HomeMy WebLinkAbout4.4 Reducing the Speed Limit on Segments of Arnold Road and Tassajara RoadPage 2 of 4
Procedure for Establishing Speed Limit
The E&TS (Attachment 2) is conducted in compliance with CVC Sections 627, 22358.5 and
21400(b) and California Manual on Uniform Traffic Control Devices (CA MUTCD) Section 2B.13.
The E&TS determines the operative criterion called the “85th percentile” or “critical” speed. The
“85th percentile” speed is considered the target speed at or below which 85% of drivers are
travelling in free-flowing conditions. Posted speed limits are to be set at the nearest five-miles-
per-hour (5 mph) increment to the critical speed. The E&TS also includes an analysis of the
roadway to determine whether there are any offsetting factors, such as residential density,
pedestrian and bicycle features, intersecting driveways, accident history, and location of schools,
which would cause the recommended speed limit to be further reduced by five miles per hour.
Engineering and Traffic Survey (E&TS) Findings
The E&TS of the road segments on Arnold Road and Tassajara Road recommends the following
reductions in the current posted speed limit.
a. Arnold Road between Dublin Boulevard and Gleason Drive from 40 mph to 35 mph.
b. Tassajara Road between Dublin Boulevard and Gleason Drive from 45 mph to 40 mph.
c. Tassajara Road between Fallon Road and the northern City limit from 45 mph to 40 mph.
These recommendations were based on the 85th percentile speeds, the recent changes in roadway
characteristics, and adjacent land uses that generate additional pedestrian and bicycle activities.
Attachment 3 shows the existing and proposed changes to the subject segments. The
recommendations are detailed below.
Arnold Road between Dublin Boulevard and Gleason Drive
The subject segment of Arnold Road is classified as a minor arterial in the City of Dublin’s
Roadway Functional Classification System. Roadway characteristic changes include increased
bicycle and pedestrian usage due to the addition of Class II bike lanes, new crosswalks, median
improvements, traffic signal improvements and modifications, and residential access
improvements along Arnold Road with its intersections with Central Parkway and Horizon
Parkway. Land use changes include construction of new multi-family residential units (Boulevard
Development) on the west side of Arnold Road and construction of the new Zeiss Meditech office
building on the east of the roadway. Pedestrian and bicycle trips are generated by the adjacent
homes, offices, and Class I trails.
The E&TS indicates that the critical speed on Arnold Road between Dublin Boulevard and Central
Parkway is 38 mph. The critical speed on Arnold Road between Central Parkway and Gleason
Drive is 40 mph. This suggests that the posted speed limit on Arnold Road between Dublin
Boulevard and Gleason Drive should be set at 40 mph when rounded to the nearest 5 mph
increment. However, due to the above-mentioned land use and roadway characteristics, the
E&TS, in compliance with CVC Sections 627, 22358.5 and 21400(b) and CA MUTCD Section 2B.13,
recommends that the posted speed limit be established at 35 mph by applying the optional 5 mph
reduction in speed limit.
Tassajara Road between Dublin Boulevard and Gleason Drive
Tassajara Road is classified as a principal arterial in the City of Dublin’s Roadway Classification
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Page 3 of 4
System. Land uses such as high-density residential development, commercial developments, and
Emerald Glen Park on the west side of Tassajara Road result in increased pedestrian and bicycle
activity. Several schools are also located within ¼ to ¾ mile on the east side, and there are
marked yellow school crosswalks at the Tassajara Road and Gleason Drive intersection. In
addition, Tassajara Road south of the subject segment, which is south of Dublin Boulevard, has a
lower posted speed limit of 35 mph. Reducing the speed limit from 45 mph to 40 mph for the
subject segment will provide a smoother transition between speed limits.
The E&TS indicates that the critical speed on the Tassajara Road segment between Dublin
Boulevard and Central Parkway is 40 mph and 45 mph in the segment between Central Parkway
and Gleason Drive. This suggests that the posted speed limit on Tassajara Road between Dublin
Boulevard and Gleason Drive should be 45 mph when rounded to the nearest 5 mph increment.
However, due to the above-mentioned land use and roadway characteristics, the E&TS, in
compliance with CVC Sections 627, 22358.5 and 21400(b) and CA MUTCD Section 2B.13,
recommends that the posted speed limit be established at 40 mph by applying the optional 5 mph
reduction in speed limit.
Tassajara Road between Fallon Road and the northern City limit:
Roadway characteristic changes in this segment of Tassajara Road include increased bicycle and
pedestrian usage due to the addition of Class II bike lanes, a Class I trail on the west side from
Fallon Road to Kylemore Circle, and new crosswalks at the intersections of Tassajara Road and
Palisades Drive and Tassajara Road and Fallon Road. Land use changes include new single-family
residential units on both the east and west sides of Tassajara Road. Pedestrian and bicycle trips
are generated by the adjacent homes and Class I trails. In addition, the street segment to the
north, Camino Tassajara in Contra Costa County, has a speed limit of 40 mph. The street segment
to the south, which is Fallon Road, also has a speed limit of 40 mph. A speed reduction in the
subject segment from 45 mph to 40 mph will allow for a smoother transition between the
segments.
The E&TS indicates that the critical speed on the Tassajara Road segment between Fallon Road
and the northern City limit is 44 mph. This suggests that the posted speed limit should be 45 mph
when rounded to the nearest 5 mph increment. However, due to the above-mentioned land use
and roadway characteristics, the E&TS, in compliance with CVC Sections 627, 22358.5 and
21400(b) and CA MUTCD Section 2B.13, recommends that the posted speed limit be established at
40 mph by applying the optional 5 mph reduction in speed limit.
The Traffic Safety Committee supported the reduction in speed limits at its February 24, 2021
meeting.
STRATEGIC PLAN INITIATIVE:
None.
NOTICING REQUIREMENTS/PUBLIC OUTREACH:
The City Council Agenda was posted.
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Page 4 of 4
ATTACHMENTS:
1) Ordinance Amending the Dublin Traffic Code to Reduce the Speed Limits on Segments of
Arnold Road and Tassajara Road
2)Engineering and Traffic Surveys (E&TS) for Arnold Road and Tassajara Road
3) Exhibit showing the existing and proposed changes to the subject segments
4) Ordinance 8-00
5) Ordinance 17-03
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Attachment 1
Ord. No. XX-21, Item X.X, Adopted XX/XX/21 Page 1 of 2
ORDINANCE NO. XX – 21
AN ORDINANCE OF THE CITY COUNCIL
OF THE CITY OF DUBLIN
AMENDING THE DUBLIN TRAFFIC CODE TO REDUCE THE SPEED LIMITS ON
SEGMENTS OF ARNOLD ROAD AND TASSAJARA ROAD
The City Council of the City of Dublin does hereby ordain as follows:
Section 1: The following language shall be removed from Section 6.60.040 of the City of
Dublin Traffic Code- Forty Miles Per Hour:
“Arnold Road: Dublin Boulevard to Gleason Drive (Ord. 8-00)”
Section 2: The following language shall be modified in Section 6.60.050 of the City of
Dublin Traffic Code- Forty-Five Miles Per Hour:
From “Tassajara Road: Dublin Blvd. to City Limit (Ord. 17-03)”
To “Tassajara Road: Gleason Drive to Fallon Road (Ord. 17-03)”
Section 3: The following language shall be added to Section 6.60.030 of the City of
Dublin Traffic Code- Thirty-Five Miles Per Hour:
“Arnold Road: Dublin Boulevard to Gleason Drive”
Section 4: The following language shall be added to Section 6.60.040 of the City of
Dublin Traffic Code- Forty Miles Per Hour:
“Tassajara Road: Dublin Boulevard to Gleason Drive”
“Tassajara Road: Fallon Road to Northern City Limit”
Section 5: Severability. The provisions of this Ordinance are severable and if any
provision, clause, sentence, word, or part thereof is held illegal, invalid, unconstitutional, or
inapplicable to any person or circumstances, such illegality, invalidity, unconstitutionality, or
inapplicability shall not affect or impair any of the remaining provisions, clauses, sentences,
sections, word or parts thereof of the ordinance or their applicability to other persons or
circumstances.
Section 6: Effective Date. The Ordinance shall take effect and be enforced thirty (30)
days following its adoption and following placement of speed limit signs providing notice thereof.
Section 5: Posting. The City Clerk of the City of Dublin shall cause this Ordinance to be
posted in at least three (3) public places in the City of Dublin in accordance with Section 36933
of the Government Code of the State of California.
87
Attachment 1
Ord. No. XX-21, Item X.X, Adopted XX/XX/21 Page 2 of 2
PASSED, APPROVED AND ADOPTED this ___ day of ____ 2021, by the following vote:
AYES:
NOES:
ABSENT:
ABSTAIN:
______________________________
Mayor
ATTEST:
_________________________________
City Clerk
88
Dublin Speed Limits
Engineering & Traffic Surveys
Proposed Speed Limit Changes
For
Arnold Road
Between Dublin Blvd. and Gleason Dr.
Tassajara Road
Between Dublin Blvd. and Gleason Dr.
And
Between Fallon Rd. and City Limit
Prepared For:
The City of Dublin, CA
FINAL REPORT
March 30, 2021
Prepared By:
GHD, Inc.
2300 Clayton Rd., Suite 920
Concord, CA 94520
Attachment 2
89
DUBLIN SPEED LIMITS
ENGINEERING & TRAFFIC SURVEYS
For
Arnold Road (Between Dublin Blvd. and Gleason Dr.),
Tassajara Road (Between Dublin Blvd. and Gleason Dr.), &
Tassajara Road (Between Fallon Rd. and City Limit)
Prepared For
THE CITY OF DUBLIN, CA
FINAL REPORT
March 30, 2021
Prepared By
GHD
2300 Clayton Road, Suite 920
Concord, CA 94520
www.GHD.com
11159184 0601
(R11159184-0601A-TIA002.DOC)
90
March 2021
Dublin Speed Limits E&TS Report 11159184-0601A / 2592
INTRODUCTION
The following report presents the findings of an “Engineering and Traffic Speed Survey” study with
recommended new speed limits for the following roadway segments in the City of Dublin CA:
Arnold Road (between Dublin Blvd. and Gleason Dr.),
Tassajara Road (between Dublin Blvd. and Gleason Dr.), and
Tassajara Road (between Fallon Rd. and north City Limit)
The recommended speed limit s have been based on survey data, including rada r speed
measurements, field observations of street characteristics, and a review of the collision history.
The speed surveys identified the “85th-percentile speed” (or “critical speed”), which is defined as the
speed at which 85 percent of the drivers are traveling at o r below. Speed limits are generally
established by analysis of the surveyed 85th-percentile speeds in combination with the observed
street characteristics. Ultimately, the designation of safe and efficient speed limits should be based
on sound engineering judgment. Additional input from the City Traffic Safety Committee was also
provided regarding the recommendations.
RESULTS/RECOMMENDATIONS
Based on the evaluated data, it is recommended the following speed limit changes be established:
Arnold Road Existing Recommended
between Dublin Blvd. and Central Pkwy.: 40 mph 35 mph (New)
between Central Pkwy. and Gleason Dr.: 40 mph 35 mph (New)
Tassajara Road Existing Recommended
between Dublin Boulevard and Gleason Drive: 45 mph 40 mph (New)
between Fallon Road and north City Limit: 45 mph 40 mph (New)
BACKGROUND METHODOLOGY
In order to set and maintain speed limits on City streets, Engineering & Traffic Speed Surveys (or
“E&TS” surveys) must be periodically conducted as set forth in the California State Vehicle Code in
order to provide proper and enforceable speed limits. Speed limits are set based on various factors,
including measured speeds, physical roadway attributes, collision history, daily traffic volumes, and
adjacent land uses.
The California State Vehicle Code (sections 40802 & 40803) defines when engineering & traffic
speed surveys must be conducted.1 In general, a City with an on-going program in place which
incorporates several criteria (including training of police officers in correct radar operation, radar
devices that meet operational standards, and have been calibrated within three years of the alleged
violation) can survey a street every seven years. If a registered engineer “determines that no
significant changes in roadway or traffic conditions have occurred, including, but not limited to,
changes in adjoining property or land use, roadway width, or traffic volumes”, then the timeframe
can be extended to ten years.
Some road types are exempt from the above requirements and have inherent prima facie speed limits
unless a different speed is determined by local authority. For example, a 25 mph speed limit is
presumed for school zones, strictly local roads, and in a business or residential district. The California
Manual on Uniform Traffic Control Devices (CaMUTCD) provides the procedures for preparing an
engineering & traffic survey.2
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DATA COLLECTION
The data collection for the analyses included radar speed surveys and identifying the roadway
characteristics.3 The roadway characteristics included alignment, street parking, adjacent land use,
and level of side-street activity. The speed surveys recorded 200 observations, which meets or
exceeds the CaMUTCD recommended guidelines.
The total number of collisions and the number of speed related collisions were identified over a
three year period (1/1/17-12/31/19). The collision rate, expressed in terms of the number of
collisions per million vehicle miles of travel, was calculated and compared to the statewide average
rate for similar streets.4
An Engineering & Traffic Survey worksheet was completed for each segment. The E&TS worksheet
contains information that includes posted speed limit, measured critical speed, roadway
characteristics, collision rates, and the survey recommendations. Supplementary E&TS worksheets
were also provided to provide further explanation regarding conditions that may not be readily
apparent.
References
1. California Department of Motor Vehicles, Vehicle Code, Sections 40802-40803, 2020.
2. California Manual on Uniform Traffic Control Devices, 2014 Edition, Revision 5 (March 27, 2020).
3. GHD Inc., Radar Speed Surveys and Field Analysis conducted January 13-20, 2021.
4. California Department of Transportation, 2017 Collision Data on California State Highways, Business,
Transportation, and Housing Agency, Division of Traffic Operations, Sacramento, CA.
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Engineering & Traffic Surveys
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Arnold Road (between Dublin Blvd. and Gleason Dr.)
This segment of Arnold Road is oriented in a north -south direction between Dublin Boulevard and
Gleason Drive. It consists of one through lane in each direction , with a center median and additional
turn lanes at the intersections between Dublin Boulevard and Central Parkway, then yellow
centerline striping between Central Parkway and Gleason Drive. It is straight and flat with striped
bicycle lanes. It is classified as a minor arterial street in the City of Dublin Street Functional
Classification System. The adjacent land uses have recently undergone several changes. A new
residential neighborhood is being constructed along the west side, with some units completed and
others still under construction. A commercial office building is under construction on the east side
between Dublin Boulevard and Central Parkway. Several int ersection-design changes have also
been implemented. A new access road to the residential neighborhood extends west from the
Arnold Road/Central Parkway intersection, creating a signalized four-leg intersection. Another new
access road (Horizon Parkway) e xtends west from Arnold Road, creating a new three-leg signalized
intersection, between Central Parkway and Gleason Drive. As a result of the roadway changes, all
street parking has been prohibited (previously allowed between Dublin Boulevard and Central
Parkway). At the Arnold Road/Dublin Boulevard intersection there is a Class 1 multi-use trail along
the north side of Dublin Boulevard that crosses Arnold Road. The construction of new residential,
office, and nearby retail businesses, and proximity of the Dublin/Pleasanton BART station to the
south, is generating increasing levels of pedestrian and street-crossing activity.
Speed Data
The segment has an existing speed limit of 40 mph. There are two northbound speed limit signs
located between Dublin Boulevard and Central Parkway, and there is another northbound sign
located north of Central Parkway. There is a southbound sign located south of Gleason Drive and
another sign located south of Horizon Parkway. The measured 85th-percentile speeds were
recorded as follows:
Speed 85th % Recommended
Arnold Road: Limit Speed Speed Limit
Dublin Blvd. to Central Pkwy. 40 mph 38.0 mph 35 mph (New)
Central Pkwy. to Gleason Dr. 40 mph 40.0 mph 35 mph (New)
Recommendation
Based on the measured 85th-percentile speed and existing street characteristics, it is recommended
the speed limit be established at 35 mph. Factors include the proximity of new residential uses, with
associated pedestrian and bicycle activity, including increased pedestrian crossing volumes at new
and redesigned intersections and Class 1 trail crossing; and increased traffic volume growth from
the new residential and commercial businesses. Therefore, it is recommended that an optional
5 mph reduction from the nearest rounded 85 th-percentile speed of 40 mph be implemented,
resulting in a 35 mph speed limit (new).
Improvements
Replace the existing “40 mph speed limit” signs with new “35 mph speed limit” signs (type R2-1 per
CaMUTCD).
94
CITY OF DUBLIN
SPEED LIMIT
ENGINEERING / TRAFFIC SURVEY
Street: Arnold Road Limits: between Dublin Blvd. and Gleason Dr.
Length (feet): 2,800’ / 0.53 mi
SPEEDS
Location of Survey: Dublin Blvd. to Central Pkwy.
500’ n/o Dublin Blvd.
Central Pkwy to Gleason Dr
600’ s/o Gleason Dr.
Date Taken: 1/20/21 1/20/21
Posted Speed: 40 mph 40 mph
Pace Speed: 27-36 mph 31-40 mph
% in Pace, Above, Below 77; 19; 4 81; 12; 7
Critical Speed (85%) 38.0 mph 40.0 mph
Range of Speeds 25-47 mph 25-49 mph
ROADWAY DESIGN AND TRAFFIC CHARACTERISTICS
Width (ft.): 42’-82’ No. Lanes: 2 (1 NB & 1 SB) Classification: Minor Arterial
Average Daily Traffic: 8,516 Date Taken: 4/27/2016
Special Conditions (Parking, Roadway Alignment, Land Use, School Area, etc.): mostly flat
and straight; raised center medians and centerline striping; parking not allowed; striped bicycle
lanes; new residential development on west side and new commercial development on east
side; new cross-streets and intersections providing access to the new residential neighborhood
on west side; increased pedestrian/bicycle crossing activity as a result of new development;
Class l trail crossing at the Dublin Blvd. intersection.
ACCIDENT CHARACTERISTICS
Accident Period Analyzed: 1/1/17 – 12/31/19
Number of Accidents (List Total and Each Year): 3 (’17 = 0, ‘18 = 2, ‘19 = 1)
Number of Speed Related Accidents (Total and Each Year): 0 (‘17 = 0, ‘18 = 0, ‘19 = 0)
Calculated Accident Rate: 0.61 acc./m.v.m. Statewide Average Rate: 1.20 acc./m.v.m.
SURVEY RESULTS
Recommendations: Based on the measured critical speeds and
roadway characteristics, including new residential and office
developments; new cross-streets and intersections; Class l trail
crossing; and increased traffic volumes and pedestrian/bicycle
activity, it is recommended that an optional 5 mph downward
speed zoning be applied to the nearest rounded 85th % speed of
40 mph, establishing a 35 mph speed limit (New).
Study Prepared By: GHD Inc.
Date: March 30, 2021
Approved By: Date
Ms. Sai Midididdi, T.E.
Associate Civil Engineer (Traffic)
City of Dublin, CA
Approved Speed Limit: 35 mph
Per CVC 40803, Survey Expires: 95
CITY OF DUBLIN
SUPPLEMENTAL HIGHWAY, TRAFFIC, AND ROADSIDE CONDITIONS
ENGINEERING / TRAFFIC SURVEY
Street: Arnold Road Limits: between Dublin Blvd. and Gleason Dr.
CONDITIONS NOT NECESSARILY APPARENT TO DRIVER & PEDESTRIAN/BICYCLIST SAFETY
ADJACENT LAND USE
Marked ‘X’ if YES
Pre-School/Nursery/Daycare
Elementary School
Middle School
High School
Senior Center / Facility
Hospital / Medical Office
Retail/Commercial Activity
X Recreation: Park/Playground/Sports Field Class 1 trail with trail crossing.
X Other New residential neighborhood on west side; and new office complex on east side.
ROADWAY CHARACTERISTICS
Roadway Horizontal Alignment Change
Roadway Vertical Alignment Change
Narrow Lanes (< 12 feet wide)
X Bicycle Lanes and/or Bicycle Activity
Designated Safe-Route-to-School
Designated Truck Route
X Designated Bus Route
X Other New cross-streets and intersections serving new residential neighborhood on west side.
Increased pedestrian volumes and street crossings associated with new residential, office,
and retail construction, as well as to/from BART station located to the south.
PARKING & SIDE STREET CHARACTERISTICS
On-Street Parking Allowed
Parking Occupancy High Medium Low
Parking Turnover High Medium Low
X Commercial Driveways. Activity: High X Medium Low
X Residential Units/Neighborhoods Located on Side-Streets
Direct Residential Driveway Access With Vehicles Turning In & Backing Out
96
Street: Arnold Road Limits: between Dublin Blvd. and Gleason Dr.
DENSITY OF RESIDENTIAL UNITS
Do any of the following characteristics apply?
Marked ‘X’ if YES
(A) Upon one side of the highway, within a distance of a quarter mile, the
contiguous property fronting thereon is occupied by 13 or more separate
dwelling houses or business structures. Or
(B) Upon both sides of the highway, collectively, within a distance of a
quarter of a mile, the contiguous property fronting thereon is occupied by
16 or more separate dwelling houses or business structures. Or
The portion of highway is longer than one-quarter of a mile, but has the
ratio of separate dwelling houses or business structures to the length
of the highway described in either subparagraph (A) or (B).
RECOMMENDED SPEED LIMIT
Based on the surveyed speed data and roadway characteristics in accordance with the
guidelines for establishing speed limits as outlined in the California Manual on Uniform Traffic
Control Devices (2014 Edition, Revision 5, Chapter 2B), application of a 5 mph reduction from
the nearest rounded 85th percentile speed of 40 mph for roadside conditions not readily
apparent to a driver is appropriate. Therefore the recommended speed limit is: 35 mph
Per CVC 40803, Survey Expires:
Approved By:
Ms. Sai Midididdi, T.E.
Associate Civil Engineer (Traffic)
City of Dublin, CA
Authorized Signature:
Date:
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Tassajara Road (between Dublin Boulevard and Gleason Drive)
This segment of Tassajara Road extends in a north -south direction between Dublin Boulevard and
Gleason Drive. It consists of four to ten lanes includ ing turn lanes at intersections. The segment is
straight and flat with the travel directions separated by center medians. There are striped bicycle
lanes and parking is not allowed. It is classified as a principal arterial street in the City of Dublin
Street Functional Classification System. It is also a designated Truck Route (Tassajara Road is a
designated Truck Route between I-580 and Gleason Drive). Adjacent land uses consist of
commercial/retail businesses on the west side between Dublin Boulevard and Central Parkway with
access driveways and vehicles turning in and out. There is also a multi-unit residential complex
located at the southwest corner of the Tassajara Road/Central Parkway intersection. And there is a
large community park (Emerald Glen Park) with sports fields and aquatic complex located on the
west side between Central Parkway and Gleason Drive. Several schools are located within ¼ - ¾
mile on the east side, and there are yellow school crosswalks at the Tassajara Rd./Gleason Dr.
intersection. Pedestrian and bicycle trips are generated by the adjacent park, residential, and school
uses.
Speed Data
This segment of Tassajara Road has an existing speed limit of 45 mph. A southbound 45 mph
speed limit sign is located south of Gleason Dr ive. There are no northbound speed limit signs on
the segment between Dublin Boulevard and Gleason Drive. The measured 85th-percentile speed
was recorded as follows:
Speed 85th % Recommended
Tassajara Road: Limit Speed Speed Limit
Dublin Boulevard to Central Pkwy. 45 mph 40.0 mph 40 mph (New)
Central Pkwy. to Gleason Dr. 45 mph 45.0 mph 40 mph (New)
Recommendation
Based on the measured 85 th-percentile speed and existing street characteristics, it is recommended
that a new speed limit of 40 mph be established for this segment of Tassajara Road. The segment
serves as a transition zone between lower 85 th-percentile speeds south of Dublin Boulevard and
higher 85th-percentile speeds north of Gleason Drive. Additional f actors include continuing
development with associated vehicle and pedestrian traffic along the corridor, including the Emerald
Glen Park complex; vehicles turning in and out of commercial driveways along the segment; and
variable traffic conditions with higher-speed vehicles approaching frequently stopped/queued traffic
at the intersection approaches. Therefore, it is recommended that an optional 5 mph reduction from
the highest rounded 85th-percentile speed of 45 mph be implemented, resulting in a new 40 mph
speed limit (change from existing 45 mph speed limit).
Improvements
Install a northbound “40 mph speed limit” sign (type R2-1 per CaMUTCD) north of Dublin Boulevard
and a southbound “40 mph speed limit” sign south of Gleason Drive (remove the existing
southbound 45 mph sign).
100
CITY OF DUBLIN
SPEED LIMIT
ENGINEERING / TRAFFIC SURVEY
Street: Tassajara Road Limits: between Dublin Blvd. and Gleason Dr.
Length (feet): 2.500’ / 0.48 mi
SPEEDS
Location of Survey: Dublin Blvd. to Central Pkwy.
500’ n/o Dublin Blvd.
Central Pkwy. to Gleason Dr.
500’ s/o Gleason Dr.
Date Taken: 1/14/21 1/19/21
Posted Speed: 45 mph 45 mph
Pace Speed: 31-40 mph 36-45 mph
% in Pace, Above, Below 68; 15; 17 75; 11; 14
Critical Speed (85%) 40.0 mph 45.0 mph
Range of Speeds 22-48 mph 27-52 mph
ROADWAY DESIGN AND TRAFFIC CHARACTERISTICS
Width (ft.): 100’-150’ No. Lanes: 4-10 (2-5 NB & 2-8 SB) Classification: Principal Arterial
Average Daily Traffic: 25,363 Date Taken: 4/16/19
Special Conditions (Parking, Roadway Alignment, Land Use, School Area, etc.): straight and flat;
center medians; striped bicycle lanes; parking not allowed; adjacent retail, multi-unit residential,
community park and aquatic complex; nearby schools; designated truck route; variable traffic
conditions with mix of higher speed through traffic and stopped/queued vehicles on approaches
to intersections.
ACCIDENT CHARACTERISTICS
Accident Period Analyzed: 1/1/17 – 12/31/19
Number of Accidents (List Total and Each Year): 12 (’17 = 2, ‘18 = 4, ‘19 = 6)
Number of Speed Related Accidents (Total and Each Year): 6 (‘17 = 1, ‘18 = 1, ‘19 = 4)
Calculated Accident Rate: 0.90 acc./m.v.m. Statewide Average Rate: 3.02 acc./m.v.m.
SURVEY RESULTS
Recommendations: Based on the measured critical speed and
roadway characteristics, including adjacent community park,
aquatic complex, retail, residential, and nearby school uses with
pedestrian & bicycle activity; and variable traffic conditions with
mix of higher speed vehicles and frequently stopped/queued
vehicles, it is recommended that an optional downward speed
zoning be applied to the highest rounded 85th % speed of
45 mph, establishing a 40 mph speed limit (New).
Study Prepared By: GHD Inc.
Date: March 30, 2021
Approved By: Date
Ms. Sai Midididdi, T.E.
Associate Civil Engineer (Traffic)
City of Dublin, CA
Approved Speed Limit: 40 mph
Per CVC 40803, Survey Expires:
101
CITY OF DUBLIN
SUPPLEMENTAL HIGHWAY, TRAFFIC, AND ROADSIDE CONDITIONS
ENGINEERING / TRAFFIC SURVEY
Street: Tassajara Road Limits: between Dublin Blvd. and Gleason Dr.
CONDITIONS NOT NECESSARILY APPARENT TO DRIVER & PEDESTRIAN/BICYCLIST SAFETY
ADJACENT LAND USE
Marked ‘X’ if YES
Pre-School/Nursery/Daycare
Elementary School
Middle School
High School
Senior Center / Facility
Hospital / Medical Office
X Retail/Commercial Activity
X Recreation: Park/Playground/Sports Field Community park, sports fields, aquatic complex.
X Other Residential complex at Central Prkwy. and residential neighborhoods at Gleason Drive.
Schools east of Tassajara Road and school crosswalks at Gleason Drive intersection.
ROADWAY CHARACTERISTICS
Roadway Horizontal Alignment Change
Roadway Vertical Alignment Change
Narrow Lanes (< 12 feet wide)
X Bicycle Lanes and/or Bicycle Activity
Designated Safe-Route-to-School
X Designated Truck Route
X Designated Bus Route
X Other Variable traffic conditions with higher speed vehicles and frequently stopped and queued
vehicles at the approaches to intersections.
PARKING & SIDE STREET CHARACTERISTICS
On-Street Parking Allowed
Parking Occupancy High Medium Low
Parking Turnover High Medium Low
X Commercial Driveways. Activity: X High Medium Low
X Residential Units/Neighborhoods Located on Side-Streets
Direct Residential Driveway Access With Vehicles Turning In & Backing Out
102
Street: Tassajara Road Limits: between Dublin Blvd. and Gleason Dr.
DENSITY OF RESIDENTIAL UNITS
Do any of the following characteristics apply?
Marked ‘X’ if YES
(A) Upon one side of the highway, within a distance of a quarter mile, the
contiguous property fronting thereon is occupied by 13 or more separate
dwelling houses or business structures. Or
(B) Upon both sides of the highway, collectively, within a distance of a
quarter of a mile, the contiguous property fronting thereon is occupied by
16 or more separate dwelling houses or business structures. Or
The portion of highway is longer than one-quarter of a mile, but has the
ratio of separate dwelling houses or business structures to the length
of the highway described in either subparagraph (A) or (B).
RECOMMENDED SPEED LIMIT
Based on the surveyed speed data and roadway characteristics in accordance with the
guidelines for establishing speed limits as outlined in the California Manual on Uniform Traffic
Control Devices (2014 Edition, Revision 5, Chapter 2B), application of a 5 mph reduction from
the nearest rounded 85th percentile speed of 45 mph for roadside conditions not readily
apparent to a driver is appropriate. Therefore the recommended speed limit is: 40 mph
Per CVC 40803, Survey Expires:
Approved By:
Ms. Sai Midididdi, T.E.
Associate Civil Engineer (Traffic)
City of Dublin, CA
Authorized Signature:
Date:
103
March 2021
Dublin Speed Limits E&TS Report 11159184-0601A / 2592
Tassajara Road (between Fallon Road and City Limit)
This segment of Tassajara Road extends between Fallon Road and the north City Limit. It is
oriented in a primarily north-south direction and consists of two broad horizontal curves through the
segment. It consists of four lanes from Fallon Road to Palisades Drive, then transitions to two lanes
to the City Limit boundary. There are striped bicycle lanes and sidewalks south of Palisades Drive,
then transitions to narrow unimproved shoulder areas to the City Limit. There are “Share the Road”
warning signs for bicyclists on the unimproved section. Street parking is not allowed. The street is
classified as a minor arterial in the City of Dublin Street Functional Classification System . Adjacent
land uses consist of newly built residential neighborhoods accessed via side streets (no direct
access) and undeveloped land near the City Limit. A Class 1 trail paralleling Palisades Drive going
into the neighborhood connects to Tassajara Road south of the Palisades Drive intersection. The
sidewalk on the south side of Fallon Road beginning from Tassajara Road is als o a Class 1 trail.
Speed Data
The segment has an existing speed limit of 45 mph. There are currently no visible speed limit signs
on the segment. There is an existing southbound 45 mph speed limit sign with accompanying
“Speed Checked By Radar” sign located south of the City Limit, but there is a c overing over it so the
sign is not visible. The speed limit north and south of the segment is 40 mph. (There are 40 mph
speed limit signs just north of the City Limit and on Fallon Road south of the Tassajara Road/Fallon
Road intersection.) Speed surveys were conducted at two locations. The measured 85 h-percentile
speeds were recorded as follows:
Speed 85th % Recommended
Tassajara Road: Limit Speed Speed Limit
Fallon Rd. to Palisades Dr.-Kylemore Entry 45 mph 44.0 mph 40 mph (New)
Palisades Dr.-Kylemore Entry to City Limit 45 mph 44.0 mph 40 mph (New)
Recommendation
Based on the measured speed s and existing street characteristics, it is recommended the speed
limit be established at 40 mph. Factors include the roadway curvature combined with the transition
from four lanes to two lanes that has narrow unimproved shoulder areas with bicycles sharing the
roadway. The adjacent newly built residential neighborhoods generate bicycle and pedestrian
activity. Therefore, it is recommended that an optional 5 mph reduction from the near est rounded
85th-percentile speed of 45 mph be implemented, resulting in a new 40 mph speed limit (change
from existing 45 mph speed limit).
Improvements
Install “40 mph speed limit” signs (type R2-1 per CaMUTCD) on the segment (remove the existing
southbound 45 mph sign).
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CITY OF DUBLIN
SPEED LIMIT
ENGINEERING / TRAFFIC SURVEY
Street: Tassajara Road Limits: between Fallon Rd. and City Limit
Length (feet): 2.600’ / 0.50 mi
SPEEDS
Location of Survey: Fallon Rd. to Palisades Dr.
300’ s/o Palisades Dr.
Palisades Dr. to City Limit
900’ n/o Palisades Dr.
Date Taken: 1/14/21 1/19/21
Posted Speed: 45 mph 45 mph
Pace Speed: 36-45 mph 36-45 mph
% in Pace, Above, Below 75; 5; 20 86; 9; 5
Critical Speed (85%) 44.0 mph 44.0 mph
Range of Speeds 28-51 mph 31-50 mph
ROADWAY DESIGN AND TRAFFIC CHARACTERISTICS
Width (ft.): 26’-116’ No. Lanes: 2-4 (1-2 NB & 1-2 SB) Classification: Minor Arterial
Average Daily Traffic: 10,855 Date Taken: 4/16/19
Special Conditions (Parking, Roadway Alignment, Land Use, School Area, etc.): straight and
curved sections; through lanes taper from four to two lanes between Palisades Dr and City Limit
with unimproved shoulders; bicycles share the roadway on unimproved section; parking not
allowed; adjacent residential neighborhoods (no direct access) and Class 1 trails generate
bicycle and pedestrian activity.
ACCIDENT CHARACTERISTICS
Accident Period Analyzed: 1/1/17 – 12/31/19
Number of Accidents (List Total and Each Year): 5 (’17 = 3, ‘18 = 0, ‘19 = 2)
Number of Speed Related Accidents (Total and Each Year): 2 (‘17 = 2, ‘18 = 0, ‘19 = 0)
Calculated Accident Rate: 0.84 acc./m.v.m. Statewide Average Rate: 0.82 acc./m.v.m.
SURVEY RESULTS
Recommendations: Based on the measured critical speed and
roadway characteristics, including curved sections with
unimproved shoulder areas where bicycles share roadway;
and new residential areas generating additional bicycle and
pedestrian activity, it is recommended that an optional 5 mph
downward speed zoning be applied to the nearest rounded 85th %
speed of 45 mph, establishing a 40 mph speed limit (New).
Study Prepared By: GHD Inc.
Date: March 30, 2021
Approved By: Date
Ms. Sai Midididdi, T.E.
Associate Civil Engineer (Traffic)
City of Dublin, CA
Approved Speed Limit: 40 mph
Per CVC 40803, Survey Expires:
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CITY OF DUBLIN
SUPPLEMENTAL HIGHWAY, TRAFFIC, AND ROADSIDE CONDITIONS
ENGINEERING / TRAFFIC SURVEY
Street: Tassajara Road Limits: between Fallon Rd. and City Limit
CONDITIONS NOT NECESSARILY APPARENT TO DRIVER & PEDESTRIAN/BICYCLIST SAFETY
ADJACENT LAND USE
Marked ‘X’ if YES
Pre-School/Nursery/Daycare
Elementary School
Middle School
High School
Senior Center / Facility
Hospital / Medical Office
Retail/Commercial Activity
X Recreation: Park/Playground/Sports Field Class 1 trails on Tassajara, Palisades, & Fallon.
X Other Newly built residential neighborhoods.
ROADWAY CHARACTERISTICS
X Roadway Horizontal Alignment Change
X Roadway Vertical Alignment Change
Narrow Lanes (< 12 feet wide)
X Bicycle Lanes and/or Bicycle Activity
Designated Safe-Route-to-School
Designated Truck Route
X Designated Bus Route
X Other Narrow shoulders on segment with bicycles sharing the roadway.
Increased pedestrian volumes and street-crossings associated with new residential units.
PARKING & SIDE STREET CHARACTERISTICS
On-Street Parking Allowed
Parking Occupancy High Medium Low
Parking Turnover High Medium Low
Commercial Driveways. Activity: High Medium Low
X Residential Units/Neighborhoods Located on Side-Streets
Direct Residential Driveway Access With Vehicles Turning In & Backing Out
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Street: Tassajara Road Limits: between Fallon Rd. and City Limit
DENSITY OF RESIDENTIAL UNITS
Do any of the following characteristics apply?
Marked ‘X’ if YES
(A) Upon one side of the highway, within a distance of a quarter mile, the
contiguous property fronting thereon is occupied by 13 or more separate
dwelling houses or business structures. Or
(B) Upon both sides of the highway, collectively, within a distance of a
quarter of a mile, the contiguous property fronting thereon is occupied by
16 or more separate dwelling houses or business structures. Or
The portion of highway is longer than one-quarter of a mile, but has the
ratio of separate dwelling houses or business structures to the length
of the highway described in either subparagraph (A) or (B).
RECOMMENDED SPEED LIMIT
Based on the surveyed speed data and roadway c haracteristics in accordance with the
guidelines for establishing speed limits as outlined in the California Manual on Uniform Traffic
Control Devices (2014 Edition, Revision 5, Chapter 2B), application of a 5 mph reduction from
the nearest rounded 85th percentile speed of 45 mph for roadside conditions not readily
apparent to a driver is appropriate. Therefore the recommended speed limit is: 40 mph
Per CVC 40803, Survey Expires:
Approved By:
Ms. Sai Midididdi, T.E.
Associate Civil Engineer (Traffic)
City of Dublin, CA
Authorized Signature:
Date:
109