' Figure F-6. Small picture of at-grad~e intersection with input form. F-9

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The proposed freeway will run north-south and eliminate the heavy north-south Trough turning movements volumes: namely, the 1100 vph south and 1300 vph north volumes. When coding the future at-grade intersectionturning movement volumes into INTERCHANGE,the north- south through movement volumes are entered in normally as is shown in Figure F-6. An enlarged picture of the intersection can be viewed by clicking the "Max" button. Figure F-7 shows the screen ofthe enlarged at-grade intersection. 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. ~ ~ 4 ~ 500 BERM 1 ~ 1 ~ . B_ ~ 180 . . b 1~ ~.............. : __ ~ 200 >~ +~ it.; ,..i~~ ~^ N i: .... _ ...... I ; ..... t}~7~: aft ~ ..... - -: : ,, . ,. . T ... ~,Jr3~ :2' ,:', ', ,, . :::::::::: :::-::::: :::::::::: ::.. ~:, P~5,`2.- ~:. /~=,,'~7 ~:.~ Pi', 2~:~ p - ,'~7 p~'~7 ~I: ~?,'~7 ~: . . ~^'~7 4 P^'~7 4 ~Foi)tDh Kern ._. ~ . ............. . . Am_ . . .. . . . I . .. .. .. .... . ... .... .. . ..... ... ..... . ... . . . .. .. L ~ ~ ~ ~ _ Figure F-7. EnIargedpicture of at-grade intersection. To compare the existing at-grade intersection with the partial cloverleaf 2-quad AA Loran, the user can either return to the original screen with the smaller pictures or choose an enlarged picture ofthe 2-quad AA form from the drop down menu box at the top right of the screen. Figure F-8 shows the results of choosing the latter. The enlarged partial cloverleaf 2-quad AA picture has F-10

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the conversed turning volumes already automatically provided on the interchange approaches. The norm and south through and U-turn movements have been eliminated since it was assumed that these movements are not served properly by this interchange form and therefore their use is discouraged. The user can readily compare another interchange form to the original intersection or minimize the enlarged interchange drawing by clicking on the "Min" button at the lower nght. Figure F-9 demonstrates the results of choosing to compare the existing at-grade intersection and partial cloverleaf2-quad AA alternative with a second interchange alternative, in this case a diamond interchange. As with the cloverleaf, all the movements are automatically provided on the diamond interchange approaches. Note how the east and west right and left Wing movements have exchanged volumes during the conversion between the two interchange configurations. The north- south through movements present in the at-grade intersection, namely 1300 and ~ 100 vph, have been replaced by default frontage road through volumes (0 vph in this case) in the diamond interchange configuration. The through movements for both of these forms we remain mutually exclusive thoughout the program. The results of a compar~sonofmeasures of performances generated by PASSERI] are shown in Tables F-2 through F-4. Table F-2 shows a compar~sonof system delay and average intersection delay. The diamond interchange performed slightly better than the parclo 2-quad AA with system delays of ~ 5.65 sec/veh as opposed to ~ 8.9, respectively. Delays associated wad both the left and right side intersection of each interchange are shown in Table F-3. On average, the left-side intersection of both interchanges provided better performance for the future mining volumes than the right-side. This can be attributed to the higher turning movement volumes that used the left side; namely, the high west-bound left turning volumes, 200 vph, and the high southbound right movements, 500 vph. Significant fluctuations in performance measures were seen in the parclo 2- quad 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. The parclo 2-quad AA also experienced similar Fluctuations in volume-to-capacityratios for each turning movement as shown in Table F-4. Fat!

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1~ d~ Gl;~ __ 10 ... ~ ......... ..... 180 . . . it. ~ .. ..... . ~ Cal : . _, ................. : (~ .. .. ...... . . ~ CZAR', .: I: :~ : : OSWALD : ~ . . . . : :~ .. , , ., , ... . .. = P~2-~, ~,.,~. P~-~7 ~. . p,m'~7 ~ ' P~-~ ~'-. ^~'~7 ~' . P.s,2.-~7 4 ~: .,S~?fi~fO~ ~.~f~.-~ : Figure F-8. Enlargedpicture of a partial cloverleaf 2-quad AA. JlU ~ 50~ ......... ~i '' _, ~ 210: ~. . . 1~1~1~1~ ~. ~.... . . . .. . 1Pi~ 1 .......... Figure F-9. Enlargedpicture of a diamond interchange. F-12 . w ..... .. ........ ~:w~.7,c~.~7a - : . .: . . ... ~ . ~ . . .......... DAM; - :.: I:: I: : : 1 ., ..,, ....,. _ ... . ............ _ _,'2 . P.5K- ~. :. PI.5K-~7 ~::' P..jK-~ P.ib~2,-~,7~ ;? : P~K-~? ~'I' . P~9P2.-~7 ~ I- 4 ~: P^-~7 4~ ,.S.~?fi~ . . ~.~J,~..~' ........ . .... .... .. - .

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Table F-2. Comparison of System Delay and Average Intersection Delay . _ _ _ r Interchange System Delay Type (sec/veh) Diamond 15.65 Parclo 2 AA 18.9 Avg. Intersection Delay(sec/veh) 16.7 20.7 Table F-3. Delay Analysis for Left and Right-Side Intersections Using PASSER I] .. Interchange Type I PASSER IT Movement Designation ~1 5 1 6 1 1 1 2 1 3 1 4 1 7 1 8~ 1 l 1 1 1 1 1 1 ~ *25.1 11.5 24.2 23.3 0 20.2 11.3 0 36.3 30.3 0 7.9 0 27.3 : 7.6 14.2 *24.8 13.3 16.5 0 - 0 8.1 20.8 16.2 14.8 0 Left-Side Diamond Parclo 2 AA Right-Side Diamond Parclo 2 AA Note: ~ indicates u-turn traffic with no-bay 12.8 0 = o lo 19.6 17.2 Table F-4. V/C Analysis for Left and Right-Side Intersections Using PASSER I! ||Interchange type | Is Left-Side Diamond *0.06 PASSER Il Movement Designation l 6 0.56 0.59 2 1 3 I 0.59 1 0 - 0.76 1 I I I ~I l 1 1 1 1 1 P~c102AA Right-Side Diamond 0.78 0.31 0.81 0.51 o *0.06 0.1 0.14 0.31 1 0.31 o 0.38 0.84 o 7 1 8 1 0.15 0.15 1 to 1 0 1 0.6 l l 1 1 1 1 Parclo 2 AA o 0.31 0.33 o lo 0.55 Note: ~ indicates u-turn traffic with no-bay F-13

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The previous analysis assumed that the lane configuration was the same as that shown in Figure F-4. To evaluate various lane configurations,the user can employ the lane analysis features of INTERCHANGE which was designed to allow the user a certain amount of interaction in the analysis process. 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. This latter choice allows the existing condition to be compared with the optimal lane configuration provided by INTERCHANGE. Figure F-l ~ shows the results of the program's lane analysis, whereby the lane analysis results are shown in their respective boxes. [ - e Analysis Screen 44W ~ ~ ~ Berm D in ~ it: ... . . . ~ Hi=. 1. _ - - 1 1 1 ~ D nob ~ rip .... .. ~ . ~ .. . .--. . .~. ............ .. ... . .. . _. Pa- ,~':'. P=-~7 ~:. . It'd? ~ pi, 3,'? ~. Pa Pow, 4 P=~74 . '? .. ............ .... ................................. , ,,, . . .. , , , , , , , . ~, , ~ Figure F-l O. Eniargecipicture of diamond interchange with lane analysis screen. F-14

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:.~. ~ 1 ~ Lane Analysis Screen it| L~neAn.~ysis | ~r 14 ~ 1 1 ... . . ............................................................. nor 4~ rip try 1 1~ ins ~ I_ ,: ~ , ,:, :, :,,:,,, :::: :;: ': :'^,,~ .''.:.: :'. 'a . . ~.rz?;~.A~r.... . ........................ .... .. . , ... ...... ... . . .: ~?~;~ :~: ::' :':. it' P^'~7~ Pmd7~ Ilk' ^ Plink? P=' PI' P='~ 4 Pent 4 .~0Pr Figure Few. Enlarged picture of a diamond interchange with lane analysis results. The user still has the option of re-entering a desired lane configuration after the lane analysis results have been shown and running the analysis one more time. If the user changes certain minimum requirements, for instance, removing a led turn bay, the program wall then prompt the user, as shown in Figure F-12, Mat certain minimum requirements, such as minimum number of exclusive left-lanes, has been violated and whether to continue to override the minimum values. Dependent on the response of the user, the program w~11 either keep the minimum number of lanes or use the user inputted value. Any additional lanes required are added to the through lanes as shown in the final lane analysis results in Figure F- ~ 3. For instance, an additional lane has been added to Westbound through movement at the left-side intersection as a result of the user choosing the "no lane" option as demonstrated in Figure F-12. F-IS

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- ~J : coxed ~ : . ~ :: : If: . :~ - P.;K'~7 ~: P^-~7 P=-~7.= P^-~7. P.;8Q'~7 ~"1"} P~'~7 P='~7 4 ~: P,3JI-'~7 4 ~: ,S~ - fewer ~.~ I-., Figure F-12. Enlargedpicture of a diamond interchange with lane analysis user prompt. Lane Analysis Screen | ~ ~ ~ ]~ R~ucs~ec ~N lilt . __ O ~2 ......... ~ . . ~ ~ ~. ~ ~ I~I:FI: n ~ ~ re .. _, ........... A . ' ~C7t,~i ,~, .-A: ' ' ,,,, , . .-:.` '. '.'' :' ' ' ''' ' ' ' ''2~'' ~2.'~'. ,', ,' '. . ,: P=-~ PI P='~7 P=-~7 P~-~7 P~K'~7 P^~7 4 P~2~7 4 ~ "So - If '~'2 If-. i, ... . ................... .. . .. ... . . : - . . .. :4> . ' ~ . ' . 2. - t : :.:::: :: ::: : ::::::::: :.:: :: ... . . ~ ::: :-:::::::: : .:: .: .:: ~ .. .. .. .. : . ., . . ., : . 4 ......... . - : ...... , ' -, '': ' . . . .. . - . . ... .. . . . . .. . .'~ : g 'g. . :R : g . g . ',: ,4 :: :; ~.4 ., ~.i .. 4 Figure F-13. Enlarged picture of a diamond interchange with f nal lane analysis. F-16

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. As demonstrated in this hypothetical example, INTERCHANGE can be a very useful too} for interchange analysis and comparison. Having a standalone program, as suggested in Figure F-2, can greatly improve the efficiency of the analysis as shown by using PASSER II results. Perfonnance measures can be calculated within the program and be output for individual interchange analysis or for comparison purposes. 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. (1994~. Messer, C.~., and C.P. Chang. "Arsenal Signal Timing Optimization Using PASSER Il-90." Report 467-2F. Texas Transportation Institute, College Station, TX. (1991~. Van Arendonk, I. "Development of en Interchange Analysis Software."M.S. Thesis. Texas A&M University, in press, College Station, May 1 997. . F-17

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