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OCR for page 333
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-!
OCR for page 334
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
OCR for page 335
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
OCR for page 336
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
OCR for page 337
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)
_'
_'
OCR for page 338
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
OCR for page 339
~ ~ 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
OCR for page 340
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
OCR for page 341
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:S£reen:
~ ~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
OCR for page 342
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
OCR for page 343
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!
OCR for page 344
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 ~::'
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P~K-~? ~'I' .
P~9P2.-~7 ~
I- 4 ~:
P^-~7 4~
,.S.~?fi~ . .
~.~J,~..~'
........ . .... .... ..
- .
OCR for page 345
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
OCR for page 346
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
OCR for page 347
:.~. ~ 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
OCR for page 348
- ~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
......... ~
. . ~ ~
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Figure F-13. Enlarged picture of a diamond interchange with f nal lane analysis.
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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.
.
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OCR for page 350
Representative terms from entire chapter:
existing software
