HomeMy WebLinkAbout2008-10-06; Traffic Safety Commission; ; Establish a prima facie speed limit upon Corte de la Vista from the El Fuerte Street/ Alicante Road intersection to its easterly terminus( (
CITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
COMMISSION MEETING OF: October 6, 2008 ITEMNO. 6A
LOCATION: Corte de la Vista, El Fuerte Street/ Alicante Road intersection to its
easterly terminus
INITIATED BY: Karen Starns, 2910 Avenida Valera, Carlsbad, California 92009
REQUESTED ACTION: Establish a prima facie speed limit upon Corte de la Vista from the
El Fuerte Street/ Alicante Road intersection to its easterly terminus.
BACKGROUND:
As shown on Exhibit 1, Corte de la Vista is a local street that intersects the El Fuerte
Street/ Alicante Road intersection in a "T" intersection configuration and traverses south-
easterly to its terminus at Sondra Court. A local resident has expressed concern with the
speed of vehicles using Corte de la Vista and requested that a prima facie speed limit be
established.
SETTING SPEED LIMITS:
Optimal mobility is enhanced and overall traffic flow improved when drivers are
operating their vehicles at a speed that is reasonable, comfortable, convenient, and safe
under the existing conditions. It is generally acknowledged that the control of speed can
be a significant factor in influencing and improving roadway safety by reducing the
number of collisions. In fact, the premise of CVC section 22350, Basic Speed Law, is
that no person shall drive upon a road at a speed greater than is reasonable and prudent
taking into account weather, visibility, and traffic on the road and in no event at a speed
that endangers the safety of others.
Driver behavior is an extension of social attitudes and most drivers operate their vehicles
in a reasonable manner. This is demonstrated by their good driving records.
Therefore, traffic laws established on the basis of the behavior of the reasonable and
prudent motorist are found to be the most successful. As a result, speed limits that are
considered credible and enforceable will help enhance traffic safety and the operating
efficiency on the roadway and achieve driver compliance.
Roads in Carlsbad are designed in accordance with engineering standards to satisfy the
goals of having a safe roadway, provide mobility, offer mode choices, and to enhance
efficient traffic flow. One way that these goals are achieved is by establishing proper and
reasonable speed limits that can be enforced. Speed limits that are reasonable can help to
achieve voluntary compliance by the majority of drivers without need for the presence of
a police officer. Laws and/or the establishment of speed zones that arbitrarily restrict
travel by the majority of motorists can lead to wholesale violations of the posted speed
limit. For a speed limit to be considered effective, drivers must believe that the posted
speed limit is safe, properly established, and legally enforceable.
( (
CITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
COMMISSION MEETING OF: October 6, 2008
( continued)
ITEMNO. 6A
In the City of Carlsbad, the predominant practice for managing speed is by legally
establishing a prima facie speed limit and then posting the speed limit upon the road with
regulatory signs. A prima facie speed limit recognizes that conditions change throughout
the day and there is no one safe speed for all the conditions that may be present upon the
roadway. Police enforcement is used to target the most egregious violators of the speed
limit. 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. When law enforcement officers
and the courts have confidence that speed limits have been set on a reasonable basis, their
enforcement efforts are more effective.
Nationally recognized vetted practices and guidance per standards and procedures in the
Federal Highway Administration's national Manual on Uniform Traffic Control Devices
2003 Edition are considered when setting speed limits. In California, this manual is titled
the California Manual on Uniform Traffic Control Devices. The most common method of
establishing speed limits incorporates traffic engineering principles and other factors,
such as using the results of a speed survey, into the Traffic and Engineering Survey.
Prima facie speed limits are established by law when the City Council adopts an
ordinance and the speed limit is posted on the roadway to indicate the maximum
reasonable speed for a driver to operate a vehicle under ideal conditions in off-peak free
flowing conditions. Among many factors, the three most persuasive arguments to
consider when setting a realistic, or rational, speed limit are:
1. Critical speed (85 th percentile speed)
2. Collision history
3. Conditions that may not be readily apparent to the driver
The premise implied in speed zoning is that the majority of drivers are operating their
vehicles at or near the 85th percentile speed. Drivers that operate their vehicle at speeds
higher than the 85th percentile speed should be the focus of the police. An important
speed zoning concept is that the disparity in speed between vehicles on the road is
reduced when prima facie speed limits are established at or near the 85th percentile speed
and, as a result, safety is enhanced. In addition, a speed limit that is established based
upon the 85th percentile speed will increase driver respect for the speed limit sign.
Only those regulatory or warning signs that have the respect of the roadway user will
have a positive effect to control driver behavior traffic.
( (
CITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
COMMISSION MEETING OF: October 6, 2008
( continued)
ITEMNO. 6A
A comprehensive review of the collision history on a roadway is an 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.
A number of collisions above the expected or normal threshold based upon Caltrans
collision rates may be an indicator of a potential for reducing collisions. 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 the speed they chose to
drive.
The installation of a speed limit sign will not automatically decrease accident rates nor
increase roadway safety. Speed limits should not be lowered for conditions that are
readily apparent to the driver and the speed limit signs are not used as intersection, curve
or hazard warning devices. For the unusual conditions or conditions not readily apparent
to motor vehicle operators, appropriate warning signs are installed.
Design factors, including the geometric elements of the road, sight distance, or other
factors such as adjacent land uses, parking, or pedestrian activity, may have a significant
impact on the free flowing speed chosen by drivers. This driver chosen speed, in turn, is
considered when establishing a prima. facie speed limit.
A number of factors may be considered when establishing a prima facie speed limit.
The 2003 MUTCD lists such factors as:
A. Road characteristics, shoulder condition, grade, alignment, and stopping sight
distance;
B. The pace speed;
C. Roadside development and activity; and
D. Reported crash experience for at least a 12-month period.
Other factors are included, as appropriate, in the Engineering and Traffic Survey that
becomes the basis for establishing the prima facie speed limit. Among the requirements
to be considered are residential density and pedestrian and bicycle safety. Other factors
include superelevations, profile conditions, intersection spacing and offsets, commercial
driveways, and pedestrians in the roadway where sidewalks do not exist.
( (
CITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
COMMISSION MEETING OF: October 6, 2008
( continued)
ITEMNO. 6A
Basic speed law as stipulated in the California Vehicle Code requires drivers to operate
their vehicle at a speed that takes into account all roadway factors, environmental
elements, adjacent land uses, and other traffic on the road. These are, in general, all
readily apparent factors to the driver. Warning signs placed on the roadway can alert
drivers to the presence of an unseen or unanticipated condition. As a result, drivers can
operate their vehicle in a reasonable and prudent manner by adjusting speed for the
condition that may be encountered.
In summary, through the use of engineering, educational, and enforcement techniques,
the management of vehicle speed is conducted. Voluntary public compliance with the
posted speed limit is the goal when determining a realistic prima facie speed limit to post
on a roadway. The. realistic speed limit takes into consideration the normally competent
and careful actions of a reasonable driver and provides for the regulation of unreasonable
behavior by a few individuals. A posted speed limit should be readily accepted by drivers,
be fair and reasonable, be related to risk on the roadway, be determined by the majority of
drivers, and one that has a factual foundation. 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 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."
(
CITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
COMMISSION MEETING OF: October 6, 2008
( continued)
DATA:
ITEMNO. 6A
Corte de la Vista is unclassified in the Circulation Element of the General Plan and is a
two-lane road that has a curb to curb width of 40 feet. Concrete curb and gutter and
sidewalk have been constructed on both sides of the roadway with street lights installed
on the north side only. Due to the residential units located south of Corte de la Vista
having been built below the street level, metal guardrail has been installed along the
entire south side of Corte de la Vista. The road has a length of 0.40 miles.
Parking is allowed on both sides of Corte de la Vista and no centerline stripe has been
installed. Five streets, one of which is a public street, each intersect Corte de la Vista in a
"T" intersection configuration. Stop sign control is provided on Corte de la Vista where
it intersects El Fuerte Street/ Alicante Road. At this intersection, there is a street name
change with Alicante Road continuing westerly and El Fuerte Street continuing easterly.
Corte de la Vista has a generally straight horizontal alignment. Vertical grades on the
road vary from 1.0% to 5.8%.
Based upon traffic counts obtained September 3, 2008 on Corte de la Vista, the two-way
traffic volume is low and was measured at 1,057 vehicles per day. The directional
distribution of traffic volumes on Corte de la Vista is provided in Table A.
DATE
9/03/08
TABLE A
24-HOUR TRAFFIC VOLUMES
CORTE DE LA VISTA
LOCATION E/B
55' e/o El Fuerte Street/Alicante 507
Road intersection
24-HQURADT
W/B TOTAL
220 1,057
There have been no reported collisions on Corte de la Vista for the two-year period ending
July 31, 2008. The absence of a collision history supports the recommended 35 mile per
hour prima facie speed limit.
( (
CITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
COMMISSION MEETING OF: October 6, 2008 ITEMNO. 6A
( continued)
Critical speeds, also known as the 85th percentile speeds, have been determined
throughout the United States to generally conform to a safe and reasonable speed limit.
The California Manual on Uniform Traffic Control Devices (FHWA's MUTCD 2003
Revision 1, as amended for use in California) provides guidance when a speed limit is to
be posted. It states that "the speed limit should be established at the nearest 10 km/h
(5 mph) increment to the 85th percentile speed. However, in matching existing conditions
with the traffic safety needs of the community, engineering judgment may indicate the
need for a further reduction of 10 km/h ( 5 mph)."
California Vehicle Code section 627 defines the term "Engineering and Traffic Survey"
and lists its requirements, as follows:
627. (a) "Engineering and traffic survey," as used in this code, means a survey of
highway and traffic conditions in accordance with methods determined by the
Department of Transportation for use by state and local authorities.
(b) An engineering and traffic survey shall include, among other requirements
deemed necessary by the department, consideration of all of the following:
( 1) Prevailing speeds as determined by traffic engineering measurements.
(2) Accident reports.
(3) Highway, traffic, and roadside conditions not readily apparent to the driver.
( c) When conducting an engineering and traffic survey, local authorities, in
addition to the factors set forth in paragraphs (1) to (3), inclusive, of subdivision (b) may
consider all of the following:
(l)Residential density, if any of the following conditions exist on the particular
portion of highway and the property contiguous thereto, other than a business district;
(A) Upon one side of the highway, within a distance of a quarter of a mile, the
contiguous property fronting thereon is occupied by 13 or more separate dwelling houses
or business structures.
(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.
( c) 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).
(2) Pedestrian and bicyclist safety.
(
CITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
COMMISSION MEETING OF: October 6, 2008
( continued)
ITEMNO. 6A
Staff completed the Engineering and Traffic Survey ( attached) for Corte de la Vista. The
speed survey results contained within the Engineering and Traffic Survey are summarized
in Table B. One speed survey was performed on July 16, 2008 in a location where
prevailing speeds are representative of driver behavior in the proposed speed zone.
TABLEB
SPEED SURVEY DATA FOR CORTE DE LA VISTA
Sun:ey
Date
7/16/08 225' w/o Avenida Valera EB/WB 35 27-37
%in
Pace
85
The pace speed is the 10 mile per hour range of speeds that contain the highest number of
observed vehicles. Generally, the critical speed is located in the upper range of the pace
speed.
Sections 22357 and 22358 of the California Vehicle Code authorize local authorities to
establish a prima facie speed limit on the basis of the results of an Engineering and
Traffic Survey. The Engineering and Traffic Survey considers such factors as the number
of collisions that have occurred on the road segment, roadway features, adjacent land
uses, driveway locations, traffic volumes, pedestrian volumes, critical speed, horizontal
and vertical alignment, stopping sight distance, and conditions that may not be readily
apparent to the driver.
RECOMMENDATION:
Based upon the results of the Engineering and Traffic Survey, the Traffic Safety
Coordinating Committee recommends establishing a 35 mile per hour prima facie speed
limit upon Corte de la Vista from the El Fuerte Street/ Alicante Road intersection to its
easterly terminus.
NECESSARY CITY COUNCIL ACTION:
An ordinance will be required to be adopted by the City Council to establish the 3 5 mile
per hour prima facie speed limit upon Corte de la Vista, as recommended.
(
LOCATION MAP
~ERTEST. ------..... ......___
AL~...-..
NOT TO SCALE
PROJECT NAME
PROPOSED
SPEED ZONE
PROPOSED SPEED ZONE
CORTE DE LA VISTA
DRAKN BY: SCOTT EVANS, CARLSBAD ENGINEERING DEPT. 7/Jl/08 C:\7RAffiC\SPEED ZONES\SPEED ZONE-CORTE DE LA YfSTA.DWG
SONDRA CT.
EXHIBIT
1
CITY OF CARLSBAD (
ENGINEERING AND TRAFFIC SURVEY
STREET: Corte de la Vista
LIMITS: Alicante Road/El Fuerte Street intersection to Easterly Terminus
A. Prevailing Speed Data:
Date of Speed Survey
Location of Speed Survey
85th Percentile
10 MPH Pace
Percent in Pace
Posted S • eed Limit
B. Midblock Accident History:
(8/01/06 through 7/31/08)
Speed-Related Accidents
Total Accidents
Accidents/Million Vehicle Miles (MVM)
California Statewide Accidents/MVM
C. Traffic Factors:
Average Daily Traffic
Traffic Controls
Pedestrian/Bicycle Traffic
Bicycle Lanes
On-Street Parkin
D. Roadway Factors:
Circulation Element Street Classification
Length of Segment
Roadway Width
Number of Lanes
Vertical Alignment
Horizontal Alignment
Sidewalks
Driveways
Street Li htin
Direction: Eastbound/Westbound
7/16/08
225 Feet w/o Avenida Valera
35 MPH
27 to 37 MPH
85%
No Posted S eed Limit
None
None
None
1.81 (2006 State Rate for Same Type of Roadway)
1,057 -e/o Alicante Road/El Fuerte Street intersection (9/03/08)
Stop Sign Control at Alicante Road/El Fuerte Street intersection
Light
No Designated Bicycle Lanes Have Been Striped on the Roadway
Parking Allowed on Both Sides
Unclassified
0.40Mi.
40 Feet (Curb-to-Curb)
One Lane Each Direction
Roadway Grades Vary from 1 % to 5.8%
Relatively Straight
Sidewalk on Each Side
No Driveways
Street Li hts on North Side Onl
E. Special Conditions: No centerline striping. Guardrail on entire south side.
F. Adjacent Land Uses: Single-Family Residential
G. Remarks/Conditions Not Readily Apparent: Four private streets and one public street intersect the roadway on the north side
and one private street intersects the roadway on the south side.
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
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 35 MPH is found to be appropriate
and ·ustified.
NOTE: Appropriate speed survey(s) is /are attached hereto and made a part hereof.
DATE: 07/16/08 TIME: 8:50 AM TO
WEATHER: Clear & Mild
CITY OF CARLSBAD
SPEED SURVEY
11:15AM TOTALVEHICLES:
CRITICAL SPEED: ---------------
LOCATION: Corte de la Vista ~225' w/o Avenida Valera VEHICLES IN .PACE:
OBSERVER/RECORDER: M. Rehfeldt ---------PACE SPEED(S):
None
POSTED SPEED LIMIT
EASTBOUND
DIRECTION OF TRAVEL
MPH # % E # % %tile % #
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 X X
36 X X X X
35 X X X X
34 X X X X
33 X X X
32 X X X
31 X X X X
30 X X X X X
29 X X X X X X
28 X X X X X
27 X X X X X
26 X
25 X X X
24 X
23
22
21
1 1 100 2 1
2 4 4 4 99 4 2
4 8 7 7 95 6 3
4 8 7 7 88 6 3
4 8 10 10 81 12 6
3 6 9 9 71 12 6
3 6 8 8 62 10 5
4 8 8 8 54 8 4
5 10 7 7 46 4 2
6 12 12 12 39 12 6
5 10 8 8 27 6 3
5 10 9 9 19 8 4
1 2 3 3 10 4 2
3 6 5 5 7 4 2
1 2 2 2 2 2 1
Engineering Department
Transportation Division
100
35 MPH -----------
85 % -----------
27 TO 37 MPH
WESTBOUND
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
X 38
X X 37
X X X 36
X X X 35
X X X X X X 34
X X X X X X 33
X X X X X 32
X X X X 31
X X 30
X X X X X X 29
X X X 28
X X X X 27
X X 26
X X 25
X 24
23
22
21