HomeMy WebLinkAbout2010-06-07; Traffic Safety Commission; ; Establish a prima facie speed limit upon Greenhaven Drive from Muirfields Drive to El Fuerte StreetCITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
COMMISSION MEETING OF: June 7, 2010 ITEM NO. 6B
LOCATION:
INITIATED BY:
Greenhaven Drive, from Muirfields Drive to El Fuerte Street
Gordon Cromwell, Carlsbad, California
REQUESTED ACTION: Establish a prima facie speed limit upon Greenhaven Drive from
Muirfields Drive to El Fuerte Street.
BACKGROUND:
Mr. Cromwell sent an email to staff asking that a study be conducted to determine if a
prima facie speed limit should be conducted on the referred segment of Greenhaven
Drive due to concerns with the speed of vehicles.
As shown on Exhibit I, Greenhaven Drive is a local street that intersects the El Fuerte
Street signalized intersection in a "T" intersection configuration and traverses north-
westerly to its terminus at Gardenhouse Road.
SETTING SPEED LIMITS:
Effective July I, 2009, Caltrans Division Chief Robert Copp signed the Policy Directive
to establish the procedure for setting speed limits in California. The changes for setting
speed limits are included in the California Manual on Uniform Traffic Control Devices
(CA MUTCD) pursuant to authority granted to Caltrans in Section 21400 and 21401 of
the California Vehicle Code (CVC).
Caltrans recognizes that the setting of speed limits can be controversial. However, if
speed limits are established arbitrarily low, the majority of drivers would be violators of
the speed limit, public confidence would be low, and roadway users ( drivers) would not
respect the traffic control device (speed limit sign).
The referenced directive clarifies procedures for setting speed limits. Caltrans has
incorporated two new standards into the CA MUTCD to help set speed limits in
California that are uniform, rational, enforceable by the police, and are supported by the
judicial system. Requirements of the new standards as established by Caltrans are:
• The speed limit shall be established at the nearest 5 mph increment of the
85th percentile.
• If the 5 mph reduction is applied, the Engineering and Traffic Survey shall
document in writing the conditions and justification for the reduced speed
limit and be approved by a registered Civil or Traffic Engineer.
The 85 th percentile speed, often referred to as the critical speed, is the speed which 85%
of the drivers are traveling at or below.
CITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
COMMISSION MEETING OF:
( continued)
June 7, 2010 ITEM NO. 6B
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. Unfortunately, good judgment is not used by all
operators of a motor vehicle.
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 even though
their capabilities and limitations of the vehicle operators vary greatly. 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.
Many factors influence the speed at which drivers operate their vehicle. Human factors
include age, gender, state of mind (attitude), attentiveness, and concerns about law
enforcement or being involved in a collision. There are situational factors that can
influence speed such as weather, condition of the vehicle, roadway conditions, speed
limits or being in a hurry or impaired.
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.
In the City of Carlsbad, the predominant practice for managing speed is by legally
establishing a prima facie speed limit according to Caltrans criteria 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
CITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
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June 7, 2010 ITEMNO.6B
have been set on a reasonable basis, the enforcement efforts of the Carlsbad Police
Department 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 and the latest revision thereof
is used to set speed limits in California. 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 Engineering and Traffic 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 most persuasive arguments to consider when setting a realistic, or
rational, speed limit are:
I . Critical speed (85 th percentile speed)
2. Collision history
3. Conditions that may not be readily apparent to the driver
4. Type and amount of roadside development
5. Design speed of the roadway
6. Horizontal and vertical alignment of the roadway
7. Pedestrians and bicyclists
The premise implied in sfeed zoning is that the majority of drivers are operating their
vehicles at or near the 851 percentile speed. Drivers that operate their vehicle at speeds
higher than the 85 th percentile speed should be the focus of the police as excessive speed
is often a factor in a vehicle collision.
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 85 th 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.
A comprehensive review of the collision history on a roadway also 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
CITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
COMMISSION MEETING OF:
( continued)
June 7, 2010 ITEM NO. 6B
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. From national statistics and studies, it is known that high mileage
drivers, young drivers, those driving new cars, and those driving for business purposes
tend to drive faster than average and/or exceed the speed limit.
Traffic engineers recognize that 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 tum, is
considered when establishing a prima facie speed limit.
A number of factors may be considered when establishing a prima facie speed limit.
The CA 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.
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
CITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
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June 7, 2010 ITEMNO.6B
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 and at which they feel safe regardless of the posted
speed limit.
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."
DATA:
Greenhaven Drive is unclassified in the Circulation Element of the General Plan and
functions as a collector road. It is a two-lane road in the Bressi Ranch neighborhood
located in central Carlsbad. The portion of Greenhaven Drive between Gardenhouse
Road and Muirfields Drive is notably different in physical characteristics (residential,
parking allowed on both sides of the street, traffic calming features at irregular intervals
on either side of the street, no centerline striping) than the easterly portion of Greenhaven
CITY OF CARLSBAD
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COMMISSION MEETING OF:
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June 7, 2010 ITEMNO.6B
Drive between Muirfields Drive and El Fuerte Street and will be not be analyzed for this
staff report.
The subject segment of Greenhaven Drive from Muirfields Drive to El Fuerte Street
features concrete curb and gutter, non-contiguous sidewalk, bicycle lanes, and street
lights on both sides of the roadway. The subject road has a length of 0.43 miles and a
curb to curb width between 30 and 52 feet.
Parking is not allowed on either side of the subject roadway and a painted centerline
stripe separates traffic in each direction. A YIELD-controlled traffic circle is provided on
Greenhaven Drive where it intersects Muirfields Drive. The intersection of Greenhaven
Drive and El Fuerte Street is controlled by a traffic signal. Greenhaven Drive is
uncontrolled at the other four intersections between Muirfields Drive and El Fuerte Street
with the side streets being STOP controlled. Greenhaven Drive has a curvilinear
alignment and the vertical grades on the road vary from 3.0% to 9.3%.
Based upon traffic counts obtained March 30, 2010 on Greenhaven Drive, the two-way
traffic volume is low and was measured at between 789 and 1,420 vehicles per day. The
directional distribution of traffic volumes on Greenhaven Drive at the indicated locations
is provided in Table A.
DATE
3/30/10
3/30/10
TABLE A
24-HOUR TRAFFIC VOLUMES
GREENHA VEN DRIVE
LOCATION EB
w/o El Fuerte Street 739
w/o Live Oaks Drive 412
24-HOURADT
. WB TOTAL
681 1,420
377 789
There have been no reported collisions on Greenhaven Drive for the two-year period ending
February 28, 2010.
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 provides guidance when a
speed limit is to be posted. It states that the speed limit should be established at the
nearest 5 mph increment of the 85th percentile speed. However, in matching existing
conditions with the traffic safety needs of the community, engineering judgment may be
used for a further reduction of 5 mph. The additional 5 mph reduction requires
significant documentation as to the reason.
,....,
CITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
COMMISSION MEETING OF:
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June 7, 2010 ITEM NO. 6B
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 (I) to (3), inclusive, of subdivision (b) may
consider all of the following:
(I) 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.
Staff completed the required Engineering and Traffic Survey (attached) for Greenhaven
Drive that is the basis for the recommended prima facie speed limit. The speed survey
results contained within the Engineering and Traffic Survey are summarized in Table B.
One speed survey was performed on March 25, 2010 in a location where prevailing
speeds are representative of driver behavior in the proposed speed zone.
TABLEB
SPEED SURVEY DAT A FOR GREENHA VEN DRIVE
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.
r ,......_
CITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
COMMISSION MEETING OF:
( continued)
June 7, 2010 ITEM NO. 6B
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 subject Engineering and Traffic Survey considered 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 40 mile per hour prima facie speed
limit upon Greenhaven Drive from the intersection at Muirfields Drive to the intersection
at El Fuerte Street.
NECESSARY CITY COUNCIL ACTION:
An ordinance will be required to be adopted by the City Council to establish the 40 mile
per hour prima facie speed limit upon Greenhaven Drive, as recommended.
Jim Murray
From:
Sent:
To:
Subject:
Dear Mr. Murray,
r
gordon cromwell [gordoncromwell@hotmail.com]
Monday, June 08, 2009 3:56 PM
Jim Murray
Greenhaven Drive
-
As per your instructions from our phone conversation on June 8th, I am sending you this email to request
a traffic study of of Greenhaven Drive between El Fuerte and Muirlands in the Bressi Ranch neighborhood.
I am requesting this specifically to determine the feasibility of establishing all-way stops at the
intersections of Live Oak, Plumeria, and Huntington Drive, as well as establishing a posted speed limit on
Greenhaven Drive.
Thank you for your consideration in this matter, I look forward to your reply.
Sincerely,
Gordon Cromwell e: gordoncromwell@hotmail.com h: (760)724-1501 c: (858)442-1459
Hotmail® has ever-growing storage! Don't worry about storage limits. Check it out,
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LOCATION MAP
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PROPOSED SPEED ZONE FOR
GREENHAVEN DRIVE
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NOT TO SCALE
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CITY OF CARLSBAD
ENGINEERING AND TRAFFIC SURVEY
STREET: Greenhaven Drive
LIMITS: Muirfields Drive to El Fuerte Street
A. Prevailing Speed Data:
Date of Speed Survey
Location of Speed Survey
85th Percentile
10 MPH Pace
Percent in Pace
Posted Speed Limit
B. Midblock Accident History:
(3/01/08 through 2/28/10)
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 Parkinq
D. Roadway Factors:
Circulation Element Street Classification
Length of Segment
Roadway Width
Number of Lanes
Vertical Alignment
Horizontal Alignment
Sidewalks
Driveways
Street Liahtina
FACTORS
Direction: Eastbound/Westbound
3/25/10
175 Feet east of Plumeria Drive
40 MPH
32 to 42 MPH
83%
No Posted Soeed Limit
None
None
None
1. 71 (2007 State Rate for Same Type of Roadway)
1,420 -w/o El Fuerte Street (3/30/1 O); 789 -w/o Live Oaks Drive (3/30/10)
Yield Sign Control & Traffic Circle at Muirfields Dr.: Traffic Signal control at El Fuerte St.
Light
Bicycle Lane on Each Side
Parking Prohibited on Both Sides
Unclassified
043Mi.
Roadway Width varies from 30 Feet to 52 Feet (Curb-to-Curb)
One Lane Each Direction
Roadway Grades Vary from 3% to 9.3%
Curvilinear
Sidewalk on Each Side
No Driveways
Street Liahts on Both Sides
E. Special Conditions: This portion of Greenhaven Drive functions as a collector street. Travel lanes are separated by a double-
yellow centerline. Choke points where road is reduced to 25 feet approaching Huntington Drive and 21 feet approaching Plumeria
Drive.
F. Adiacent Land Uses: Single-Family Residential
G. Remarks/Conditions Not Readily Apparent: Between Muirtields Drive and El Fuerte Street, three public streets intersect the
roadway on the north side. On the south side, one private street and two public streets intersect the roadway. A playground in the
neiahborhood on the south side of the roadwav mav result in children crossina the street.
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 Caltrans Traffic Operations Policy Directive 09-04
Effective July 1, 2009 and 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
annarent to the driver. A soeed limit oostino of 40 MPH is found to be annrooriate and iustified.
I. Approvals:
□ Recertification of existing sP,eed zone per Sections 22357, 22358 and40802 of the California Vehicle Code.
ll"Establishment of new speed zone.
Approved k?.,1,.y,-;--I, ~<h f· +/ /'Z-/;~
City Engineer . • Date
CARCE 28515 Reoistration exoires 3/31/12
NOTE: Appropriate speed survey(s) Is /are attached hereto and made a part hereof.
,......, _____________ ...... ·---------------·----------------
DATE: 03/25/10 TIME: 9:35 AM TO
CITY OF CARLSBAD
SPEED SURVEY
1:45 PM TOTAL VEHICLES:
WEATHER: Clear & Warm CRITICAL SPEED:
LOCATION: Greenhaven Drive ~175' e/o Plumeria Drive VEHICLES IN PACE:
OBSERVER/RECORDER: .cM::.:·..:.R:.:ec.:h:.:fe:::ld:.:.t ____ _ PACE SPEED(S):
NONE
POSTED SPEED LIMIT
WESTBOUND
DIRECTION OF TRAVEL
MPH # % I:# % %tile % #
65
64
63
62
61
60
59
58
57
56
55
54
53
52
51
50
49
48
47
46
45
44
43 X
42 X
41 X X
40 X
39 X X X X
38 X X X X
37 X X X
36 X X X X
35 X X X X X X
34 X X X X X X
33 X X X X X X X
32 X X X X X
31 X
30 X X
29 X X
28 X
27
26
25
24
23
22
21
1 1 100 2 1
1 2 4 4 99 6 3
1 2 3 3 95 4 2
2 4 6 6 92 8 4
1 2 6 6 86 10 5
4 8 7 7 80 6 3
4 8 9 9 73 10 5 3 6 5 5 64 4 2
4 8 9 9 59 10 5
6 12 11 11 50 10 5
6 12 11 11 39 10 5 7 14 11 11 28 8 4
5 10 8 8 17 6 3
1 2 1 1 9
2 4 4 4 8 4 2
2 4 3 3 4 2 1
1 2 1 1 1
Transportation Department
Traffic Division
100
40 MPH -----~-----
83 % -----------
32 TO 42 MPH ----
EASTBOUND
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
X 44
X X X 43
X X 42
X X X X 41
X X X X X 40
X X X 39
X X X X X 38
X X 37
X X X X X 36
X X X X X 35
X X X X X 34
X X X X 33
X X X 32
31
X X 30
X 29
28
27
26
25
24
23
22
21