HomeMy WebLinkAbout2017-03-06; Traffic Safety Commission; ; Establish a prima facie speed limit upon Estrella de Mar Roadfrom Alga Road to 675 feet north of Beryl WayCITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
COMMISSION MEETING OF: -March 6, 2017 ITEM NO. 6-A-1
LOCATION: Estrella de Mar Road between Alga Road and Beryl Way
INITIATED BY: Bahram Hajialilou
REQUESTED ACTION: Establish a prima facie speed limit upon Estrella de Mar Road
from Alga Road to 675 feet north of Beryl Way.
BACKGROUND:
The portion of Estrella de Mar Road north of Alga Road was fully opened to traffic in
2010, and the portion between Dove Lane and Alga Road was constructed earlier (see
attached Exhibit 1). A prima facie speed limit needs to be established for this roadway
section. The roadway section directly to the north, which connects to Poinsettia Lane,
qualifies as a Residence District per the California Vehicle Code and is posted at 25 miles
per hour.
SETTING SPEED LIMITS:
A fundamental tenet is that laws are enacted to protect the majority of the public by
regulating the unsafe or unreasonable actions of the few. Establishing defensible speed
limits and installing appropriate signage is critical to successful police enforcement. City
staff follows the California Vehicle Code and Caltrans criteria to propose a legally
defensible speed limit.
In some cases a road meets specific criteria established in the California Vehicle Code
and a default speed limit is established without city council action. For example, a road
that meets the specific criteria to be classified as a resident district can have a posted
speed limit of 25 mph.
In other cases, a "prima facie" speed limit must be established according to the
California Vehicle Code that calls for speed limits to be based on the reasonable speed
for a driver to operate a vehicle under ideal conditions in off-peak free flowing
conditions. City staff use the Caltrans criteria to determine this reasonable speed and
propose a recommended speed limit. Based on staff recommendations, the City Council
adopts an ordinance establishing the speed limit at a public meeting. Appropriate
regulatory speed limit signs are then posted in compliance with the California Manual
on Uniform Traffic Control Devices (CAMUTCD). Police can cite violators that exceed the
posted speed limit with confidence the citation will be upheld in court. When speed
limits have been reasonably set, the enforcement efforts of the Carlsbad Police
Department are more effective.
Among many factors, the three most persuasive issues considered when setting a
realistic, or rational, speed limit are:
1. g5th percentile speed (critical speed)
2. Collision history
3. Conditions that may not be readily apparent to the driver
The premise implied in speed zoning is that 85% (eighty-five percent) of the drivers
operate their vehicles at a reasonable speed. The g5th percentile speed, often referred
to as the "critical speed", is the speed which 85% of the drivers are traveling at or
below. Drivers that operate their vehicle at speeds higher than the g5th percentile speed
are considered to be driving at an excessive speed. The speed limit is set at the five mph
increment that is at or just below this critical speed-unless there are conditions not
readily apparent to the driver (e.g., an unusual collision history).
A comprehensive review of the collision history on a roadway is another important
element in the process to establish a speed limit. In the collision analysis, factors such
as collision frequency, type, severity, road conditions, road geometry, lighting
conditions, and spatial distribution of the collisions are all considered. The review of
collisions will also reveal if there is a high incidence of speed-related collisions on the
road at specific locations. However, absent a significant collision history attributed to
speed, it may be concluded that drivers are operating their vehicle in a reasonable and
prudent manner at a speed at or below the critical speed used to establish the speed
limit. If the collision history supports a lower speed limit, or there exist other conditions
not readily apparent to the driver, the speed limit can be established using a speed that
is 5 mph below the critical speed.
Speed limits should not be lowered for conditions that are readily apparent to the
driver, such as driveways with direct access to the road. Conditions not readily apparent
to the driver can be used to lower the speed limit an additional 5 mph, but are
sometimes successfully challenged in court. For unusual conditions or conditions not
readily apparent to motor vehicle operators, appropriate warning devices should be
considered in lieu of lowering the speed limit.
Voluntary public compliance with the posted speed limit is the goal of determining and
posting a realistic prima facie speed limit. A speed limit based on the critical speed
provides for the regulation of unreasonable behavior by a few individuals. A legally
defensible speed limit is based on a factual foundation, fair and reasonable, and related
to roadway risk. Posted speed limits reflect a balance of the various factors specific to
the roadway. As a result, roadway safety can be improved and community concerns
about traffic speed are appropriately and legally addressed.
BASIS OF ACTION:
The proposed speed limit for the road segment discussed in this report is regulated by
section 22357(a) of the California Vehicle Code: "Whenever a local authority
determines upon the basis of an engineering and traffic survey that a speed greater
than 25 miles per hour would facilitate the orderly movement of vehicular traffic and
DATA:
would be reasonable and safe upon any street other than a state highway otherwise
subject to a prima facie limit of 25 miles per hour, the local authority may by ordinance
determine and declare a prima facie speed limit of 30, 35, 40, 45, 50, 55, or 60 miles per
hour or a maximum speed limit of 65 miles per hour, whichever is found most
appropriate to facilitate the orderly movement of traffic and is reasonable and safe. The
declared prima facie or maximum speed limit shall be effective when appropriate signs
giving notice thereof are erected upon the street and shall not thereafter be revised
except upon the basis of an engineering and traffic survey. This section does not apply
to any 25 mile per hour prima facie limit which is applicable when passing a school
building or the grounds thereof or when passing a senior center or other facility
primarily used by senior citizens."
This portion of Estrella de Mar Road has one travel lane in each direction and extends
from Alga Road on the south to 675 feet north of Beryl Way on the north. The roadway
is not striped. The road follows a curvilinear alignment with grades ranging from 1% to
6% and has a curb-to-curb width which varies between 34 feet at the very north end
and 48 feet at the very south end where a 92-foot raised, landscaped median exists.
The majority of the roadway is 40 feet wide from curb-to-curb. Intersections exist at
Dove Lane, a public street, and Feldspar Place, Feldspar Place/Beryl Way and Mercury
Place which are all private streets. Dove Lane and Beryl Way are minor-street STOP
controlled. The remaining three streets are uncontrolled.
Adjacent land use includes single-family residential, multi-family residential, open
space, a golf course, and a SDGE easement. Nearby land uses include two shopping
centers, a library, and a post office. However, the number of driveways with direct
access to Estrella de Mar does not meet the requirement to be classified as a resident
district that allows a 25 mph speed limit.
On August 30 and August 31, 2016, traffic counts were obtained on Estrella de Mar
Road to measure the two-way, 24-hour average daily traffic volume. The count data is
indicated on Table A.
TABLE A
24-HOUR TRAFFIC VOLUMES
24-Hour ADT
Date Location NB SB Total
8/30/16 North of Beryl Way 416 347 763
8/31/16 North of Alga Road 216 436 652
Staff reviewed the Police Department traffic collision reports for the two-year period
from January 1, 2015 through December 31, 2016. During that time there was one
reported traffic collision, a solo-vehicle collision where the driver drove off the road
south of Dove Lane.
As indicated on Table B, staff conducted a speed survey on Estrella de Mar Road on
August 22, 2016 to obtain data to calculate the critical speed of vehicles. The critical
speed, commonly called the 85th percentile speed, is the free flowing speed at which 85
percent of the vehicles are traveling at or below. A sample of 50 vehicles was measured
to determine the critical speed. The critical speed is an important factor required to be
considered in the evaluation of the appropriate prima facie speed to post upon a
roadway. The pace speed is the 10 mile per hour range of speeds that contain the
highest number of observed vehicles.
Survey
Date
TABLE B
SPEED SURVEY DATA
Location Direction
8/22/16 At Beryl Way/Feldspar Place NB/SB
RECOMMENDATION:
Critical Pace
Speed Speed %in
(MPH) (MPH) Pace
32 25-35 96%
Based upon the results of the Engineering and Traffic Survey, the Traffic Safety
Coordinating Committee recommends establishing a 30 mile per hour prima facie speed
limit upon Estrella de Mar Road from Alga Road to 675 feet north of Beryl Way.
NECESSARY CITY COUNCIL ACTION:
An ordinance will be required to be adopted by the City Council to establish the 30 mile
per hour prima facie speed limit upon Estrella de Mar Road from Alga Road to 675 feet
north of Beryl Way, as recommended.
Attachments:
1. Location Map
2. Engineering and Traffic Survey
LOCATION MAP
FELDSPAR
PLACE
MERCURY
PLACE
NOT TO SCALE
PROPOSED 30 MPH
SPEED ZONE
SITE
PROJECT NAME PROPOSED 30 MPH SPEED ZONE EXHIBIT
ESTRELLA DE MAR ROAD -ALGA ROAD TO 675 FEET NORTH OF BERYL WAY
PLOTTED BY: JIM GALE PLOT DATt:2/23/17 PATH:Q:\PUBLJC WORKS\TRANSP0RTA710N\TRAmc DMSION\TRAmc OPERA710NS\AUTOCAD\GALE\2017 WORK ORDERS\LOCA710N
MAPS\ESTRELLA DE MAR N-0 ALGA LOCA 710N MAP.DWG
1
CITY OF CARLSBAD
ENGINEERING AND TRAFFIC SURVEY
STREET: Estrella de Mar Road
LIMITS: Alga Road to 675 Feet north of Beryl Way
FACTORS
Direction:
A. Prevailing Speed Data: Northbound/ Southbound
Date of Speed Survey 8/22/16
Location of Speed Survey At Beryl Way/Feldspar Place
85th Percentile 32MPH
10 MPH Pace 25to 35 MPH
Percent in Pace 96%
8. Accident Histon,::
(1/01/15 through 12/31/16)
Speed-Related Accidents None
Pedestrian and/or Bicycle Accidents None
Total Accidents 1
C. Traffic Factors:
Average Daily Traffic 763-North of Beryl Way (8/30/16); 652-North of Alga Road (8/31/16)
Traffic Controls Stop sign at Alga Road; Beryl Way and Dove Lane are minor street Stop-controlled
Pedestrian/Bicycle Traffic Light
Bicycle Lanes No Striped Bicycle Lanes
On-Street Parkinq Parking Allowed on Each Side
D. Roadway Factors:
Length of Segment 0.33 Miles (1,720 Feet)
Roadway Width 34 to 48 Feet (Curb-to-Curb)
Number of Lanes One Lane Each Direction
Vertical Alignment Roadway Grades Vary from 1.0% to 6%
Horizont91 Alignment Curvilinear
Sidewalks Sidewalk on Each Side
Driveways Two Driveways
Street Lighting Street Lights on Each Side
E. Soecial Conditions: Travel lanes are separated by a raised, landscaped median just north of Alga Road.
F. Adiacent Land Uses: Sinale-Family Residential, Multi-Family Residential, Golf Course, Open Space, SDGE Easement
G. Remarks/Conditions Not Readily Apparent: Four private streets intersect the roadway, two of which are Stop-controlled on the
minor leg.
H. Traffic Engineer's Recommendation (Explanation): This speed zone satisfies the conditions of Section 627 of the California
Vehicle Code and has been prepared and evaluated in accordance with the California Manual on Uniform Traffic Control Devices,
effective November 7, 2014, with respect to design and prevailing speeds, accident records, pedestrian and bicyclist safety,
intersection and driveway spacing, and roadside and traffic conditions not readily apparent to the driver. A speed limit posting of
30 MPH is found to be aooropriate and justified.
I. Approvals:
D Recertification of e~sting speed zone pe< Sections 22357, 22358 an<~802 ofthe California Vehicle Code.
gJ Establishment of new speed zone. ,-~
J.-')__ ·3-\ 1 Approved \\... (.jl,le{.,
Doug BilsE() Date
City Traffic Engineer
CATR 2279
NOTE: Appropriate speed survey 1s attached hereto and made a part hereof.
DATE: 8/22/2016 TIME: 3:45 PM
WEATHER: Sunny & Mild
TO
CITY OF CARLSBAD
SPEED SURVEY
5:15 PM TOTAL VEHICLES:
CRITICAL SPEED:
LOCATION: Estrella de Mar Road@ Beryl Wa~/Feldspar Place VEHICLES IN PACE:
OBSERVER/RECORDER: J. Gale
NORTHBOUND
DIRECTION OF TRAVEL
MPH
65
64
63
62
61
60
59
58
57
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
40
39
38
37
36 X
35
34 X X
33 X
32 X X X X
31 X X
30 X
29
28 X X
27 X X X X X
26 X X X X
25 X X X
24
23
22
21
PACE SPEED(S):
# % }:.# % %tile % #
1 4 1 2 100
98
2 8 3 6 98 4
1 4 1 2 92
4 16 5 10 90 4
2 8 5 10 80 12
1 4 4 8 70 12
2 4 62 8
2 8 6 12 58 16
5 20 10 20 46 20
4 16 7 14 26 12
3 12 5 10 12 8
1 2 2 4
Public Works Department
Traffic and Mobility Division
1
1
3
3
2
4
5
3
2
1
50
32 MPH
96 %
25 TO 35 MPH
SOUTHBOUND
DIRECTION OF TRAVEL
MPH
65
64
63
62
61
60
59
58
57
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
40
39
38
37
36
35
X 34
33
X 32
X X X 31
X X X 30
X X 29
X X X X 28
X X X X X 27
26
X X 25
X 24
23
22
21
Estrella de Mar Speed Limit
Traffic Safety Commission
March 6, 2017
Speed Limits in California
•Voluntary compliance is a primary goal
•Drivers determine speed limit, except legally defined
roadways (e.g., residential and business districts)
•Most drivers are rational (85% of drivers)
•Speed limits are established in 5 mph increments
•Speed limit set within 5 mph of 85% speed, except…
2
City Traffic Engineer Discretion
5 MPH Reduction
•5 mph reduction is allowed if both of these
conditions are met:
•There is a condition “not readily apparent to driver”
(e.g., a relatively high collision rate)
•Speed limit is closest increment to 85th percentile
speed
3
Location
Map
4
Engineering &
Traffic Survey
5
E&T Survey: Factors
6
A. Prevailing Speed Data:
Date of Speed Survey
Location of Speed Survey
85th Percentile
10 MPH Pace
Percent in Pace
B. Accident History:
(1/01/15 through 12/31/16)
FACTO~S
Direction:
Northbound/ Southbound
8/22/16
At Beryl Way/Feldspar Place
32MPH
25 to 35 MPH
96%
Speed-Related Accidents None
Pedestrian and/or Bicycle Accidents None
Total Accidents 1
C. Traffic Factors:
Average Daily Traffic
Traffic Controls
Pedestrian/Bicycle Traffic
Bicycle Lanes
On-Street Parkin
763 -North of Beryl Way (8/30/16); 652 -North of Alga Road (8/31/16)
Stop sign at Alga Road; Beryl Way and Dove Lane are minor street Stop-controlled
Light
No Striped Bicycle Lanes
Parking Allowed ·on Each Side
Staff Recommendation
•Recommend for approval of 30 mph prima facia
speed limit on Estrella de Mar Road between Alga
Road and 675 feet north of Beryl Way
7