HomeMy WebLinkAboutItem 5.3 Dougherty Road Traffic Study (2) AGENDA STATEMENT
CITY COUNCIL MEETING DATE: July 23, 1984
SUBJECT: Public Hearing Dougherty Road
Traffic Study and Plan Line
EXHIBITS ATTACHED: 1) Summary of Recommended Improvements
2 ) Traffic Report
3 ) Plan of the proposed road alignment
to be displayed at the hearing
RECOMMENDATION: 1 ) Hear staff presentation
2 ) Open public hearing
3 ) Take public testimony
4 ) Close public hearing
5 ) Accept traffic study and direct
staff to include recommended traffic
improvements (or as modified) into
the 5 year Capital Improvement
Program for future consideration.
FINANCIAL STATEMENT: Estimates have not been completed at
this time, but will be included in the
next review of the 5 year Capital
Improvement Program
DESCRIPTION: Public hearing to review and accept a
traffic study and a preliminary plan line on Dougherty Road
between Dublin Boulevard and the northern City limits . The
purpose of the study was to identify needed safety and
capacity improvements . The plan line will reflect these
improvements graphically and will establish a basis for
identifying future capital improvement projects .
The right of way is proposed at 110 feet with a four lane
divided roadway expandable to 6 lanes by removing the
outside parking/bike lanes . The right of way is envisioned
to flair out at Amador Valley Boulevard intersection for a
double left turn lane and at Dublin Boulevard for additional
turn lanes .
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ITEM NO. J - COPIES TO:
DOUGHERTY ROAD TRAFFIC STUDY
SUMMARY OF RECOMMENDED IMPROVEMENTS
1 . Provide four lanes with the ability to widen to six
lanes with landscaped medians .
2 . Widen at Dublin Boulevard for additional turning lanes .
3 . Provide an intersection for a new street parallel to the
railroad right of way, heading southeast toward the
future extension of Dublin' Boulevard.
4 . Provide a dual left turn from Dougherty Road onto Amador
Valley Boulevard.
5 . Straighten out curves north of Amador Valley Boulevard.
6 . Ultimate medians to be installed between Sierra Lane and
the Southern Pacific Railroad with selected median
breaks . Intrim median improvements would include two
way striped turning lanes because of the many driveways .
A TT:/ - /
DOUGHERTY ROAD
TRAFFIC STUDY
IN THE
CITY OF DUBLIN
By
TJKM Transportation Consultants
4637 Chabot Drive, Suite 214
Pleasanton, CA 94596
MAY 1984
15706
TABLE OF CONTENTS
PAGE
IINTRODUCTION ..... ... .. ..... . ........ ..... ................... 1
IIEXISTING CONDITIONS .... ..................... ................ 3
Existing Roadway...... ............ ......................... 3
Daily Traffic Volumes................0.....0....0.0........ 3
Traffic Accidents. ......................................... 4
Peak Hour Traffic.......... ........ ........................ 5
IIIFUTURE CONDITIONS .......... ................................. 7
Land Use....................
Traffic Projections................................ 8
Future Intersection Levels of Service..................... ......... 8
IVRECOMMENDATIONS...................... ............ ....0....... 10
Street Width.................................. ............. 10
Interstate 580 Interchange.. 10
Intersection Configuration.. 11
Access.............. ...... .. ............................... 11
Signalization... ..... . . .. .... ............. ............ .. ... 12
Lighting........... .. .... ........ .. ...... . ................. 13
Improvement Projects and Priorities......... 13
APPENDIX Description of Intersection Capacity Analysis
TABLES FOLLOWING PAGE
I Dougherty Road Plan Line Study Capacity Analysis............. 6
IILand Use and Trip Generation....... ..... .. .. ................. 7
III Left and Right Turn Lane Storage Lengths.... ..... ........... . 11
FIGURES
1 Possible Future Land Use and Traffic Zones........ ........... 7
2 I-580 Interchange Improvement Plans.. ..... ........... ........ 10
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- DU-8L-1-1—BOULEVARD TRAFFIC STUDY
V �
I INTRODUCTION
The City Council of the City of Dublin has requested that a
comprehensive traffic study be performed of Dougherty Road so that short
term and long term transportation and land use issues could be
addressed. This report constitutes a summary of the study.
The study had several purposes:
1. To define the future street and lane requirements for Dougherty Road
within the Dublin City limits. The specific area is between the
Interstate 580 (I-58U) Freeway and the City's northern limits , which
is also the Alameda County/Contra Costa County/City of San Ramon
boundary.
2. To resolve traffic access issues along Dougherty Road.
3. To determine signalization requirements at intersections along
Dougherty Road.
4. To review and determine striping needs on a short term basis.
5. To review and recommend lighting needs along Dougherty Road.
6. To define and recommend short term and long term improvement
projects for Dougherty Road.
The methodology of the study consisted of determining the existing
traffic conditions along Dougherty Road primarily in the form of peak
hour counts, 24 hour counts and existing traffic capacities. The future
land use possible for the study area was analyzed to determine
generalized traffic patterns in the future. Capacity analyses of the
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future traffic were conducted and a recommended street system was
determined.
All other issues related to the purpose of the study described above are
also addressed in this report. The study was a cooperative effort with
.participation as follows : Land use estimation by the City of Dublin
Planning Director, the Contra Costa County Planning Department and
Blayney-Dyett Urban and Regional Planners ; traffic projections and
recommendations and report preparation by TJKIN Transportation
Consultants ; and preparation of drawings depicting future street
requirements by Santina and Thompson.
i
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II EXISTING CONDITIONS
Existing Roadway
As depicted on the aerial photographs which accompany this report ,
Dougherty Road north of the Southern Pacific Railroad (SPRR) tracks is a
two-lane roadway. Between the SPRR tracks and Sierra Lane, it is a
two-lane divided roadway with a 730-foot long center two-way left-turn
lane near Sierra Lane.
Between Sierra Lane and the K-Mart driveway, it is a two-lane roadway
with raised median. From the K-Mart driveway to Dublin Boulevard, it
widens into a four-lane divided facility. South of Dublin Boulevard, it
has two southbound lanes , one of which leads directly onto the I-58U
westbound on-ramp. The existing overpass over I-580 is a two-lane
structure. North of the overpass, the roadway widens from one to three
lanes in the northbound direction before reaching Dublin Boulevard.
A four-phase traffic signal exists at the intersection of Dublin
Boulevard and Dougherty Road. This traffic signal installation is under
the jurisdiction of the City of Dublin. All other intersections are
regulated by STOP signs protecting Dougherty Road traffic.
Daily Traffic Volumes
Daily traffic volumes are a measure of the use of the roadway and are
helpful in determining lane requirements . At the present time, the
daily volume on Dougherty Road north of Amador Valley Boulevard is
approximately 3,200 vehicles per day (vpd ) . Between Amador Valley
Boulevard and Sierra Lane , there are between 7 ,700 and 9,200 vpd.
Between Sierra Lane and Dublin Boulevard, there are approximately 13,000
vpd. South of Dublin Boulevard, there are approximately 30,000 vpd.
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In a generalized sense, maximum traffic capacities for various types of
roadways are as follows :
Two lanes . ............ 15,000 vehicles per day
Four lanes divided .... 30,000 vehicles per day
Six lanes divided . ... 40,000 vehicles per day
Based on these generalized capacity figures, it can be seen that present
traffic volumes along Dougherty Road are less than the maximum
capacities.
Traffic Accidents
A review of reported traffic accidents is a means of determining
generalized existing safety problems in a street network. Traffic
accidents frequently occur due to driver error and inattention. In
addition, road and vehicle defects are sometimes factors in the traffic
accident involvement. The 1981 , 1982 and 1983 summaries of reported
traffic accidents for Dougherty Road were reviewed as a part of this
study.
In 1981 , 6 vehicle accidents occurred between the City ' s northern
boundary and Amador Valley Boulevard, including 5 injury accidents ; 8
vehicle accidents occurred between Amador Valley Boulevard and Sierra
Lane, including 2 injury accidents ; and 5 vehicle accidents occurred
south of Dublin Boulevard.
In 1982, 5 vehicle accidents occurred between Amador Valley Boulevard
and Sierra Lane, including one injury accident; 4 accidents occurred on
Dougherty Road near the Dublin Boulevard intersection , including one
motorcycle injury accident; and no accidents occurred north of Amador
Valley Boulevard within the city limits.
In 1983, 2 vehicle accidents occurred between Amador Valley Boulevard
and Sierra Lane; 8 accidents occurred on Dougherty Road near the Dublin
Boulevard intersection, including 2 injury accidents.
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These data indicate that there is one accident concentration location on
Dougherty Road - the Dublin Boulevard intersection. The typical traffic
accident at these accident concentration locations was classified as a
rearend type. There were a few right-angle, hit-object and other types
of accidents as well . A large percentage of the accidents that occurred
on Dougherty Road had a primary collision factor of "unsafe speed".
Access control measures recommended in this report should reduce
accident rates at mid-block locations. Recommended improvements for the
Dublin Boulevard intersection could provide a safer operational
environment for traffic. Also , the modification and signalization at
the I-580 interchange , as recommended in the report, could reduce the
number of accidents occurring near the interchange.
Peak Hour Traffic
An investigation was made of both a.m. and p.m. peak hour traffic flow
at all intersections along Dougherty Road. The purpose of such counts
is to determine lane-by-lane traffic flow, relative traffic flow among
various approaches to an intersection, and overall traffic levels within
an intersection . In most urban areas , including Dougherty Road ,
intersections are the points of most limited traffic capacity.
Locations between intersections usually do not suffer congestion-related
problems. Peak hour movements at the intersections are also useful in
analyzing the operation of traffic signals.
Following the completion of the existing traffic counts during the peak
hours , the traffic capacity of each intersection was determined. The
method of intersection capacity analysis utilized in this study is the
critical lane method in which the volume and capacity of each critical
signal phase at an intersection are evaluated to produce an overall
intersection volume to capacity ratio. Each ratio has a comparable
"level of service" rating which provides a single letter evaluation of
the traffic at the intersection during the evaluated hour. The ratings
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vary from Level of Service A (with very good traffic conditions) to
Level of Service F (with very poor traffic conditions ) . A complete
description of the capacity analysis is shown in the Appendix.
The first 2 columns in Table I on the following page list the existing
volume-to-capacity ratios at four major intersections along Dougherty
Road. All intersections were evaluated as though they were currently
regulated by traffic signals . Even though this does not exactly
simulate existing field conditions , it provides a relative analysis of
all intersections for comparative purposes. Not surprisingly, the
intersection of Dublin Boulevard/Dougherty Road has the poorest
operation during the p.m. period . During the p.m. peak hour, the
intersection is operating at Level of Service F. The I-580 westbound
ramps intersection also operates at poor conditions in the evening peak
hour during which time Level of Service E operation exists. Level of
Service B exists during the a.m. and p.m. peak hours at the Sierra Lane
intersection . The Amador Valley Boulevard intersection operates at
Levels of Service A throughout the day.
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TABLE I
CITY OF DUBLIN
DUBLIN BOULEVARD PLAN LINE STUDY
PEAK HOUR CAPACITY ANALYSIS
Future
Existing Future Mitigated
AM PM PM PM
V/C LOS V/C LOS V/C LOS V/C LOS
Dougherty Road at
Amador Valley Boulevard 0.37 A 0.41 A 0.68 B 0.41 A
Sierra Lane 0.63 B 0.68 B 0.87 D 0.66 B
Dublin Boulevard 0.62 B 1.11 F 1.23 F* 0.92 E
I-580 WB Ramps 0.72 C 1.00 E 1.24 F / 0.74 C
See the Appendix for Level of Service descriptions.
* Interim intersection modifications scheduled for 1984
considered.
V/C = Volume to Capacity Ratio
LOS = Level of Service
III FUTURE CONDITIONS
Land Use
In order to determine future traffic volumes on Dougherty Road and its
intersections , it was necessary to estimate the possible future land use
development in those currently vacant areas directly and indirectly
affecting traffic on Dougherty Road. Table II on the following page
lists the possible land use development in the study area. N total of
49 such uses are identified including several proposed residential
subdivisions. In some cases a variety of land use possibilities exists
for a given area based on allowances within existing general plan and
zoning designations and the practicalities of future development . For
the purposes of this study, the higher traffic generation use was
evaluated. However , in very few cases was the higher traffic producing
use significantly higher than the alternate land use.
It should be pointed out that under this method of analysis , the
complete accuracy of the prediction for a possible land use is not
essential . Since some of the traffic evaluated is already on the street
and a number of future land use developments are considered , the
relative impact of any one development is not substantial . Note that
the first portion of Table II gives specific details on the possible
development areas , and the final portion gives trip generation
information of those developments.
Figure 1 portrays the location of each of the developments and the
residential subdivisions considered in this analysis. In addition ,
Figure 1 shows the 12 traffic zones comprising the study area. The
traffic zones have been established for the ease of distributing and
assigning future traffic to the planned street network.
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TAB LE I I
LAND USE AND TRIP GENERATION
TRIP GENERATION ANALYSIS FOR THE DUBLIN PLAN LINE STUDY 3/1/34
TJKM
+----------LAND USE DATA----------+ +--DAILY VTE PER---+ +-____ +-P.-M. PEAK HOUR--+
ADT------+20NE ID No. Description 1000 sf Units Units Stalls 1000 sf Unit Stall Prelim DT %Disc `IADT %ADT Total In Out SF MF - Park
'---------------------------------------
------------11---°--
1 1-A Tract 4668 ---------------- __�___-__
1-B Tract 4802 84 935 935 10 94 62 32
I-C Tract 4749 78 11 924 924 10 92 61 31
1-D Tract 4959 40 11 550 458 10 86 57 29
1-E Tract 4011 48 11 440 440 10 44 29 15
1-F Nielsen 261 11 528 528 10 53 35 18
1-G Townhouses 129 11 c^871 2871 10 287 189 98
1-H Barratt 112 9 10dB 1061 9 93 61 322
1-I Multi-Family 378 9 3402 3402 8 272 BI °3 27
1-J Multi-Family 56 9 504 504 8 40 120 14
1-K Single Family 42 11 462 462_ 10 46 30 16
13093 1186 7u4 6404
2-
2 2-A Mufti-Family 133 9 1197 1197 B 96 63 33
B Office 66.0
2 12 792 10 713 20 143 29 114
2-D-C Office 12.0 12 144 10 130 20 26 5 21
Office 50.0 12 600 10 540 20 108 22 86
2-E Apartments 288 B 2304 2304 8 184 122 63
2-F Commercial 120.0 Be 9600 35 6240 15 936 468 468
11123 1493 708 6784
3 3-A Commercial 65.0 50 3250 35 2113 15 317 158 158
3-B Commercial 175.0
3-C BART Station 50 8750 35 5688 15 853 427 427
3-D Motel 12250 4 5000 15 4250 15 639 319 319
80 10 800 800 15 120 60 60
=7;===
2850 1928 964 6964
4 4-A Office 37.0
4-B Office 15.0 12 444 10 400 20 80 16 '64 4-C Commercial 26.0 12 180 10 162 20 32 6 26♦-D Commercial 24.5 50 1300 35 845 15 127 63 63
50 1225 35 796 IS 119 60 60
2203 359 6146 6213
5 No New Development
6 6-A Multi-Family 121 9 1089 1089 8 87 57 30
6-8 Multi-Family 53 9 477 477 8 38 25 13
6-C Single Family 26 11 286 286 10 29 19 10
1852 154 102 6=52
7 No New Development
B B-A Office 20.0 12 240 10 216 20 43 9 35
Lt. Industrial 20.0
8-B Office 120 10 108 20 22 4 •7
23.4 12 281 10 253 20 51
Lt. Industrial 12.6 10 4 0 6 76 10 68 20 14 3 11
B-C Office 68.0 12 816 10 734 20 147 29 118
Lt. Industrial 36.5 6 219 10 197 20 39 8 32
9 9-A Motel 150 6 1576 315 63 6252
9-B Office 40.0 10 1500 1500 15 225 113 113
Research 16.3 12 460 10 432 20 86 17 69
9-C Office 169.0 12 2028 10 1825 20 365 73 292
10 10-A Lt. Mfg 157.0 6 3845 690 205 484
Office 17.0 6 942 10 848 15 127 19 108
10-B Lt. Industrial 78.3 12 204 10 184 29
20 37 7
Office 8.7 12 470 10 423 20 85 17 68
10-C Lt. Industrial 39.2 6 104 10 94 20 19 4 15
Office 4.4 235 10 211 20 42 B 34
10-D Lt. Industrial 107.6 1 52 10 47 20 9 2 B
6
Office 57.9 645 10 626 20 116 23 93
10-E Lt. Industrial 74.5 12 695 10 626 20 125 25 100
Office 8.3 6 447 10 402 20 80 16 64
10-F Lt. Industrial 82.4 12 94 10 89 20 18 4 10 20 89 Office 9.2 12 110 10= -499 20 _ 20 I4 16
4048 767 147 6620
11 I1-A Single Family 150
Apartments 552 11 8 4416 4456 10 165 X09 56
I1-9 Multi-Family 1106 9 9954 9954 8 353 33 120
I1-C Townnouses 309 8 796 526 271
11-D Multi-Family 53 9 2781 2781 B 222 147
9 477 477 76
I1-E Multi-Family 42 9 378 _ 378 B 30 20 10
19656 1605 1060 6546
12 12-A Condos
12-B Townhouses 227 9 2250 2250 8 180 119 67
20
12-C Duplexes 9 243 243 B 14 13 7
9 450 180 8 14 10
12-D Single Family 132 11 1452 = 1452 10 145 96 49 9
4125 359 6237 122
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OTraffic Zone
- Number And Boundary
IA = Possible Land Use Development(See Text)
DOUGHERTY ROAD TRAFFIC STUDY
POSSIBLE FUTURE LAND USE F I G U R E
AND TRAFFIC ZONES I
14o�—" Z49
Traffic Projections
Future traffic volumes were determined by adding existing traffic to the
traffic resulting from the possible developments described in the
previous section. Various traffic generation rates were used according
to the specific land use considered. The following trip generations
rates were used in this study:
Daily Traffic Generation Rate
Land Use Trips per day
Residential
Single family 11 per unit
Town Homes and Condominiums 9 per unit
Apartments 8 per unit
Offices 12 per 1,000 sq. ft.
Commercial
Community Commercial 80 per 1,000 sq. ft.
Regional Commercial 50 per 1,000 sq. ft.
Motel 10 per unit
BART station 4 per parking stall
Light Industrial 6 per 1,000 sq. ft.
For the purposes of this evaluation , land use Area 3C depicted in
Figure 1 was assumed to be a future BART station. Although the station
location has not been formally adopted, it is a logical site currently
being considered in the BART extension studies, and it is included in
this study in order to determine worst case analyses of traffic
conditions in Dublin.
Future Intersection Levels of Service
Table I, following page 6, indicates the resulting traffic conditions at
the 4 major intersections when the new traffic is added to existing
traffic along Dougherty Road. Two different future conditions are
analyzed. In the first case , the future traffic is analyzed on the
existing street network except that a new I-680 interchange with
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• I �n°� 2�
northbound on-ramp and off-ramp at Village Parkway and southbound
on-ramp and off-ramp at Amador Plaza Road was assumed. In the second
case described in the Table as "future mitigated" , the recommended
improvements for the street network with the assumed new interchange is
tested and evaluated.
Not surprisingly, when future traffic is added to the existing street
network, three of the four analyzed intersections would operate at or
near undesirable traffic conditions during at least the evening peak
hour period. The conclusion is that some sections of Dougherty Road
need to have additional traffic capacity. It should be noted that
proposed projects in Contra Costa County outside of the study area would
probably generate more than 20,000 additional vehicle trips per day,
which if considered will necessitate ,the expansion to 6 lanes on
Dougherty Road by removing the planned parking lanes in the future.
Specific recommendations for improved capacity are described in the next
section of the report.
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IV RECOMMENDATIONS
Street Width
The plans accompanying this report indicate recommended lane patterns
for Dougherty Road in the study area. The recommended lane pattern is
as follows: From the northern City limits to Sierra Lane, a four-lane
divided facility with a 14-foot wide parking/bike lane on each side is
recommended. Near the City limits , a modified horizontal alignment with
a smaller degree of curvature should be provided. Between Sierra Lane
and Dublin Boulevard , 2 northbound lanes and 3 southbound lanes are
recommended. South of Dublin Boulevard to the I-580 westbound ramps , 3
northbound lanes and 3 southbound lanes are recommended. However, one
of the southbound lanes should be leading exclusively onto the westbound
on-ramp. Recommendations regarding the I-580 interchange are described
in the following section.
Sidewalks should be provided throughout on both sides of Dougherty Road.
Interstate 580 Interchange
At the present time, the interchange has loop on-ramps in the northeast
and southwest quadrants and has unsignalized left-turn off-ramp
approaches for both westbound and eastbound traffic on I-580. The
existing overpass is only two lanes in width.
The recommended ultimate configuration shown in Figure 2 consists of an
additional structure over I-580 accommodating three traffic lanes.
Three northbound lanes and two southbound lanes should be provided on
the overpass in the future . The combining of the left-turn and
right-turn off-ramp approaches is also recommended. All left-turn and
right-turn vehicles off each off-ramp should be controlled by a traffic
signal installation.
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(INTERIM PLAN) I ii i�� I (ULTIMATE PLAN)
DOUGHERTY ROAD TRAFFIC STUDY
I- 580 INTERCHANGE F I G U R E
IMPROVEMENT PLANS w 2
TRANSPORTATION CONSULTANTS
Intersection Configuration
Following the analysis of specific traffic movements during peak hours
at each of the study area intersections , it is possible to recommend
specific numbers of turning lanes as well as the length of the turn
lanes.
Single northbound left-turn lanes should be provided at Ventura Drive,
South Mariposa Drive, Monterey Drive and Sierra Lane. Single southbound
left-turn lanes should be provided at the Camp Parks entrance and Sierra
Lane.
At Amador Valley boulevard , a northbound dual left-turn lane is
recommended.
At Dublin Boulevard, restriping the northbound approach to contain a
dual left-turn lane , a through lane , and a through plus right-turn
combination lane is recommended. The southbound approach should be
restriped to contain a left-turn lane , a right-turn lane , and three
through lanes .' The eastbound approach on Dublin Boulevard should be
restriped to contain two right-turn lanes , a left-turn lane , and a
through lane. The westbound approach should be widened to provide a
dual left-turn lane.
Table III on the following page describes the recommended length of
right-turn lanes and left-turn lanes at major intersections along
Dougherty Road. These numbers nave been derived from the estimated
projected future turning movements at each intersection.
Access
At the present time, there are many driveway access points on both sides
of Dougherty Road. At some locations , left-turn movements in and out of
driveways are a barrier to safety and capacity. Therefore, left-turn
movements should be prohibited at certain access points.
-11-
TABLE III
RECOMMENDED MAXIMUM
LEFT TURN AND RIGHT 'TURN LANE
STORAGE LENGTHS (FEET)
Southbound Northbound
L J`f R 17 1 R
(Feet) (Feet) (Feet) (Feet)
Dougherty Road at
Aaador Valley Boulevard - - 26U(2) -
Sierra Lane 100 - 200
Dublin Boulevard 250 200 300(2) -
I-580 WB Ramps - -
R/T = Right turn lane
L/T = Left turn lane
(2) = 2 lanes , each of recommended length
20,04", z(0
The closing of the median opening between Dublin Boulevard and Sierra
Lane is recommended due to the need to lengthen the southbound left-turn
lane at the Dublin Boulevard intersection.
The two-way left-turn lane north of Sierra Lane should be replaced by
raised median , and only one median opening is recommended for that
segment of Dougherty Road. It is also recommended that .no median
opening be provided at North Mariposa Drive since access could be
obtained by using the South Mariposa Drive intersection.
For long term planning, it is recommended that a new entrance for Camp
Parks be provided on Dougherty Road opposite Monterey Drive, and the
existing entrance be closed off.
A new four-lane divided roadway connecting Dougherty Road and the Dublin
Boulevard extension has been proposed to be located generally parallel
to the Southern Pacific railroad tracks . This proposed roadway would
provide a more direct travel path for vehicles traveling from areas
along Dougherty Road north of the railroad tracks to areas along the
planned Dublin Boulevard extension or vice versa ; and hence , could
divert some traffic away from the intersection of Dublin Boulevard and
Dougherty Road. This proposed roadway would form a "T" intersection at
Dougherty Road south of the existing Camp Parks entrance.
Signalization
In addition to the existing traffic signal installation at the Dublin
Boulevard intersection, future traffic signals will be needed at , in
order of priority, I-580 westbound ramps (now being designed) , Sierra
Lane, and Amador Valley Boulevard . The detailed signal design
requirements at each of the future signals will need to be determined at
the time of the signal installation. Also, it may not be appropriate to
install traffic signals until street improvements in the immediate
vicinity are made.
-12-
Z o-F
In addition to the new signals , it will become very important to
coordinate signals along Dougherty Road . This will be especially
important following the installation of signals at the I-580
interchange. At that time, the coordination of Dougherty Road , I-580
interchange and Hopyard Road signals will be very desirable. In order
to accomplish this , an interconnect system should be considered. This
will consist of cable within the street right away connecting each of
the signals along the street. In order to provide overall coordination ,
connection with the City of Pleasanton traffic signal master should be
accomplished. Both the City of Pleasanton and the City of Dublin have
previously discussed such a concept. The computer master is currently
installed at' the Pleasanton City Hall and has been operating since June
1983. It would be possible to coordinate the signals along Dougherty
Road following a completion of detailed arrangements and agreements
between the two cities . As intersections are brought into system
operation , it will be necessary to revise and upgrade some of the
existing signal controllers.
Lighting
The existing lighting system on Dougherty Road is inadequate except at
the Dublin Boulevard intersection. Additional street lights should be
installed at a spacing of approximately 300 feet along the existing and
proposed raised medians . Lighting at all intersections should be
emphasized.
Improvement Projects and Priorities
Extensive funding requirements are necessary to improve Dougherty Road
to its ultimate recommended width . It is logical to stage the
improvements of Dougherty Road so as to resolve the highest priority
problems first . Areas felt to require attention on a short term basis
include the improvement of the Dublin Boulevard/Dougherty Road
-13-
2z
intersection, and the restriping, modification, and signalization of the
I-580 interchange (now under design ) . Longer term needs include the
widening of Dougherty Road to accommodate four through lanes and two
parking/bike lane , signalization and median modification near Sierra
Lane, and widening of the 1-580 overpass.
An interim improvement plan , which does not require the construction of
an additional bridge structure, is planned for the I-580 interchange.
(See Figure 2. ) Signalization , ramp modification , and restriping are
included in the interim plan. This interim plan is presently in the
design stage and is scheduled to be completed in the summer of 1984.
The most urgent needs at the Dougherty Road intersection consist of
acquiring provisions for an additional eastbound right-turn lane, a
northbound dual left-turn lane, and two northbound through lanes. These
improvements have been included in an interim plan scheduled for 1984.
These projects should be prioritized with other needed improvements in
the City of Dublin and incorporated into the updated five year Capital
Improvement Program.
-14-
APPENDIX
2 qof z�
APPENDIX
DESCRIPTION OF INTERSECTION CAPACITY ANALYSIS
TJKM utilizes a method of intersection capacity analysis known variously
as the critical lane method , critical movement summation or by other
descriptions. A variation (and derivation) of the TJKM method, known as
the critical movement analysis , is described in Interim Materials on
Highway Capacity, Transportation Research Circular 212, January 1980,
published by the Transportation Research Board of the National Academy
Of Sciences. The TJKM method is similar to the Planning Applications
method of Signalized Intersection Analysis described in Circular 212.
The method sums the volume-to-capacity ratio of each governing (or
critical ) signal phase at an intersection to produce an overall
intersection volume-to-capacity ratio. When the ratio of volume and
capacity reaches unity, the intersection is "at capacity" and is
described as operating at Level of Service E and approaching Level of
Service F conditions. See the table "Levels of Service and Volume to
Capacity Ratios " for the relationship between the level of service
rating and volume-to-capacity ratio.
A sample calculation is shown on the accompanying computer printout
"TJK11 Intersection Capacity Analysis . " This example describes a
hypothetical intersection of A Street and B Street , which is regulated
by three phase traffic signals . The first phase is for southbound
traffic only and contains three lanes . Right turn movements in the
right lane (189 vehicles) have a smaller per lane volume than in the two
remaining lanes (226 vehicles) . Therefore , the length of the signal
phase is governed by the traffic in the two left lanes. The capacity of
Phase 1 is 2,600 vehicles per hour of green , the volume is 452 vehicles
and the resulting volume-to-capacity ratio is 0. 174. Phase 2, the
northbound movements , has 2 lanes and a volume-to-capacity ratio of
0.168. For Phase 3, the westbound through plus right traffic cannot
proceed through the intersection at the same time as the eastbound left
turn movement , even through they are on the same signal phase.
Practically, the left turners and opposing through traffic alternate as
gaps in traffic allow. The total Phase 3 capacity requirement is the
sum of the westbound through and right combined , 0.205 , and the
eastbound left, 0.08. The four critical movements are summed, along
with an allowance for yellow time (assumed to be lost time for vehicle
movement) to obtain the overall intersection volume-to-capacity rating.
In the example , the intersection rating of 0.73 equates to a Level of
Service C designation.
The advantages of this type of capacity calculation is its direct
relationship to actual intersection operations and the ease with which
changes in volume or capacity (or both) can be analyzed. In addition ,
the level of accuracy of this method is comparable to that of the
traffic projection process used to determine future or project traffic
volumes.
250 2_e00
LEVELS OF SERVICE AND VOLUME-TO-CAPAC ITY RATIOS
LEVEL
OF
SERVICE DESCRIPTION V/C RATIO
A Free flow (relatively) . If signalized , conditions 0.00 - 0.60
are such that no approach phase is fully utilized
by traffic and no vehicle waits through more than
one red indication. Very slight or no delay.
B Stable flow. If signalized , an occasional approach 0.61 - 0.70
phase is fully utilized ; vehicle platoons are
formed. This level is suitable operation for rural
design purposes. Slight delay.
C Stable flow or operation . If signalized , drivers 0.71 - 0.80
occasionally may have to wait through more than one
red indication . This level is suitable operation
for urban design purposes. Acceptable delay.
D Approaching unstable flow or operation ; queues 0.81 - 0.90
develop , but are quickly cleared. Tolerable delay.
E Unstable flow or operation ; the intersection has 0.91 - 1.00
reached ultimate capacity ; this condition is not
uncommon in peak hours. Congestion and intolerable
delay.
F Forced flow or operation . Intersection operates 1.00+
below capacity. Jammed.
Source : Highway Capacity Manual , HRB Special Report 87
i
TJKM 1NIERSECIION CAPACITY ANALYSIS MOVEMENT VOL. CAPACITY ADJ. VOL. V/C
--------------------------------------------------
JUHISDICfIUN: IJ):M SAMPLE COUNr NUMBER: 1 NB HIGHr (R) I 10 1 1500 I 10 1 .007
INTERSECTION: A STREET L D STREET COUNr DAME: 3/14/83 rHRU (T) 1 484 1 3000 1 484 1 .161
CONDIIION: P.M. PEAK HOUR--EXISTING TIME OF COUNT: 4:00-6:00PM LEFT (L) I 10 1 1500 I 10. 1 .007
DATExANALYZEDS 6/6/83 PEAK HOURS 4:30-5:30PM T + R I 494 I 3000 I 494 1 ,IE.5
T + I 1 494 1 3000 1 4'74 1 .165
RIGHT THRU LEFT T + R + L 1 504 I 3000 1 504 I .IE•8
189 225 227 ^ _ _ _ _ _ _ _ _
I I I I
^ SG RIGHT (R) 1 189 1 137b 1 79 * 1 .057
1 1 1 ^ NORTH THRU (T) 1 225 1 1500 1 225 ( .15
I <--- v ---> I LEFT (L) 1 227 1 2600 1 227 1 .087
LEFT 110 --- 1 1 1.1 2.1 1.1 --- 2 RIGHT T + R , 1 0 1 0 I 0 1 0
STREET NAMES T + L 1 452 1 2600 1 452 1 .174
THRU 623 ---> 2 (NO. OF LANES) 2.1<--- 644 THRU A STREET T + R + L I 0 1 0 I 0 1 0
--------------------------------------------------
RIGHT 15 --- 1 1.1 2.2 1.1 1 --- 11 LEFT SPLIT PIIASE? EB RIGHT (R) 1 15 1 1375 I 0 ■ 1 0
I <--- ^ ---> 1 0 THHU (() 1 623 1 3300 1 623 I .189
v I I I v (0-NO.1=YES) LEFT (L) I 110 1 1375 I 110 I .08
1 I I T + R 1 0 1 0 I 0 1 0
10 484 10 T + L I 0 1 0 I 0 1 0
LEFT THRU R1 Gil T T + R + L 1 0 1 0 I 0 1 0
STREET NAMES 8 STREET SPLIT PHASE? 1 WB RIGHT (R) 1 2 1 1500 1 2 1 .001
THRU (T) 1 644 1 3150 I 644 1 .204
I CRITICAL ( CAPACITY OF I V/C OF LEFT (L) 1 11 1 1375 I 11 I .008
MOVEMENT 1 VOLUME 1 CR1rICAL MOVEMENT' I CRITICAL MOVEMENT T + R I 646 1 3150 1 646 I .205
---------------7--------------------------------------------------
---
ND RIGHT (H) T + L 1 0 1 0 I 0 1 0
1 0 1 0 I 0 T + R + L I 0 I 0 I 0 1 0
1HHU (1') I 0 I 0 1 0 --------------------------------------------------
LEFT (L) I• 0 1 0 I 0
1 + R I 0 I 0 1 0 --THRU-- --TURN-- RELATIONSHIP OF
T + L I 0 1 0 I 0
N0. OF N0. OF V/C LOS
- -T-+-R-+-L-I_ - - -504 I 3000 I .14.8 LANES CAP. LANES CAP. .001 1
- - - - - - - - - - - - - - - - - - - - - - - - - - - 0 0 0 0 .605 2
SB RIGHT' (R) 1 0 I 0 1 0 .9
THRU ('r) 1 0 1 0 I 0 1 1650 1 1375 .805 4
LEFT (L) 1 0 1 0 1 0 1.1 1500 1.1 1500 .905 5
T + R 1 0 I 0 1 0 1.9 0 1.9 0 1.01 6
T + L 1 : 452 I 2600 I .174 2 3300 2 2475
T + R + L I ' 0 1 0 1 0 2.1 3150 2.1 2600 YELLOW TIME
---------------------------------------------------------------------------- 2.2 3000 2.9 0 ADJUSTMENTS
EB RIGHT (R) 1 0 1 0 i 0 2.9 0 3 3575 .001 .1
THRU (T) 1 0 1 0 1 0 3 4950 3.1 3700 .725 .09
LEFT (L) I 110 I 1375 1 .08 3.1 4800 9179 0 .745 .08
T + R I 0 1 0 I 0 3.2 4650 .765 .07
T + L 1 0 I. 0 1 0 3.9 0 .785 .06
- -T-+-R-+-L-I- - - - 0 1 0 1 0 4 6600 .805 .05
- - - - - - - - - - - - - - -
- - - - - 4.1 6450 .825 .04
- - - - -
WB RIGHT (R) 1 0 I 0 1 0 4.2 6300 .845 .03
THRU (T) 1 0 I 0 1 0 4.'? 0 .865 .02
LEFT (L) 1 0 I 0 1 0 5 8250 .885 .01 N
T + R 1 646 I 3150 I .205
5.1 8100 .8'�S 0
T + L I 0 1 0 1 0 5.2 7950 ;999 0
T + R + L I 0 1 0 I 0 999 0 d
aaa=x=zaa=ae=cc=amac===mss=ce=cs==eae=ass=a=ssx==sae=aa=asa===mcx=a=cc=cs=cca * n VOLUME WAS ADJUSTED FOR
VOLUME-'10-CAPACI7Y RATIO FOR THC INTERSECTIONS I ,63 RIGHT TURNS ON RED.
ADJUSIMENT FOR LUST YELLOW TIME: I .10 6
-------------------------------------
---------------------------------------
***� TOTAL VOLUME-TO-CAPACITY RATIOS I .73
1 TJKM / dnp83
3*** INTERSECTION LEVEL OF SERVICES I C