Citation
Accident and capacity comparisons of leading and lagging left-turn signal phasings

Material Information

Title:
Accident and capacity comparisons of leading and lagging left-turn signal phasings
Creator:
Sheffer, Christopher R
Place of Publication:
Denver, Colo.
Publisher:
University of Colorado Denver
Publication Date:
Language:
English
Physical Description:
ix, 73 leaves : illustrations ; 28 cm

Thesis/Dissertation Information

Degree:
Master's ( Master of Science)
Degree Grantor:
University of Colorado Denver
Degree Divisions:
Department of Civil Engineering, CU Denver
Degree Disciplines:
Civil Engineering
Committee Chair:
Janson, Bruce N.
Committee Members:
Kahn, Sarosh I.
Hughes, William C.

Subjects

Subjects / Keywords:
Electronic traffic controls ( lcsh )
Traffic engineering -- Colorado -- Arvada ( lcsh )
Left-turn lanes ( lcsh )
Traffic flow ( lcsh )
Electronic traffic controls ( fast )
Left-turn lanes ( fast )
Traffic engineering ( fast )
Traffic flow ( fast )
Colorado -- Arvada ( fast )
Genre:
bibliography ( marcgt )
theses ( marcgt )
non-fiction ( marcgt )

Notes

Bibliography:
Includes bibliographical references (leaf 73).
General Note:
Department of Civil Engineering
Statement of Responsibility:
by Christopher R. Sheffer.

Record Information

Source Institution:
|University of Colorado Denver
Holding Location:
|Auraria Library
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
41470992 ( OCLC )
ocm41470992
Classification:
LD1190.E53 1998m .S44 ( lcc )

Full Text
ACCIDENT AND CAPACITY COMPARISONS OF LEADING AND LAGGING
LEFT-TURN SIGNAL PHASINGS
Christopher R. Sheffer
B.S., Michigan State University, 1982
A thesis submitted to the
University of Colorado at Denver
in partial fulfillment
of the requirements for the degree of
Master of Science
Civil Engineering
1998
by


This thesis for the Master of Science
degree by
Christopher R. Sheffer
has been approved
by
Bruce N. Janson
/z//o/?e


Sheffer, Christopher R. (M.S., Civil Engineering)
Accident and Capacity Comparisons of Leading and Lagging Left-Turn
Signal Phasings
Thesis directed by Associate Professor Bruce N. Janson.
ABSTRACT
Many traffic engineers nationwide are reluctant to implement lagging left-turn
phasing plans along arterial streets, even though signal progression can
sometimes be significantly improved. A popular opinion among many
agency engineers is that lagging left turns are contrary to driver expectancy
and cause an increase in start-up lost time. To prevent the left-turn trap
where opposing left-turn vehicles may be caught unaware of the extended
lag phasing they are facing, many engineers will not allow permitted left turns
at these intersections. This paper compares saturation flow rates, start-up
lost times, fourth vehicle crossing times, and accident rates between
protected-only lead and lag left-turn phasings in the Arvada, Colorado area.
All four measures were found to be better for locations with lag phasing than
with lead phasing, although both saturation flow rates and accident rates
were not statistically different. While further studies are needed, these
findings suggest that a mix of lead and lag protected-only phasing for left-
iii


turn vehicles may be used to improve signal progression without
compromising safety or capacity.
This abstract accurately represents the content of the candidates thesis. I
recommend its publication.
Sign
IV


ACKNOWLEDGMENTS
Acknowledgment is gratefully given to Dr. Bruce Janson of the University of
Colorado at Denver for providing the insight, direction and input for this
paper. Acknowledgment is also extended to Joe Resseguie, Traffic
Operations Engineer for the City of Arvada, for his information and insight of
the study area.
v


CONTENTS
CHAPTER
1. Introduction........................................................1
1.1 Purpose of Study ..................................................1
1.2 Background ........................................................2
1.3 Benefits of Lead/Lag Left-Turn Phasing.............................5
1.4 Previous Studies..................................................10
2. Data Collection ...................................................13
2.1 Study area .......................................................13
2.2 Data Collection Procedure........................................19
3.0 Data Analysis....................................................22
3.1 Traffic Flow Measure Calculations................................22
3.2 Statistical Results of Traffic Flow Measures.....................25
4.0 Accident Analysis................................................28
5.0 Conclusions .....................................................39
APPENDIX..............................................................41
A. Accident Data.....................................................42
B. Signal Timing.....................................................55
C. Saturation Flow Data..............................................69
vi


REFERENCES.
73
vii


FIGURES
Figure
1. Lead/Lag, Lead/Lead, and Lag/Lag Phasing............................1
2. Lead/Lag Signal Progression along Wadsworth Blvd....................6
3. Lead/Lead Signal Progression along Wadsworth Blvd...................7
4. Laneage Configuration for Wadsworth Blvd............................17
5. Laneage Configuration for Aurora Intersections......................18
viii


TABLES
Table
1. Traffic Signal Timing................................................21
2. Comparison of Traffic Flow Measures for Lead Versus Lag Left-Turns. 27
3. Left-Turn Accident Rates Along Wadsworth Blvd........................33
4. Left-Turn Accident Types Along Wadsworth Blvd........................35
5. Left-Turn Accident Causes along Wadsworth Blvd ......................36
ix


1. Introduction
1.1 Purpose of Study
Alternative left-turn phasing has been instrumental in improving traffic signal
progression along many major arterials and highways. Different left-turn
phasings have been looked at in the attempt to improve signal progression,
and ultimately traffic flow and air quality. With the passing of ISTEA, the
objective of improving air quality has been the focus of many traffic operation
improvements. Many City, County and State agencies have developed
policies regarding the use of less common signal phasings such as lag left-
turn and lead/lag left-turn phasings. Many agencies have a preference for
using lead left-turn phasing at intersections were protected-only left-turn
phases are needed. Although the use of lead/lag phasing can greatly
improve signal progression, a popular opinion is that capacity and safety are
affected when driver expectancy is violated with these alternative phasings.
The focus of this paper is to compare accident rates, saturation flow rates,
start-up lost time, and fourth vehicle crossing times, with protected-only lead
and lag phasings. It is anticipated that driver expectancy differences will be
seen through differences in these four measures.
1


1.2 Background
Lead/lag left turn phasing at a 4 legged intersection is accomplished in three
phases. One direction of through-plus-left-turn traffic proceeds first, followed
by both directions of through traffic and finally allowing the opposite through-
Figure 1 Lead / Lag, Lead / Lead, and Lag / Lag phasing
Phase 1 lw * It
Phase 2 It It *
Phase 3 Lead/Lag
Lead/Lead Lag /
Lag
plus-left- turn traffic to proceed through the intersection. The lead left-turn
phase occurs during the first phase and the lag left-turn phase follows or
lags after the second through movement phase. Lag/lag left-turn phasing
follows a similar sequence as lead/lead left-turn phasing. Both of the left-
turn phases simply lag behind the through green phase.
This flexibility in left-turn phase order allows more opportunities for better
signal progression and wider bandwidth. In addition, system delay can be
minimized by accommodating different platoons of traffic. The optimization
2


of signal progression can effectively be done by using combinations of lead/
lead, lag/lag and lead/lag left-turn phasing. Computer programs such as
Passer II utilize this technique to optimize bandwidth.(1) Several cities in
states such as Arizona and Texas commonly use these phasings to
accomplish better operations.
One important safey issue arrises when lead/lag left-turn phasing is
implemented along with protected/permitted left-turn phasing. This issue is
commonly referred to as the left-turn trap. In many states such as
Colorado, it is legal to enter the intersection on a yellow indication and the
driver can clear the intersection during the all-red phase when opposing
traffic has come to a stop. Typically the lead left-turn driver will expect to be
able to complete a permitted left-turn during the yellow or all red phase if
necessary. With lead/lag left-turn phasing, the lead left-turn drivers opposing
traffic, traffic in the direction of the lag phase, will not stop at the end of the
lead side through phase. The lag side through movement continues to be
green into the lag left-turn phase. The lead left-turn driver is thus tricked into
thinking opposing traffic will stop at the end of the permitted phase. It is
because of this that the most common practice is to use protected-only
lead/lag left-turn phasing. One exception to this is the so called Dallas
3


phasing in which the left-turn traffic never sees the yellow phase of the
through traffic and thus the driver is less likely to make the assumption that
the opposing traffic will be stopping with the through movement. The use of
programmable signal lenses can prevent a left-turn driver from seeing the
adjacent through movement signal indication.
Note that the left-turn trap can only occur when permitted left-turns are
allowed with the opposing through movement phases ending at different
times. If lag/lag or lead/lead phasings are used at pre-timed signals, the
permitted left-turn movement will not experience the trap because both
through movement phases will end at the same time.
In the case of an actuated signal, where a left turn phase may be skipped
due to non-actuation, the controller will release the opposing traffic early.
The additional time for the non-actuated left turn is added to the opposing
through movement. This is not a problem under lead/lead phasing because
both through movement phases will terminate at the same time. In the case
of lag/lag protected/permitted phasing, the trap can exist if one of the left-
turn phases is not actuated.
4


1.3 Benefits of Lead/Lag left-turn phasing
The technique of using different left-turn phasing to optimize arterial signal
progression allows more flexibility in finding optimal bandwidth and delay
solutions. By mixing the use of lead/lead, lag/lag, and lead/lag phasings,
many more possibilities for better solutions exist. Although the ability to use
all three phasings is optimal, the focus of the analysis will be on lead/lag
phasing since it allows the analysis and comparison of both lead and lag
phases at the same intersection. It is also the most complicated of the three
phase orders and has the most operational and safety issues associated
with it.
Figures 2 and 3 are Time/Space diagrams along a segment in Arvada,
Colorado of State Highway 121, also known as Wadsworth Boulevard. For
demonstration purposes, an approximate signal timing along a portion of
Wadsworth Blvd during a PM peak was used. The bandwidth is optimized to
favor the predominate flow of traffic along this portion of Wadsworth Blvd.
The posted speed limit of 45 mph is the assumed progression speed
between
5


Wadsworth Dlvd
45.0 ripli.
o\

ifi*****
A**'

i\cfcfc
^seo'

45.0 mph
SWhb,
Und bg,
naWdth
28
Seco,
nofs
45:0 mph...
GSlh
Figure 2
Lead / Lag Signal Progression along Wadsworth Blvd
Thu. 6/25/90 21:44
"'45.Q mph .tv
"45.Q mph.?.->
76th Ave'
i~"
77th Ave
45.Q mph.
80th Ave


Wads worth Dlvd
45.0 mph. ...


,6^

^ 60
\\o'
45.0 m ph ::: U^^0Uri(j /
UW,ath1?0 ...
........ SeCo/i-i t T.tja -
^nas
45.0 mph -
Thu. 6/25/98 21:46
45!0 mph
45:0 mph
45:0 mph
68ih
7 6 tin Ave f
Figure 3 77th Ave
Lead / Lead Signal Progression along Wadsworth Blvd.
80lh Ave


the selected intersections. For the purposes of this example, side street
phase splits were assumed for 77th Ave and 76th Ave. The comparison of
the following two conditions help to illustrate the benefits of lead/lag phasing.
1. Lead/lead left-turn phasings at 68th Ave and 80th Ave.
2. Lead/lag left-turn phasings at 68th Ave and 80th Ave.
It can be seen that with the lead/lead phasing, the northbound direction can
only experience a bandwidth of 33 seconds at 45 mph and only 17 seconds
in the southbound direction at 45 mph. The lead/lag phasing allows for
bandwidths of 37 seconds in the northbound direction and 28 seconds in the
southbound direction at 45 mph. The ability to shift the beginning of the
through movement green time in one direction, with lead/lag phasing, allows
more flexibility in optimizing the bandwidth for both directions. This technique
is powerful in optimizing bandwidth to meet the speed and intersection
spacing constraints of the particular arterial. It is interesting to note that the
lead/lag condition allows for more cross street green time at 77th Ave.
This is one example of the benefits that the flexibility of different left-turn
8


phasings can create. It is interesting to note that using a different
progression speed could result in greater bandwidth in the southbound
direction with the lead/lead condition however, a higher progression speed
would encourage drivers to exceed the speed limit.
9


1.4 Previous Studies
While much research has been done on left turn phasing, little research has
compared traffic flow and safety measures in cases with protected-only lead
and lag left-turns. Some studies have shown that higher accident rates are
associated with permitted left-turn phasings than with protected-only
phasing.(2) The trade off is a loss in capacity due to the inability to allow
permitted left-turns. With the use of lead/lag left-turn phasing, a substantial
benefit in arterial signal progression and system delay must be realized to
overcome this loss in capacity. This is true if the left-turn trap is to be
avoided by not allowing permitted left turns.
One study, sponsored by the Arizona Department of Transportation,
compared accident rates for five combinations of lead and lag left-turn
phasings including protected-only lead and lag phasings.(3) While the
protected-only lag phasing had a very small sample size, this study found
that protected-only lead phasing had the lowest left-turn accident rates. It
was interesting to note that in this study, the protected-only lag phasing had
less than half the accident rate that the protected-only lead phasing did for
intersections with 3 opposing through lanes. The opposite was true for
10


intersections with 2 opposing through lanes. In the same study, conversions
from protected-only lead to protected-only lag phasings showed an increase
in accident rates at intersections with 2 opposing through lanes, and no
increase with the same conversion at intersections with 3 opposing through
lanes.
Another study evaluated delay for three different leading and lagging left-turn
phasings at one intersection.(4) Left turn delay for leading protected
/permitted was lower than for lagging protected / permitted phasing. The
study did not however, consider signal progression or the adjustment in
offset phasing conditions that may effect upstream traffic and the platooning
of traffic.
In discussions with various agencies, the stated reasons for not using lag
left- turn phases varied. The violation of driver expectancy was listed as one
reason. Some agency engineers felt that the surprise of having a different
order of phasing increased the amount of start-up lost time for the left-turn
traffic. Some cities observed increased queue lengths spilling back into the
through lanes at approaches with lag left-turn phases. The reluctance to give
up capacity by eliminating the permitted phase was yet another reason given
11


for not considering lag left turns.


2. Data Collection
2.1 Study area
This paper examines signalized intersections with lead/lag phasing along a
major arterial in the Arvada, Colorado area. Wadsworth Blvd. or S.H. 121
extends north and south through several cities including Arvada. The original
lead/lag signal timing was implemented by the City of Arvada after the City
eliminated the permitted left-turn movements at many of the intersections
along Wadsworth Boulevard. Due to safety reasons left-turn arrows were
installed because of the difficulty of traversing 3 or more lanes of traffic while
making a permitted left-turn. With protected-only left-turn phasing in place at
these locations along Wadsworth Boulevard, the left turn trap could be
avoided and the option of lead/lag phasing was now feasible. The City of
Arvada then re-timed various traffic signals with lead/lag phasing to increase
signal progression bandwidth along its stretch of Wadsworth Boulevard. In
1991 the Colorado Department of Transportation (CDOT) assumed the
maintenance and timing of Wadsworth Boulevard, and chose to continue the
use of lead/lag signal phasings along Wadsworth Boulevard.
The following six Arvada intersections with protected-only lead/lag phasing
13


were selected for accident comparisons:
1. Wadsorth Boulevard and 52nd Avenue
2. Wadsworth Boulevard and 53rd Avenue
3. Wadsworth Boulevard and 55th Avenue
4. Wadsworth Boulevard and 64th Avenue
5. Wadsworth Boulevard and 68th Avenue
6. Wadsworth Boulevard and 80th Avenue
Figure 4 shows the intersection laneage at each of these intersections.
In addition, saturation flow rates, start-up lost times, and fourth vehicle
crossing times were compared at the following intersections:
1. Wadsworth Boulevard and 80th Avenue
2. Wadsworth Boulevard and 88th Avenue
3. Parker Road and Quincy Avenue (Aurora)
4. Hampden Avenue and Chambers Road (Aurora)
Data was collected from the two Wadsworth intersections to represent the
lead/lag phasing data set. Traffic data was only collected in the lag phase
14


direction at the Wadsworth intersections to eliminate the possibility that
driver confusion may also affect driver behavior in the lead direction of the
intersections with lead/lag phasing. Two intersections in the Denver suburb
city of Aurora, were analyzed. These two intersections were used to collect
data from typical intersections with lead/lead left-turn signal phasings.
Figure 3 shows the intersection laneage of the Aurora intersections. These
intersections were carefully selected to maintain good consistency for
comparison purposes. Note that the data collected at all four intersections
were taken at similar approaches that included protected-only left-turn
phases and dual exclusive left-turn lanes.
The assessment of capacity (Saturation flow) and start-up lost time, per
Highway Capacity Manual (5) criteria, requires that queues of more than four
vehicles be consistently observed at the intersection. The above
intersections were also selected due to the longer queues that were
observed during the peak hours.
Another benefit to this particular study area is that both lag and lead sides of
the same intersection can be compared from a safety perspective. Accident
rates can be easily compared because each intersection has similar
15


geometry, volume and driver characteristics.
16


FIGURE 4
Laneage Configuration for
Wadsworth Blvd (S.H. 121)
* denotes intersection approaches
where saturation flows were measured
88th Ave
80th Ave
68th Ave
64th Ave
55th Ave
53rd Ave
52 nd Ave
/ay *


*
lag


lag
-r-
mtttf
lag


lag
lag
m *_ V"
-*
lag
-t- IP

17


FIGURE 5
Laneage Configuration for
Aurora Intersections
* denotes intersection approaches where saturation flows were measured
Quincy Ave
Parker Rd Barker Rd / Quincy Ave Intersection
m Hampden Ave nttti*,
Chambers Rd Chambers Rd / Hampden Ave Intersection
18


2.2 Data Collection Procedure
Saturation flow headways and start-up lost times were collected at the
sample intersections both with a stop watch as well as with a video camera.
The video was used primarily to verify information that was collected with the
stop watch. The procedures outlined in the Highway Capacity Manual (5) for
direct measurement of prevailing saturation flow rates were used.
Headways after the fourth vehicle were used to determine the Saturation
flow rate and the average headway of the first four vehicles minus four times
the saturation flow rate defines the start up lost time. This procedure
recommends that at least 15 cycle lengths be observed in order to obtain
statistically significant data. Queue lengths of 8 or more vehicles are
recommended, however, at Wadsworth Blvd and 88th Ave., additional signal
cycles were recorded to improve the statistical significance of the data. In
this case, the left-turn timing would never allow for more than six vehicles
per phase to be served.
Signal timings for each of the intersections were obtained and field verified.
In some cases, lead/lag phasing was in place only during the peak hours.
The selected intersections were chosen in part because they have lead/lag
19


phasing during the majority of the day. Table 1 shows the signal timings for
the four intersections in which saturation headways were measured. The
signal phasing and splits for Wadsworth Blvd and 80th Ave and Wadsworth
Blvd and 88th Ave. are typical of the remaining intersections studied along
Wadsworth Blvd. The original timing sheets for all the Wadsworth Blvd
intersections are included in the appendix.
Accident data was collected for the six intersections previously mentioned.
The process is described in detail in the Accident Analysis section of this
paper.
20


TABLE 1
Traffic Signal Timing
Wadsworth Blvd and 80th Ave
Phase Movements Split (Sec) Yellow (sec) All Red (sec)
1 SB+ left 13 4 2
2 SB+ NB 23 4 SB 2 SB
3 NB+ left 18 4 2
4 EB left + WB left 14 3 WB
5 EB+ left 6 3
6 EB+ WB 26 3 2
Cycle Length 100
Wadsworth Bl. and 88th Ave
Phase Movements Split (Sec) Yellow (sec) All Red (sec)
1 SB+ left 13 4 2
2 SB+ NB 35 4 SB 2 SB
3 NB+ left 13 4 2
4 EB left + WB left 15 3 EB
5 WB+ left 4 3
6 EB+ WB 20 3 2
Cycle Length 100
*Chambers and Hampden
Phase Movements Split (Sec) Yellow (sec) All Red (sec)
1 NB left +SB left 14 3 NB
2 SB+ SB left 10 4 SB left
3 NB+ SB 37 4 2
4 EB left + WB left 10 3
6 EB+ WB +per Its 29 4 2
Cycle Length 100
*Parker Rd and Quincy Rd
Phase Movements Split (Sec) Yellow (sec) All Red (sec)
1 SB+SB left+ WB right 60 3 SB left
2 SB+ NB +NB per left 35 5 2
3 EB +EB left 10 3 2
4 WB + WB left 10 3 2
Cycle Length 115
*Field measured timings (Force off)
21


3.0 Data Analysis
3.1 Traffic Flow Measure Calculations
The saturation flow rates were calculated from the measurement of
headways. The following formula was used
s= 3600/h (1)
where
s = saturation flow rate (vphgpl) (Vehicles per hour of green per lane)
h = saturation headway (sec), and
3,600 = number of seconds per hour
The Highway Capacity Manual (5) defines saturation headway as:
the constant average headway between vehicles occurring after the
Nth vehicle in the queue clears the intersection.
This is calculated after the fourth vehicles axle clears the stop line. The sum
of the first four vehicle headways is referred to as the fourth vehicle crossing
time.
The start up lost time represents the time that drivers require to react to a
phase change and accelerate and maintain saturation flow headways. This
has been defined by the Highway Capacity Manual (5) as occurring within
the first four vehicles in a queue. In other words, the first vehicle will react to
22


the phase change, and the first four vehicles will accelerate to saturation flow
headways before they cross the stop line.
The total start-up lost time is the sum of the individual headway differences
between saturation headway and headway of each of the first four vehicles.
(2)
where
Zj = total start up lost time (sec), and
f, = lost time for the /th vehicle in queue (sec)
Because the calculated lost time is dependent on the saturation flow rate,
fourth vehicle crossing times are also compared in the following analysis as
an independent traffic flow measure for lead versus lag phasing. This is
because it is possible to have a high start-up lost time that is partly due to
the high saturation flow rate.
Statistical confidence intervals were computed for the 95% level as follows:
23


X
s
s
t
g/2,n-l
~ ta/2,n-l S
, X +
fn
(3)
where:
x = the sample mean
n = the sample size
s = the sample standard deviation
t = the critical point t- distribution value for the level of
confidence a/2, and n-1 degrees of freedom.
24


3.2 Statistical Results of Traffic Flow Measures
Table 2 summarizes the statistical comparisons of these three traffic flow
measures. The sample size, mean value, standard deviation, and 95%
confidence interval about the mean is shown for each measure at each
location. Both of the lead sites and both lag sites were combined and
statistically tested using the standard two-tailed t-test of sample means(6).
The start-up lost times, and saturation flow rates generally fall within the
confidence levels that were established for a 95 percent level when
compared individually. Although the combined mean saturation flow rate is
higher for the lag left-turn phasing, there is no statistical significance.
The most noteworthy results show the combined mean start-up lost time and
combined mean fourth vehicle crossing times to be statistically lower for the
lag left-turn phasing. Also, when compared individually, each of the lag
intersections have statistically lower fourth vehicle crossing times than the
lead intersections.
The results of the analysis show conclusively that there is no greater start-up
lost time with lag left-turn phasing. In fact, there is evidence that drivers may
be more aware or anticipating the phase change with the lag left-turn phase.
25


This would imply that drivers are not surprised by the uncommon signal
phasing of a lag left-turn. Since the data was collected during the evening
peak hour, many drivers may be commuting daily through these intersections
and are familiar with these intersections.
26


TABLE 2
Comparison of Traffic Flow Measures for Lead Versus Lag Left Turns
Saturation Flow Rate tvehicles per hr.)
Location Mean Sat Flow StdDev Sat Flow No of Samples Tolerance at 95% Lower Bound Upper Bound
Parker Rd / Quincy Ave. (lead) 2106 300 30 +/-112 1994 2218
Chambers Rd / Hampden Bl. (lead) 1900 272 15 +/-150 1750 2050
Wadsworth Bl / 80th Ave (lag) 2006 321 33 +/-114 1892 2120
Wadsworth Bl / 88th Ave (lag) 2105 382 39 +/-124 1981 2229
Both Lead Sites Combined 2037 514 45 +/-154 1883 2191
Both Lag Sites Combined 2060 419 72 +/-99 1961 2159
Difference between mean sat. flow rates for the combined sites not significant at the 95% level.
Start Up Lost Time (seconds)
Location > Mean Lost time Std Dev Lost time No of Samples Tolerance at 95% Lower Bound Upper Bound
Parker Rd / Quincy Ave. (lead) 1.61 1.46 30 +/-0.54 1.07 2.15
Chambers Rd / Hampden Bl. (lead) 1.06 1.66 15 +/-0.91 0.15 1.97
Wadsworth Bl / 80th Ave Gag) 0.68 1.68 33 +/-0.60 0.08 1.28
Wadsworth Bl / 88th Ave (lag) 0.69 1.58 39 +/-0.52 0.17 1.21
Both Lead Sites Combined 1.43 1.52 45 +/-0.46 0.97 1.89
Both Lag Sites Combined 0.69 1.64 72 +/-0.39 0.30 1.08
Difference between mean start up lost time for the combined sites is significant at the 95% level.
Fourth Vehicle Crossing Time (seconds)
Location Mean time Std Dev time No of Samples Tolerance at 95% Lower Bound Upper Bound
Parker Rd / Quincy Ave. (lead) 8.59 0.87 30 +/-0.32 8.27 8.91
Chambers Rd / Hampden Bl. (lead) 8.83 0.69 15 +/-0.38 8.45 9.21
Wadsworth Bl / 80th Ave (lag) 8.07 0.89 33 +/-0.32 7.75 8.39
Wadsworth Bl / 88th Ave (lag) 7.79 0.68 39 +/-0.22 7.62 8.01
Both Lead Sites Combined 8.67 1.54 45 +/-0.46 8.21 9.13
Both Lao Sites Combined 7.92 1.08 72 +/-0.25 7.67 8.17
Difference between 4th vehicle crossing time for the combined sites is significant at the 95% level.
27


4.0 Accident Analysis
Accident data was collected for a three year period from May of 1995
through April of 1998. Consideration was given to analyzing a five year
period however, due to several construction projects along Wadsworth Blvd
during the period from 1994 to 1995, accident data was analyzed for this
more stable three year period between mid 1995 and mid 1998. The
construction projects involved adding left-turn lanes and speed change
lanes. One project involved extensive vertical alignment shifts for a railroad
underpass as well as intersection improvements at 64th Ave. In addition to
these capacity improvements, the signal phasing at the Wadsworth Blvd and
64th Ave intersection was changed from protected/permitted left-turn
phasing to protected-only with the completion of the latest project.
Conversations with CDOT verified that the current configuration of lead/lag
signal phasing has virtually remained unchanged in the past three years.
The date and times of the accidents were obtained so that accidents that did
not occur during the period of the day that did not have a lead/lag phasing
would be discounted. Collision diagrams were constructed from the accident
data at each of the six intersections
28


Daily traffic volumes for left-turns and through traffic on Wadsworth Blvd.
were estimated at each intersection so that accident rates and measures of
exposure could be calculated for the left-turn movements. Various peak
hour turning movement counts were used from 1993 to 1995 and factored to
obtain the daily and yearly traffic volumes for the through traffic and the left-
turn traffic. Peak hour volumes were divided by a factor of 0.10 to convert
peak hour traffic to average daily traffic. Information obtained from CDOT for
Wadsworth Blvd. shows that approximately 10% of the daily traffic occurs in
the peak hour.
The accident rates shown in Table 3 are normalized accidents per million
left- turn vehicles. All six intersection accident rates were averaged for the
lead and lag left-turn movements. Based upon the provided signal timings,
each intersection reverts to free operations and the lead/lag phasing is
dropped after 10 P.M. until 6 A.M. Any accidents occurring during these
hours were dropped from the data. The results show in the table show the
lagging left turn movement accident rates are lower than the leading left turn
movement.
A test for statistical significance was performed on the mean accident rates
29


for leading and lagging left turns. A two-sample t-procedure assuming
unequal variances was used to test the difference between the means and is
defined as follows(6):
Given two populations A and B,
Population A
n = sample size
x = sample mean
sx = sample standard deviation
fjA = population mean
Population B
m = sample size
y- sample mean
sy = sample standard deviation
= population mean
30


The t-statistic for the null hypothesis H0: fJA- jjB= 5 is
t
x-y-d
N
2 2
S S
* y
n m
(4)
Where the degrees of freedom of the critical point are
2 2
s s
(+JL)2
n m
n 2(n -1) m 2(m -1)
(5)
31


The null hypothesis was tested at the 95th percentile level with the absolute
value of t compared to t^2 v (6). The results for lead left-turn accident rates
and lag left-turn accident rates are shown in Table 3. The results show that
the accident rates for lag left-turns and lead left-turns are not significantly
different at the 95th percentile level. That is the null hypothesis is rejected.
The relatively large (greater than 0.10) p-value also supports this conclusion
It is interesting to note, however, that the lag left-turn accident rate is lower
than the lead left-turn accident rate.
32


TABLE 3
Left-Turn Accident Rates along Wadsworth Blvd.
1995 to 1998
Number of Left-turn Volume Accident rate
Intersection Accidents Lag (vehicles/day) (per million turns)
______________LEAD LAG Direction LEAD LAG LEAD LAG
52NDAVE. 11 5 southbound 4000 1000 2.51 4.57
53RDAVE. 9 4 southbound 4000 1000 2.05 3.65
55TH AVE. 2 2 northbound 500 600 3.65 3.04
64THAVE. 7 2 northbound 1000 400 6.39 4.57
68TH AVE. 3 1 northbound 500 1000 5.48 0.91
80TH AVE. 3 6 northbound 3000 4000 0.91 1.37
Sum 21.00 18.11
Mean 3.50 3.02
StdDev 2.10 1.57
Statistical Comparison of Mean rates
n=m= 6
t- statistic = 0.448
v= 9.25
Critical t (0.025/ 9.25) = 2.254
p-value = 0.74
33


Accident records were further sorted by the following three categories of
accident types so as to analyze patterns of accidents. The categories
shown in Table 4 are:
1. Left-turn collisions with oncoming traffic
2. Left-turn collisions with cross traffic (right angle collisions)
3. Any other left-turn accidents from Wadsworth Blvd to the cross
street.
The majority of left-turn accidents occurred with oncoming traffic. This was
true for both lead and lag left-turn movements. The data does however
show a higher proportion of accidents with oncoming traffic for the lead left-
turn movements.
The original police reports sometimes provide additional useful information
and diagrams of the accidents. The police reports were available for a
portion of the three year study period from July 1996 to May 1998. These
reports were reviewed to determine the possible causes of the accidents as
well as any citations that were issued. Table 5 shows the results of the
police reports broken out by type of accident.
34


TABLE 4
Left-Tum Accident Types along Wadsworth Blvd.
1995 to 1998
Intersection Number of Accidents LEAD LAG Lag Direction Accidents by type oncoming right angle other LEAD LAG LEAD LAG LEAD LAG
52ND AVE. 11 5 southbound 9 4 0 0 2 1
53RD AVE. 9 4 southbound 9 4 0 0 0 0
55TH AVE. 2 2 northbound 2 0 0 0 0 2
64THAVE. 7 2 northbound 5 2 2 0 0 0
68TH AVE. 3 1 northbound 3 1 0 0 0 0
80TH AVE. 5 6 northbound 3 2 1 2 1 2
Sum by type 37 20 31 13 3 2 3 5
Percent of Total 84% 65% 8% 10% 8% 25%
Other accidents include loss of control due to weather, sideswipes, and rear end accidents
35


TABLES
Left-Turn Accident Causes along Wadsworth Blvd
1995 to 1998
Intersection Type of Accident Cause/ Violation
Laa Left Turns
52nd Ave oncoming oncoming oncoming left turn ran red arrow violation through red light violation left turn ran red arrow violation
53rd Ave oncoming oncoming left turn ran red arrow violation through red light violation
55th Ave other other left turn sideswipe unsafe lane change left turn sideswipe avoid stopped truck
64th Ave oncoming left turn failed to yield
80th Ave other oncoming oncoming right angle left turn rear end through red light violation through lost control left turn lost control, icy conditions
Lead Left Turns
52nd Ave other oncoming oncoming other Side swipe / rear end (both left turns) left turn red arrow violation left turn red arrow violation Rear end (both left turns)
53rd Ave oncoming oncoming oncoming oncoming oncoming oncoming oncoming left turn red arrow violation left turn red arrow violation left turn red arrow violation Through red light violation Through red light violation left turn failed to yield left turn red arrow violation
64th Ave oncoming oncoming oncoming oncoming left turn failed to yield left turn red arrow violation left turn red arrow violation left turn red arrow violation
68th Ave oncoming left turn failed to yield
80th Ave right angle oncoming Sb-Eb left turn collided w/ Wb-Sb left turn left turn red arrow violation
36


The sample of data show higher left-turn red arrow violations with the lead
left-turn traffic than with the lag left-turn traffic. Of the 15 lead left-turn
accidents with oncoming traffic, only two were not a result of either a left-turn
arrow violation or left-turn failing to yield. The 8 lag left-turn accidents with
oncoming traffic were split with 4 accidents due to left turn arrow violations
and 4 accidents due to the through traffic running the red light. The
remaining lag left-turn accidents were due to improper lane changes and
drivers losing control of their vehicles. The remaining lead left-turn accidents
were rear end and sideswipe accidents possibly due to inattentiveness or
unknown reasons.
These differences could be attributed to the inherent sequence of lag and
lead left turns. The lag left-turner would collide with oncoming traffic if the
turn was made before the left-turn arrow came on or if the oncoming through
traffic was running the red light at the end of its phase. The chances of the
latter occurring perhaps are greater since the momentum of the through
opposing movement would be greater. At the end of the left turn phase, the
left-turn arrow violation would more than likely result in an accident with
cross traffic although, this pattern was not observed. One possible
explanation is that all of these intersections have cross street lead left-turn
37


phases. This means that traffic running the red arrow at the end of the
phase would encounter cross street left-turn traffic that was moving slower
and perhaps more visible and thus more able to avoid an accident.
The lead left-turner would collide with cross traffic at the beginning of the
phase due to a cross street red light violation. This again was not observed.
The red arrow violation and collision with oncoming traffic would happen at
the end of the lead left-turn phase. This pattern was observed. A collision
between lead left-turn traffic running the red arrow would encounter
opposing through traffic traveling at a higher speed and less visible thus,
ultimately allowing less time for a driver to react.
38


5.0 Conclusions
The comparison of traffic flow measures of lead and lag left-turn phasings
indicated that both the mean start-up lost time and fourth vehicle crossing
time were significantly lower for lag left turns. The popular opinion that more
lost time is incurred with the lag left-turn phasing because of driver
expectancy is not supported by the lost time measurements or the measured
fourth vehicle crossing times.
Each of the measured saturation flow rates and the lost times were done at
the afternoon peak hours. This was mainly because of the better chance of
observing heavy enough traffic to obtain good measured saturation flow. It
is likely that the majority of drivers at this time are familiar with the local
signal timings and would be expecting the lead/lag phasing that has been in
place. Even so, the peak hours represent times when signal coordination is
most important for efficient traffic operation. At times of lighter traffic flow,
the lost time incurred by unfamiliar driver is not as critical.
The accident rate comparisons also do not indicate any additional safety
problems related to driver expectancy with lag left-turns versus lead left-
39


turns. It is possible that the sequence of signal phasing of lag left-turns may
make it even less prone to oncoming left-turn accidents since the following
phase is the cross street left-turn phase. Based upon the conditions and
results of this study, the use of protected-only lead/lag left-turn phasing can
improve signal progression and there is no evidence of loss of safety or
capacity.
40


Technical Appendix


42


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Csh 121 & W 52nd Ave


Csh 121 & W 53rd Ave
30 Accidents 05/01/93 04/30/98
eWm97
04/23/1998
Acddents-witfi missing data 10)
44
'1995


Csh 121 &W 55th Ave
9 Accidents 05/01/93 04/30/98
45


Csh 121 & W 64th Ave
30 Accidents 05/01/93 04/30/98


Csh 121 &W 68th Ave
22 Accidents 05/01/93 04/30/98
47


Csh 121 &W 80th Ave
31 Accidents 05/01/93 04/30/98
48


Intersection Magic VER 5.5
City of Arvada, CO 11/05/1998
Accident listing
05/01/1993 04/30/1998
CSH 121 & W 52ND AVE
Sorted by
TIME VEH 1 DIR VEH 2 DIR VEH : L MOV VEH 2 MOV DATE
12:30 WEST WEST Left turn Left turn 10/22/1993
19 : 08 NORTH WEST Left turn Parked 10/27/1993
14:30 SOUTH NORTH Left turn Straight 03/02/1994
16:20 SOUTH NORTH Left turn Straight 07/30/1994
11:25 SOUTH NORTH Straight Left turn 08/22/1994
9:30 SOUTH NORTH Left turn Straight 08/26/1994
13:45 SOUTH NORTH Left turn Straight 09/07/1994
18:30 EAST EAST Stopped Left turn 09/15/1994
3:07 NORTH Left turn 10/14/1994
19:55 WEST EAST Left turn Straight 02/25/1995
17:00 NORTH- -WES SOUTH Left turn Straight 03/30/1995
10:26 WEST WEST Left turn Straight 05/06/1995
13:02 SOUTH NORTH Left turn Straight 06/07/1995
21:30 SOUTH NORTH-WES Straight Left turn 06/08/1995
11:05 NORTH- -WES SOUTH Left turn Straight 06/19/1995
15:50 NORTH SOUTH Left turn Straight 07/22/1995
14 : 05 SOUTH- NORTH Left turn Straight 08/18/1995
17:10 NORTH NORTH Left turn Left turn 08/20/1995
14:30 SOUTH SOUTH Left turn Stopped 10/22/1995
11:05 NORTH SOUTH Left turn Straight 01/02/1996
9:30 NORTH SOUTH Left turn Straight 03/06/1996
22:43 WEST EAST Left turn Straight 05/03/1996
13:30 WEST SOUTH Left turn Straight 06/26/1996
9:14 SOUTH NORTH Left turn Straight 07/23/1996
12:58 NORTH SOUTH Left turn Straight 08/10/1996
17:15 NORTH NORTH Left turn Left turn 08/20/1996
10:20 NORTH SOUTH Left turn Straight 09/02/1997
12:20 EAST EAST Left turn Left turn 10/21/1997
15:55 WEST EAST Left turn Straight 10/23/1997
12:20 SOUTH NORTH Left turn Straight 11/14/1997
12:30 NORTH SOUTH Left turn Starting 12/31/1997
14:53 WEST EAST Left turn Straight 04/12/1998
49


Intersection Magic VER 5.5
City of Arvada, CO 11/05/1998
Accident listing
05/01/1993 04/30/1998
CSH 121 & W 53RD AVE
Sorted by
TIME VEH 1 DIR VEH 2 DIR VEH 1 MOV VEH 2 MOV DATE
7:45 NORTH SOUTH Left turn Straight 09/16/1993
13:40 SOUTH NORTH Straight Left turn 10/07/1993
7:20 NORTH SOUTH Left turn Straight 12/16/1993
5:07 NORTH SOUTH Left turn Straight 02/28/1994
17:10 NORTH -WES SOUTH Left turn Straight 03/09/1994
11:40 NORTH- -WES SOUTH Left turn Straight 04/26/1994
23:00 NORTH SOUTH Left turn Straight 07/12/1994
22:25 NORTH SOUTH Straight Left turn 09/02/1994
15:30 SOUTH NORTH Straight Left turn 09/22/1994
10:05 NORTH SOUTH Left turn Straight 11/05/1994
13:22 SOUTH NORTH- -WES Straight Left turn 12/20/1994
11:49 NORTH SOUTH Left turn Straight 12/28/1994
20:29 NORTH SOUTH 'Left turn Straight 12/30/1994
19:30 NORTH SOUTH Left turn Straight 01/18/1995
15:16 SOUTH NORTH Straight Left turn 02/02/1995
8:40 SOUTH NORTH Left turn Straight 05/16/1995
14:50 NORTH SOUTH- EAS Straight Left turn 06/09/1995
16:20 SOUTH NORTH Straight Left turn 11/28/1995
11:10 NORTH SOUTH Left turn Straight 03/09/1996
19:10 NORTH SOUTH Left turn Straight 07/19/1996
9:30 NORTHt WES SOUTH Left turn Straight 08/15/1996
19:31 SOUTH NORTH Left turn Straight 09/07/1996
11:10 NORTH SOUTH Left turn Straight 10/13/1996
11:40 NORTH SOUTH Straight Left turn 10/28/1996
1:28 SOUTH NORTH Straight Left turn 01/19/1997
15:00 NORTH SOUTH Left turn Straight. 01/24/1997
20:05 EAST WEST Left turn Straight 04/07/1997
19:45 SOUTH NORTH- WES Straight Left turn 07/14/1997
6:20 NORTH SOUTH Left turn Straight 12/24/1997
17:57 WEST EAST Left turn Straight 04/23/1998
50


Intersection Magic VER 5.5
City of Arvada, CO 11/05/1998
Accident listing
05/01/1993 04/30/1998
CSH 121 & W 55TH AVE
Sorted by
TIME VEH 1 DIR VEH 2 DIR VEH 1 MOV VEH 2 MOV DATE
14:48 NORTH WEST
7:57 WEST EAST
10:15 SOOTH NORTH
22:40 NORTH SOOTH
22:10 NORTH NORTH
11:00 NORTH NORTH
21:30 EAST WEST
21:00 EAST WEST
9:35 255 255
Straight Left turn 03/01/1994
Left turn Straight 10/25/1994
Left turn Straight 09/19/1995
Straight Left turn 10/13/1995
Left turn Left turn 03/21/1997
Left turn Left turn 04/25/1997
Left turn Straight 09/12/1997
Left turn Straight 11/09/1997
Left turn Left turn 01/17/1998
51


Intersection Magic VER 5.5
City of Arvada, CO 11/05/1998
Accident listing
05/01/1993 04/30/1998
CSH 121 & W 64TH AVE
Sorted by
TIME VEH 1 DIR VEH 2 DIR VEH 1 MOV VEH 2 MOV DATE
13:48 SOUTH NORTH-WES Straight Left turn 05/21/1993
21:15 WEST Left turn 09/10/1993
16:45 NORTH Left turn 12/02/1993
13:00 NORTH SOUTH Straight Left turn 02/22/1994
9:50 SOUTH EAST Straight Left turn 03/27/1994
10 :58 NORTH SOUTH Straight Left turn 04/06/1994
17:00 NORTH SOUTH Left turn Straight 04/11/1994
15:20 SOUTH WEST Backing Left turn 06/30/1994
10:35 NORTH SOUTH Straight Left turn 09/12/1994
11:45 NORTH SOUTH Left turn Straight 12/23/1994
10:55 SOUTH SOUTH Left turn Left turn 02/21/1995
11:15 EAST EAST Left turn Left turn 03/29/1995
18:20 EAST SOUTH Left turn Straight 05/08/1995
13:20 SOUTH NORTH Straight Left turn 08/20/1995
16:21 EAST SOUTH-EAS Left turn Left turn 10/10/1995
9:55 north EAST Straight Left turn 10/13/1995
12:30 NORTH WEST Straight Left turn 11/22/1995
9:00 SOUTH EAST Straight Left turn 12/01/1995
5:25 EAST SOUTH Left turn-Straight 03/23/1996
17:55 SOUTH NORTH Left turn Straight 06/15/1996
17 :10 NORTH SOUTH Straight Left turn 07/01/1996
14:30 SOUTH ' EAST Straight Left turn 08/03/1996
8:19 EAST EAST Left turn Left turn 08/30/1996
16:31 SOUTH EAST Straight Left turn 09/17/1996
8:40 SOUTH EAST Left turn Left turn 01/28/1997
11:55 SOUTH NORTH Left turn Straight 02/18/1997
14:57 SOUTH NORTH Left turn Straight 02/27/1997
12:12 SOUTH NORTH Left turn Straight 03/18/1997
14:45 NORTH-WES SOUTH Left turn Straight 04/23/1997
18:35 SOUTH EAST Straight Left turn 08/11/1997
52


Intersection Magic VER 5.5
City of Arvada, CO 11/05/1998
Accident listing
05/01/1993 04/30/1998
CSH 121 & W 68TH AVE
Sorted by
TIME VEH 1 DIR VEH 2 DIR VEH 1 MOV VEH 2 MOV DATE
16:30 NORTH WEST Straight Left turn 10/05/1993
15:23 SOUTH EAST Straight Left turn 11/04/1993
13:16 NORTH WEST Straight Left turn 01/03/1994
15:40 NORTH WEST- Straight Left turn 01/20/1994
14:11 SOUTH-EAS NORTH Left turn Straight 02/27/1994
7:10 NORTH EAST Straight Left turn 03/14/1994
12:55 NORTH SOUTH Left turn Straight 06/18/1994
18:10 NORTH SOUTH Left turn Straight 08/12/1994
20:05 WEST EAST Left turn Straight 08/26/1994
7:31 NORTH- SOUTH Left turn Straight 09/28/1994
19:15 EAST WEST Left turn Straight 01/12/1995
10:15 WEST NORTH Left turn Straight 02/20/1995
17:20 EAST WEST Left turn 08/15/1995
14:35 WEST EAST Straight Left turn 03/18/1996
15:15 NORTH SOUTH Straight Left turn 05/10/1996
13:50 SOUTH NORTH Left turn Straight 05/12/1996
17:17 EAST WEST Left turn Straight 09/24/1996
16:40 SOUTH-EAS NORTH Left turn Straight 03/21/1997
20:35 EAST WEST Left turn Straight 03/21/1997
7:50 EAST WEST Left turn Straight 06/04/1997
17:30 SOUTH NORTH Straight Left turn 06/17/1997
17:03 EAST WEST Left turn Straight 09/08/1997
53


Intersection Magic VER 5.5
City of Arvada, CO 11/05/1998
Accident listing
05/01/1993 04/30/1998
CSH 121 Sc W 80TH AVE
Sorted by
TIME VEH 1 DIR VEH 2 DIR VEH ; 1 MOV VEH 2 MOV DATE
13:15 NORTH. NORTH Left turn Stopped 07/02/1993
20:05 EAST WEST Left turn Straight 07/23/1993
9:50 SOUTH Left turn 08/26/1993
14:50 NORTH NORTH Left turn Left turn 11/29/1993
4:40 WEST NORTH Left turn Straight 12/14/1993
18:00 SOUTH NORTH Left turn Straight 02/11/1994
11:50 WEST WEST Left turn Left turn 05/01/1994
7:48 NORTH SOUTH Left turn Straight 06/02/1994
9:00 EAST EAST Left turn Left turn 06/24/1994
15:55 SOUTH EAST Left turn Straight 09/27/1994
15:50 NORTH WEST Left turn Straight 03/06/1995
21:01 SOUTH-EAS NORTH Left turn Straight 04/26/1995
7:25 NORTH SOUTH Straight Left turn 05/13/1995
19:00 NORTH WEST Straight Left turn 05/17/1995
17:49 WEST EAST Straight Left turn 06/01/1995
22:17 EAST EAST Left turn Left turn 06/30/1995
13 :25 SOUTH SOUTH Left turn Left turn 07/03/1995
21:30 NORTH NORTH Left turn Left turn 01/25/1996
12:25 NORTH NORTH Left turn Left turn 04/28/1996
7:00 WEST EAST Straight Left turn 05/22/1996
22:30 SOUTH WEST Left turn Left turn 08/01/1996
17:50 SOUTH NORTH Straight Left turn 08/14/1996
99:99 EAST EAST Left turn Left turn 10/04/1996
14:10 WEST WEST Left turn Left turn 12/20/1996
19:00 EAST . Left turn 01/02/1997
14:05 EAST EAST Left turn Left turn 01/09/1997
15:55 SOUTH NORTH-WES Straight Left turn 01/21/1997
16:54 NORTH-WES EAST Left turn Stopped 02/05/1997
17:20 NORTH NORTH Left turn Left turn 05/08/1997
16:00 NORTH EAST Straight Left turn 07/02/1997
22:37 SOUTH NORTH Left turn Straight 10/23/1997
54


W4IKS Table 7 Sheet 1
Date; Monday, April 20, 1998 Time: 09:24 AM
Intersection #055 SH 121 @ W 52nd Ave
(B+PLAN+KEY)
FUNCTION KEY Plan 1 Plan 2 Plan 3
Cycle Length 0 100 100 100
Forceoff 01 1 14 13 13
Forceoff 02 2 0 0 0
Forceoff 03 3 34 27 32
Forceoff 04 4 58 44 47
Forceoff 05 5 69 58 63
Forceoff 06 6 0 0 0
Forceoff 07 7 26 27 26
Forceoff 08 8 58 44 47
Offset 9 4 8 59
Perm Length A 1 1 1
Max Dwell B 34 34 34
Lead Phases C 23 5 7 23 5 7 23 5 7
Coord Phases D 2 6 2 6 2 6
Perm 2 Phases E
Min Recall F
Plan 4 Plan 5
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
Plan 6 Plan 7
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
Plan 8 Plan 9
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0


W4IKS Table 5 Sheet 1
Date: Monday, April 20, 1998 Time: 09:24 AM
Intersection #055 SH 121 0 W 52nd Ave
(A+CODE)
EVENT 1234567 HR MIN FUNC CODE
1 23456 5 0 1 80-83
2 23456 6 0 2 84-87
3 23456 9 0 1 88-8B
4 23456 15 0 3 8C-8F
5 23456 19 0 1 90-93
6 1234567 22 0 20 94-97
7 1234567 22 1 129 98-9B
8 23456 4 59 128 9C-9F
9 1 7 5 59 128 A0-A3
10 1 7 6 0 1 A4-A7
11 7 10 0 3 A8-AB
12 1 12 0 3 AC-AF
13 1 7 18 0 1 B0-B3
14 0 0 0 B4-B7
15 0 0 0 B8-BB
16 0 0 0 BC-BF
EVENT 1234567 HR MIN FUNC CODE
17 0 0 0 CO.-C3
18 0 0 0 C4-C7
19 0 0 0 C8-CB
20 0 0 0 CC-CF
21 0 0 0 D0-D3
22 0 0 0 D4-D7
23 0 0 0 D8-DB
24 0 0 0 DC-DF
25 0 0 0 E0-E3
26 0 0 0 E4-E7
27 0 0 0 E8-EB
28 0 0 0 EC-EF
29 0 0 0 F0-F3
30 0 0 0 F4-F7
31 0 0 0 F8-FB
32 0 0 0 FC-FF


W4IKS Table 1 Page 0
Date; Monday, April 20, 1998 Time : 09:23 AM
Intersection #055 SH 121 @ W 52nd Ave
(0+KEY) (PHASE+KEY)
FUNCTIONS KEY 12345678 FUNCTIONS
Veh Recall 0 Max I
Ped Recall 1 Max II
Red Lock 2 13 5 7 Walk
Yellow Lock 3 Flash DW
Permit 4 12345678 Max Initial
Ped Phases 5 2 4 6 8 Min Green
Lead-Phases 6 13 5 7 TBR
Double Entry 7 TTR
Sequential Timing 8 Observe Gap
Startup Green 9 Passage
Overlap A A 5 Min Gap
Overlap B B Added Actuation
Overlap C C Yellow
Overlap D D Red Clear
Exclusive E Red Revert
Simultaneous Gap F Walk II
SBLT NB WBLT EB NBLT SB EBL'
KEY PHI PH2 PH3 PH4 PH5 PH6 PH7
0 8 25 15 18 18 25 15
1 8 20 10 14 14 20 10
2 0 4 0 4 0 4 0
3 0 11 0 18 0 11 0
4 0 0 0 0 0 0 0
5 4 5 4 4 4 5 4
6 0 0 0 0 0 0 0
7 0 0 0 0 0 0 0
8 0.0 0.0 0.0 0.0 0.0 0.0 0.0
9 1.5 5.0 1.5 1.5 1.5 5.0 1.5
A 1.5 5.0 1.5 1.5 1.5 5.0 1.5
B 0.0 0.0 0.0 0.0 0.0 0.0 0.0
C 3.0 4.0 3.0 3.0 3.0 4.0 3.0
D 2.0 2.0 2.0 2.0 2.0 2.0 2.0
E 0.0 0.0 0.0 0.0 0.0 0.0 0.0
F 0 0 0 0 0 0 0
PH8
18
14
4
18
0
ooooocncnooo.fi>


Ol
oo
W4XKS Table 7 Sheet 1
Date: Monday, April 20, 1998 Time: 09:23 AM
Intersection #054 SH 121 0 W 53rd Ave
(B+PLAN+KEY)
FUNCTION KEY Plan 1 Plan 2 Plan 3
Cycle Length 0 100 100 100
Forceoff 01 1 18 13 13
Forceoff 02 2 0 0 0
Forceoff 03 3 30 26 26
Forceoff 04 4 45 41 41
Forceoff 05 5 63 57 60
Forceoff 06 6 0 0 0
Forceoff 07 7 30 26 26
Forceoff 08 8 45 41 41
Offset 9 45 23 97
Perm Length A 1 1 1
Max Dwell B 34 34 34
Lead Phases C 23 5 7 23 5 7 23 5 7
Coord Phases D 2 6 2 6 2 6
Perm 2 Phases E
Min Recall F
Plan 4 Plan 5 Plan 6
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
Plan 7 Plan 8 Plan 9
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0


W4IKS Table 5 Sheet 1
Date: Monday, April 20, 1998 Time: 09:23 AM
Intersection #054 SH 121 0 W 53rd. Ave
(A+CODE)
EVENT 1234567 HR MIN FUNC CODE
1 23456 5 0 1 80-83
2 23456 6 0 2 84-87
3 23456 9 0 1 88-8B
4 23456 15 0 3 8C-8F
5 23456 19 0 1 90-93
6 1234567 22 0 20 94-97
7 1234567 22 1 129 98-9B
8 23456 4 59 128 9C-9F
9 1 7 5 59 128 AO-A3
10 1 7 6 0 1 A4-A7
11 7 10 0 3 A8-AB
12 1 12 0 3 AC-AF
13 1 7 18 0 1 B0-B3
14 0 0 0 B4-B7
15 0 0 0 B8-BB
16 0 0 0 BC-BF
EVENT 1234567 HR MIN FUNC CODE
17 0 0 0 CO-C3
18 0 0 0 C4-C7
19 0 0 0 C8-CB
20 0 0 0 CC-CF
21 0 0 0 D0-D3
22 0 0 0 D4-D7
23 0 0 0 D8-DB
24 0 0 .0 DC-DF
25 0 0 0 E0-E3
26 0 0 0 E4-E7
.27 0 0 0 E8-EB
28 0 0 0 EC-EF
29 0 0 0 F0-F3
30 0 0 0 F4-F7
31 0 0 0 F8-FB
32 0 0 0 FC-FF


W4IKS Table 1 Page 0
Date: Monday, April 20, 1998 Time: 09:23 AM
Intersection #054 SH 121 6 W 53rd Ave
(0+KEY) (PHASE+KEY)
FUNCTIONS KEY 12345678 FUNCTIONS
Veh Recall 0 Max I
Ped Recall 1 Max II
Red Lock 2 1 5 Walk
Yellow Lock 3 Flash DW
Permit 4 12345678 Max Initial
Ped Phases 5 2 4 6 8 Min Green
Lead Phases 6 13 5 7 TBR
Double Entry 7 TTR
Sequential Timing 8 Observe Gap
Startup Green 9 Passage
Overlap A A Min Gap
Overlap B B Added Actuation
Overlap C C Yellow
Overlap D D Red Clear
Exclusive E Red Revert
Simultaneous Gap F Walk II
SBLT NB WBLT EB NBLT SB EBLT WB
KEY PHI PH2 PH3 PH4 PH5 PH6 PH7 PH8
0 12 25 10 15 22 25 10 15
1 8 20 8 14 14 20 8 14
2 0 4 0 4 0 4 0 4
3 0 18 0 26 0 18 0 26
4 0 0 0 0 0 0 0 0
5 3 5 3 4 3 5 3 4
6 0 0 0 0 0 0 0 0
7 0 0 0 0 0 0 0 0
8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
9 1.5 5.0 1.5 1.5 1.5 5.0 1.5 1.5
A 1.5 5.0 1.5 1.5 1.5 5.0 1.5 1.5
B 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
C 3.0 4.0 3.0 3.0 3.0 4.0 3.0 3.0
D 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0
E 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
F 0 0 0 0 0 0 0 0


W4IKS Table 7 Sheet 1
Date.: Monday, April 20, 1998 Time: 09:21 1
Intersection #053 SH 121 @ W 55th Ave
(B+PLAN+KEY)
FUNCTION KEY Plan 1 Plan 2 Plan 3
Cycle Length 0 100 100 100
Forceoff 01 1 38 40 40
Forceoff 02 2 0 0 0
Forceoff 03 3 0 0 0
Forceoff 04 4 27 28 28
Forceoff 05 5 11 12 12
Forceoff 06 6 0 0 0
Forceoff 07 7 0 0 0
Forceoff 08 8 27 28 28
Offset 9 39 9 82
Perm Length A 1 1 1
Max Dwell B 34 34 34
Lead Phases C 13 67 1 3 67 1 3 67
Coord Phases D 2 6 2 6 2 6
Perm 2 Phases E
Min Recall F
Plan 4 Plan 5
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
Plan 6 Plan 7
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
Plan .8 Plan 9
0 0
0 0
0 0
0 0
0 0
0 O'
0 0
0 0
0 0
0 0
0 0
0 0


W4IKS Table 5 Sheet 1
Date: Monday, April 20, 1998 Time: 09:21 AM
intersection #053 SH 121 @ W 55th Ave
(A+CODE)
EVENT 1234567 HR MIN FUNC CODE
1 23456 5 0 1 80-83
2 23456 6 0 2 84-87
3 23456 9 0 1 88-8B
4 23456 15 0 3 8C-8F
5 23456 19 0 1 90-93
6 1234567 22 0 20 94-97
7 1234567 22 1 129 98-9B
8" 23456 4 59 128 9C-9F
9 1 7 5 59 128 AO-A3
10 1 7 6 0 1 A4-A7
11 7 10 0 3 A8-AB
12 1 12 0 3 AC-AF
13 1 7 18 0 1 B0-B3
14 0 0 0 B4-B7
15 0 0 0 B8-BB
16 0 0 0 BC-BF
<
EVENT 1234567 HR
17 0
18 0
19 0
20 .0
21 0
22 0
23 0
24 0
25 0
26 0
27 0
28 0
29 0
30 0
31 1234567 5
32 1234567 22
MIN FUNC CODE
0 0 CO-C3
0 0 C4-C7
0 0 C8-CB
0 0 CC-CF
0 0 D0-D3
0 0 D4-D7
0 0 D8-DB
0 0 DC-DF
0 0 E0-E3
0 0 E4-E7
0 0 E8-EB
0 0 EC-EF
0 0 F0-F3
0 0 F4-F7
0 131 F8-FB
0 132 FC-FF


05
CO
W4IKS Table 1 Page 0
Date: Monday, April 20, 1998 Time: 09:21 AM
Intersection #053 SH 121 0 W 55th Ave
(0+KEY)
FUNCTIONS KEY 12345678
Veh Recall 0
Ped Recall 1
Red Lock 2 1 5
Yellow Lock 3
Permit 4 12 456 8
Ped Phases 5 2 8
Lead Phases 6 13 5 7
Double Entry 7 1 1 oo|
Sequential Timing 8
Startup Green 9
Overlap A A
Overlap B B
Overlap C C
Overlap D D
Exclusive E
Simultaneous Gap F
(PHASE+KEY) FUNCTIONS KEY SBL PHI
Max I 0 12
Max II 1 8
Walk 2 0
Flash DW 3 0
Max Initial 4 0
Min Green 5 3
TBR 6 0
TTR 7 0
Observe Gap 8 0.0
Passage 9 1.5
Min Gap A 1.5
Added Actuation B 0.0
Yellow C 3.0
Red Clear D 2.0
Red Revert E 0.0
Walk II F 0
NB EB NBLT SB WB
PH2 PH3 PH4 PH5 PH6 PH7 PH8
25 0 18 8 25 0 18
20 0 14 8 20 0 14
4 0 4 0 4 0 4
13 0 26 0 13 0. 26
0 0 0 0 0 0 0
5 0 4 3 5- 0 4
0 0 4 0 0 0 0
0 0 0 0 0 0 0
0.0 0.0 0.0 0.0 0.0 0.0 0.0
5.0 0.0 1.5 1.5 5.0 0.0 1.5
5.0 0.0 1.5 1.5 5.0 0.0 1.5
0.0 0.0 0.0 0.0 0.0 0.0 0.0
4.0 0.0 3.0 3.0 4.0 0.0 3.0
2.0 0.0 2.0 2.0 2.0 0.0 2.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0
0 0 0 0 0 0 0


W4IKS Table 5 Sheet 1
Date: Monday, April 20, 1998 Time: 09:15 AM
Intersection #049 SH 121 @ W 68th
(A+CODE)
EVENT 1234567 HR MIN FUNC CODE
1 23456 5 0 1 80-83
2 23456 6 0 2 84-87
3 23456 9 0 1 88-8B
4 23456 15 0 3 8C-8F
5 23456 19 0 1 90-93
6 1234567 22 0 20 94-97
7 1234567 22 1 129 98-9B
8 23456 4 59 128 9C-9F
9 1 7 5 59 128 A0-A3
10 1 7 6 0 1 A4-A7
11 7 10 0 3 A8-AB
12 1 12 0 3 AC-AF
13 1 7 18 0 1 B0-B3
14 0 0 0 B4-B7
15 0 0 0 B8-BB
16 0 0 0 BC-BF
EVENT 1234567
17
18
19
20
21
22
23
24
25
26
.27 ________
28
29
30
31
32
MIN FUNC CODE
0 0 CO-C3
0 0 C4-C7
0 0 C8-CB
0 0 CC-CF
0 0 D0-D3
0 0 D4-D7
0 0 D8-DB
0 0 DC-DF
0 0 E0-E3
0 0 E4-E7
0 0 E8-EB
0 0 EC-EF
0 0 F0-F3
0 0 F4-F7
0 0 F8-FB
0 0 FC-FF
HR
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0


W4ZKS Table 1 Page 0
Date: Monday, April 20, 1998 Time : 09:15 AM
Intersection #049 SH 121 Q W 68th
(0+KEY) (PHASE+KEY)
FUNCTIONS KEY 12345678 FUNCTIONS
Veh Recall 0 Max I
Ped Recall 1 Max IX
Red Lock 2 145 8 Walk
Yellow Lock 3 Flash DW
Permit 4 12345678 Max Initial
Ped Phases 5 2 4 6 8 Min Green
Lead Phases 6 13 5 7 TBR
Double Entry 7 4 8 TTR
Sequential Timing 8 Observe Gap
Startup Green 9 Passage
Overlap A A 5 Min Gap
Overlap B B Added Actuation
Overlap C C Yellow
Overlap D D Red Clear
Exclusive E Red Revert
Simultaneous Gap F Walk II
i
SBLT NB WBLT
KEY PHI PH2 PH3
0 8 25 12
1 8 20 8
2 0 4 0
3 0 12 0
4 0 0 0
5 3 5 3
6 0 0 0
7 0 0 0
8 0.0 0.0 0.0
9 1.5 5.0 1.5
A 1.5 5.0 1.5
B 0.0 0.0 0.0
C 3.0 4.0 3.0
D 2.0 2.0 2.0
E 0.0 0.0 0.0
F 0 0 0
NBLT SB EBLT VJB
PH5 PH6 PH7 PH8
12 25 10 20
8 20 8 15
0 4 0 4
0 11 0 23
0 0 0 0
3 5 3 4
0 0 0 0
0 0 0 0
0.0 0.0 0.0 0.0
1.5 5.0 1.5 1.5
1.5 5.0 1.5 1.5
0.0 0.0 0.0 0.0
3.0 4.0 3.0 3.0
2.0 2.0 2.0 2.0
0.0 0.0 0.0 0.0
0 0 0 4
EB
PH4
20
15
4
20
0
4
0
0
0.0
1.5
1.5
0.0
3.0
2.0
0.0
4


W4IKS Table 7 Sheet 1
Date: Monday, April 20, 1998 Time: 09: : 19 AM
Intersection #046 SH 121 @ W 80th
(B+PLAN+KEY)
FUNCTION KEY Plan 1 Plan 2 Plan 3
Cycle Length 0 100 100 100
Forceoff 01 1 67 62 77
Forceoff 02 2 0 0 0
Forceoff 03 3 30 26 32
Forceoff 04 4 53 49 64
Forceoff 05 5 15 13 18
Forceoff 06 6 0 0 0
Forceoff 07 7 33 28 38
Forceoff 08 8 53 49 64
Offset 9 81 66 30
Perm Length A 1 1 1
Max Dwell B 34 34 34
Lead Phases C 1 3 67 1 3 67 1 3 67
Coord Phases D 2 6 2 6 2 6
Perm 2 Phases E
Min Recall F
Plan 4 Plan 5 Plan 6
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0, 0 0
0 0 0
0 0 0
0 0 0
Plan 7 Plan 8 Plan 9
0 0, 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0


W4IKS Table 5 Sheet 1
Date: Monday, April 20, 1998 Time: 09:19 AM
Intersection #046 SH 121 @ W 80th
(A+CODE)
EVENT 1234567 HR MIN FUNC CODE
1 23456 5 0 1 80-83
2 23456 6 0 2 84-87
3 23456 9 0 1 88-8B
4 23456 15 0 3 8C-8F
5 23456 19 0 1 90-93
6 1234567 22 0 20 94-97
7 1234567 22 1 129 98-9B
8 23456 4 59 128 9C-9F
9 ' 1 7 5 59 128 A0-A3
10 1 7 6 0 1 A4-A7
11 7 10 0 3 A8-AB
12 1 12 0 3 AC-AF
13 1 7 18 0 1 B0-B3
14 0 0 0 B4-B7
15 0 0 0 B8-BB
16 0 0 0 BC-BF
EVENT 1234567 HR MIN FUNC CODE
17 0 0 0 CO-C3
18 0 0 0 C4-C7
19 0 0 0 C8-CB
20 0 0 0 CC-CF
21 0 0 0 D0-D3
22 0 0 0 D4-D7
23 0 0 0 D8-DB
24 0 0 0 DC-DF
25 0 0 0 E0-E3
26 0 0 0 E4-E7
27 0 0 0 E8-EB
28 0 0 0 EC-EF
29 0 0 0 F0-F3
30 0 0 0 F4-F7
31 0 0 0 F8-FB
32 0 0 0 FC-FF


W4IKS Table 1 Page 0
Date: Monday, April 20, 1998 Time: 09:19 AM
Intersection #046 SH 121 0 W 80th
(0+KEY) (PHASE+KEY)
FUNCTIONS KEY 12345678 FUNCTIONS
Veh Recall 0 Max I
Ped Recall 1 Max II
Red Lock 2 1 Walk
Yellow Lock 3 Flash DW
Permit 4 12345678 Max Initial
Ped Phases 5 2 4 6 8 Min Green
Lead Phases 6 13 5 7 TBR
Double Entry 7 4 8 TTR
Sequential Timing 8 Observe Gap
Startup Green 9 Passage
Overlap A A Min Gap
Overlap B B Added Actuation
Overlap C C Yellow
Overlap D D Red Clear
Exclusive E Red Revert
Simultaneous Gap F Walk II
SBLT NB WBLT EB NBLT SB EBLT WB
KEY PHI PH2 PH3 PH4 PH5 PH 6 PH7 PH8
0 22 25 16 30 26 25 18 30
1 12 20 10 18 12 20 10 18
2 0 4 0 4 0 4 0 4
3 0 16 0 20 0 16 0 20
4 0 0 0 0 0 0 0 0
5 3 5 3 4 3 5 3 4
6 0 0 0 0 0 0 0 0
7 0 0 0 0 0 0 0 0
8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
9 1.5 5.0 1.5 1.5 1.5 5.0 1.5 1.5
A 1.5 5.0 1.5 1.5 1.5 5.0 1.5 1.5
B 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
C 4.0 4.0 3.0 3.0 3.0 4.0 3.0 3.0
D 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0
E 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
F 0 0 0 0 0 0 0 0


PARKER AND QUINCY
SATURATION FLOW RATE
SB EB Left Turn 4pm to 5pm 3-11-98
Cycle time of 4th veh time of last veh # vehicles in queue # veh >4 Sat flow headway Prevailing Sat Flow start lost time

1 10.9 21.9 11 7 1.57 2291 4.61
2 9.6 16 9 5 1.28 2813 4.48

4 8 17.7 9 5 1.94 1856 0.24
5 8.5 28.2 15 11 1.79 2010 1.34
6 8.3 15.6 7 3 2.43 1479 -1.43
7 7.1 24.8 14 10 1.77 2034 0.02
8 9.5 25.7 14 10 1.62 2222 3.02
9 8.8 13.5 7 3 1.57 2298 2.53
10 9.2 18.7 10 6 1.58 2274 2.87
11 8.9 23.6 12 8 1.84 1959 1.55
12 8.5 16.7 8 4 2.05 1756 0.30
13 8.1 11.13 6 2 1.52 2376 2.04
14 9.3 19.4 11 7 1.44 2495 3.53


17 8 12.2 7 3 1.40 2571 2.40
18 8.6 20.6 10 6 2.00 1800 0.60
19 7.5 23.2 13 9 1.74 2064 0.52
20 8 27.8 15 11 1.80 2000 0.80
21 9 19.4 9 5 2.08 1731 0.68
22 8.3 16.9 8 4 2.15 1674 -0.30
23 6.9 12.22 7 3 1.77 2030 -0.19
24 9.2 34.25 19 15 1.67 2156 2.52
25 7.9 28.4 16 12 1.71 2107 1.07
26 8.6 16.78 10 6 1.36 2641 3.15
27 10.1 25.03 12 8 1.87 1929 2.64

29 8.2 32.25 18 14 1.72 2096 1.33
30 8.1 19.54 12 8 1.43 2517 2.38
31 8.4 18.16 9 5 1.95 1844 0.59
32 10 26.31 14 10 1.63 2207 3.48
33 7.6 27.7 15 11 1.83 1970 0.29
34 8.5 17.59 9 5 1.82 1980 1.23
Mean 8.59 11.20 1.74 2106 1.61
69


CHAMBERS AND HAMPDEN
SATURATION FLOW RATE .
SB EB Left Turn
4:30pm to 5:30pm 3-13-98
Cycle time of 4th veh time of last veh # vehicles in queue # veh >4 Sat flow headway Prevailing Sat Flow start lost time




4 8.7 13.8 7 3 1.70 2118 1.90
5 8.5 14.5 6 2 3.00 1200 -3.50
6 8.37 12.16 6 2 1.90 1900 0.79
7 9.64 13.18 6 2 1.77 2034 2.56
8 7.45 16.06 8 4 2.15 1672 -1.16
9 9.05 13.81 7 3 1.59 2269 2.70
10 9.09 15.07 7 3 1.99 1806 1.12
11 8 11.27 6 2 1.64 2202 1.46
12 8.49 13.72 7 3 1.74 2065 1.52
13 10.14 17.37 8 4 1.81 1992 2.91
14 9.27 18.88 8 4 2.40 1498 -0.34
15 9.96 13.44 6 2 1.74 2069 3.00
16 8.83 14.96 7 3 2.04 1762 0.66
17 8.56 14.38 7 3 1.94 1856 0.80
18 8.46 13.72 7 3 1.75 2053 1.45


Mean 8.83 6.87 1.94 1900 1.06
70


WADSWORTH AND 80TH AVE.
SATURATION FLOW RATE
NB-WB Left Turn 4:30pm to 5:30pm 4-27-98 Sunny 65 degrees
4:30pm to 5:30pm 4-28-98
Cycle time of 4th veh time of last veh # vehicles, in queue # veh >4 Sat flow headway Prevailing Sat Flow start lost time
1 8.7 12.04 6 2 1.67 2156 2.02
2 8.3 14.79 7 3 2.16 1664 -0.35

4 7.17 13.96 8 4 1.70 2121 0.38
5 7.39 12.56 7 3 1.72 2089 0.50
6 8.02 12.63 7 3 1.54 2343 1.87
7 7.86 12.43 7 3 1.52 2363 1.77
8 8.36 13.06 7 3 1.57 2298 2.09
9 6.34 13.94 8 4 1.90 1895 -1.26
10 7.4 11.03 6 2 1.82 1983 0.14
11 8.11 13.12 7 3 1.67 2156 1.43
12 5.96 9.72 6 2 1.88 1915 -1.56

14 9.27 12.72 6 2 1.73 2087 2.37
15 7.62 11.94 7 3 1.44 2500 1.86
16 9.3 13.94 6 2 2.32 1552 0.02
17 6.89 11.25 6 2 2.18 1651 -1.83
18 7.23 12.31 6 2 2.54 1417 -2.93
19 7.7 11.6 6 2 1.95 1846 -0.10
20 7.74 11.62 6 2 1.94 1856 -0.02
21 8.74 14.53 8 4 1.45 2487 2.95
22 7.58 13.44 7 3 1.95 1843 -0.23
23 8.86 13.46 7 3 1.53 2348 2.73
24 7.8 14.59 8 4 1.70 2121 1.01
25 9.15 14.82 7 3 1.89 1905 1.59
26 9.15 13.66 7 3 1.50 2395 3.14
27 7.7 13.25 6 2 2.78 1297 -3.40
28 9.56 14.69 6 2 2.57 1404 -0.70
29 8.49 13 7 3 1.50 2395 2.48
30 8.49 12.93 6 2 2.22 1622 -0.39
31 7.83 12.94 7 3 1.70 2114 1.02
32 9.83 14.84 7 3 1.67 2156 3.15
33 7.68 12.79 7 3 1.70 2114 0.87
34 8.33 13.47 7 3 1.71 2101 1.48
35 8.46 15.1 8 4 1.66 2169 1.82
Mean 8.07 6.81 1.85 2006 0.68
71


WADSWORTH AND 88TH AVE.
SATURATION FLOW RATE
SB-EB Left Turn 4:30pm to 5:30pm 5-18-98 Sunny 80 degrees
4:30pm to 5:30pm 5-19-98 Cloudy 82 degrees
5:15pm to 6:00pm 6-2-98 Sunny 84 degrees
Cycle time of 4th veh time of last veh # vehicles in queue # veh >4 Sat flow headway Prevailing Sat Flow start lost time
3 7.92 9.84 5 1 1.92 1875 0.24
4 7.71 9.19 5 1 1.48 2432 1.79
5 8.08 9.87 5 1 1.79 2011 0.92
6 9.21 11.19 5 1 1.98 1818 1.29
12 8.21 9.56 5 1 1.35 2667 2.81
14 6.95 8.72 5 1 1.77 2034 -0.13
15 7.92 10.53 5 1 2.61 1379 -2.52
17 7.8 9.34 5 1 1.54 2338 1.64
20 6.77 8.09 5 1 1.32 2727 1.49
21 6.8 9.31 5 1 2.51 1434 -3.24
22 7.17 10.18 6 2 1.51 2392 1.15
23 8.3 10.19 5 1 1.89 1905 0.74
24 7.64 10.49 6 2 1.43 2526 1.94
25 7.99 10.82 6 2 1.42 2544 2.33
29 7.68 9.5 5 1 1.82 1978 0.40
33 6.83 8.34 5 1 1.51 2384 0.79
34 6.34 9.97 6 2 1.82 1983 -0.92
35 7.68 9.82 5 1 2.14 1682 -0.88
36 7.74 9.28 5 1 1.54 2338 1.58
37 7.96 10.66 6 2 1.35 2667 2.56
38 6.64 8.89 5 1 2.25 1600 -2.36
39 9.43 11.12 5 1 1.69 2130 2.67
40 8.14 10.59 5 1 2.45 1469 -1.66
41 7.21 8.92 5 1 1.71 2105 0.37
42 8.92 10.53 5 1 1.61 2236 2.48
43 7.24 9.89 5 1 2.65 1358 -3.36
44 8.05 10.16 5 1 2.11 1706 -0.39
45 8.34 10 5 1 1.66 2169 1.70
46 7.77 9.35 5 1 1.58 2278 1.45
47 7.08 8.44 5 1 1.36 2647 1.64
48 7.93 11.22 6 2 1.65 2188 1.35
49 7.61 10.4 6 2 1.40 2581 2.03
50 8.34 9.97 5 1 1.63 2209 1.82
51 7.21 8.98 5 1 1.77 2034 0.13
52 8.77 11 5 1 2.23 1614 -0.15
53 7.96 9.31 5 1 1.35 2667 2.56
54 7.89 9.69 5 1 1.80 2000 0.69
55 8.05 9.9 5 1 1.85 1946 0.65
56 ' 8.39 10.15 5 1 1.76 2045 1.35
Mean 7.79 5.18 1.77 2105.10 0.69
72


References:
1. Methodology for Optimizing Signal Timing: MOST Volume 3, Passer
11-90 Users Guide. U.S.D.O.T., Federal Highway Administration,
Washington, D.C., 1991
2. N. Stamatiadis, K. R. Agent, and A. Bizakis. Guidelines for Left-Turn
Phasing Treatment. In Transportation Research Record 1605, TRB,
National Research Council, Washington, D.C., 1997
3. J. Upchurch. Comparison of Left-Turn Accident Rates for Different
Types of Left-Turn Phasing. In Transportation Research Record
1324, TRB, National Research Council, Washington, D.C., 1991
4. J. Upchurch and C. H. Wright. Before and After Comparison of
Leading Exclusive and Permissive/Exclusive Lagging Left Turn
Phasing. In Transportation Research Record 1368, TRB, National
Research Council, Washington, D.C., 1992
5. Special Report 209: Highway Capacity Manual. TRB, National
Research Council, Washington D. C., 1994
6. A. J. Hayter. Probability and Statistics for Engineers and Scientists.
PWS Publishing Co. Boston, MA. 1996.
73