HomeMy WebLinkAbout2006-12-04; Traffic Safety Commission; ; Establish a prima facie speed limit upon Melrose Drive from Palomar Airport Road to the north city limit( (
CITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
COMMISSION MEETING OF: December 4, 2006
LOCATION: Melrose Drive, Palomar Airport Road to the north city limit
INITIATED BY: Deputy City Engineer, Transportation Division
ITEMNO.6A
REQUESTED ACTION: Establish a prima facie speed limit upon Melrose Drive from
Palomar Airport Road to the north city limit.
BACKGROUND:
Construction of Melrose Drive from Palomar Airport Road to the north city limit by
private developers was completed and opened to traffic on August 16, 2006. At this time,
no prima facie speed limit has been established on the subject segment of Melrose Drive.
SETTING SPEED LIMITS:
Optimal mobility is enhanced and overall traffic flow improved when drivers are
operating their vehicles at a speed that is reasonable and safe. 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. Most drivers
operate vehicles in a reasonable manner. Traffic laws established on the basis of the
behavior of the reasonable and prudent motorist are found to be the most successful.
Roads in Carlsbad are designed in accordance with engineering standards to satisfy the
goals of a safe roadway and to enhance efficient traffic flow. One way to achieve the
goals is to establish 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 moto1ists can lead to wholesale
violations of the posted speed limit.
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.
( (
CITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
COMMISSION MEETING OF: December 4, 2006
(continued)
ITEMNO. 6A
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 (85th percentile speed)
2. Collision history
3. Conditions that may not be readily apparent to the driver
The premise implied in SR_eed zoning is that the majority of drivers are operating their
vehicles at or near the 85 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. Also, a speed limit that is established based upon the
85th percentile speed will increase driver respect for the speed limit sign. Only those signs
that have the respect of the roadway user will have a positive effect to control traffic.
A review of the collision history on a roadway is an important element in the process to
establish a speed limit. The review will reveal if there is a high incidence of speed-related
collisions on the road at specific locations. Absent a significant collision history
attributed to speed, it can 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 does not automatically decrease accident rates nor
increase roadway safety. Speed limits should not be lowered for conditions that are
readily apparent 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 drivers,
appropriate warning signs are installed.
Design factors such as the geometric elements of the road, sight distance, or other factors
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.
(
CITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
COMMISSION MEETING OF: December 4, 2006
(continued)
ITEMNO. 6A
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 sight distance;
B. The pace speed;
C. Roadside development and activity; and
D. Reported crash experience for at least a 12-month period.
As stated, basic speed law 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. 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
establish. 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.
DATA:
Melrose Drive is designated as a prime arterial on the Circulation Element of the General
Plan. The road segment north of Palomar Airport Road was opened to public travel on
August 16, 2006 and has a daily two-way traffic volume of about 21,000 vehicles based
upon two traffic counts taken on November 1, 2006 and as shown on Table A. The ADT
volumes on a prime arterial are expected to be in excess of 40,000 vehicles.
Lionshead A venue intersects Melrose Drive northerly of Palomar Airport Road
(see Exhibit 1). As the industrial park continues to develop, Lionshead Avenue at
Melrose Drive will generate more traffic through the signalized intersection.
Melrose Drive has the minimum standard prime arterial cross-section of three traffic
lanes in each direction separated by a raised landscaped median. Immediately south of
Lionshead A venue, a fourth northbound lane is provided that serves as a right-tum only
lane to eastbound Lionshead A venue. Southbound Melrose Drive at the Palomar Airport
Road intersection is striped temporarily with two southbound lanes and two right-turn
only lanes until future widening of Melrose Drive south of Palomar Airport Road is
completed. At that time, the two through lanes will change to three southbound lanes with
one right-turn only lane.
DATE
11/01/06
11/01/06
TABLE A
24-HOUR TRAFFIC VOLUMES
PALOMAR AIRPORT ROAD
s/o Lionshead A venue
n/o Lionshead Avenue 9,954 11,056 21,010
(
CITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
COMMISSION MEETING OF: December 4, 2006 ITEMNO. 6A
(continued)
The segment of Melrose Drive from Palomar Airport Road to Carlsbad's north city limit
is 0.34 miles in length. Roadway tangent segments join horizontal curves having a
centerline radius of either 2,000 feet or 2,200 feet. The horizontal alignment of
Melrose Drive was designed to connect the existing Palomar Airp01t Road/Melrose Drive
intersection with the terminus point of Melrose Drive located in Vista. The Carlsbad
portion of Melrose Drive was constructed with city standard curb and gutter, sidewalks,
and street lights on both sides.
Staff conducted a speed survey on Melrose Drive on November 2, 2006 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 100 vehicles was measured to calculate the critical
speed. The critical speed is an important factor required to be considered in the
evaluation to establish the appropriate prima facie speed to post upon a roadway.
The 85th percentile speed has been determined throughout the United States to generally
conform to a safe and reasonable speed limit. The California Manual on Uniform Traffic
Control Devices (FHW A's MUTCD 2003 Revision. I, 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) incre~ent 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:
(1) 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: December 4, 2006
( continued)
ITEMNO. 6A
Staff completed the Engineering and Traffic Survey (attached) for Melrose Drive from
Palomar Airport Road to the north city limit. Results of the speed survey, contained
within the Engineering and Traffic Survey that was conducted on Melrose Drive,
are summarized in Table B.
TABLEB
SPEED SURVEY DATA FOR MELROSE 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.
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.
There have been no reported collisions on the subject segment of Melrose Drive since it
opened to traffic on August 16, 2006.
Based upon the results of an Engineering and Traffic Survey, Melrose Drive south of
Palomar Airport Road has a posted speed limit of 55 miles per hour. Melrose Drive north
of the subject segment in the City of Vista has a posted speed -limit of 50 miles per hour
that was established when the road terminated at the south city limit of Vista. The Vista
traffic engineer has indicated that a re-evaluation of the speed limit upon Melrose Drive
in Vista will be necessary because of the road connection between Palomar Airport Road
and Vista now having traffic.
RECOMMENDATION:
Upon review of the results of the Engineering and Traffic Survey, the Traffic Safety
Coordinating Committee recommends establishing a 55 mile per hour prima facie speed
limit upon Melrose Drive from Palomar Airport Road to the north city limit.
NECESSARY CITY COUNCIL ACTION:
An ordinance will be required to be adopted by the City Council to establish the 55 mile
per hour prima facie speed limit upon Melrose Drive, as recommended.
________ ..._ __________ ......._( -----------.. LOCATION
PROPOSED
SPEED ZONE
MAP
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CITY OF VISTA
CITY OF CARLSBAD
LEGEND: I
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NOT TO SCALE
PROJECT· NAME
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PROPOSED SPEED ZONE
MELROSE DRIVE
PALOMAR AIRPORT ROAD TO NORTH CITY LIMIT
DRAW BY: SCOTT [VANS, CARLSBAD £NG/NffRING D[PT. 9/1/06 C:\TRAFRC\SPffD ZON[\SPffD ZON£-M£LROS[ DR/\1£ NOR1H.DWG
EXHIBIT
1
; CITY OF CARLSBAD • I
E~~INEERING AND TRAFFIC SUh vEY
STREET: Melrose Drive
LIMITS: North City Limit to Palomar Airport Road
A. Prevailing Speed Data:
Date of Speed Survey
Location of Speed Survey
85th Percentile
10 MPH Pace
Percent in Pace
Posted S eed Limit
Direction: Northbound/Southbound
11/02/06
450 Feet s/o Lionshead Avenue
54MPH
44 to 54 MPH
72%
No Posted S eed Limit
B. Midblock Accident History:
(8/16/06 to Present)
Speed-Related Accidents
Total Accidents
None
Accidents/Million Vehicle Miles (MVM)
California Statewide Accidents/MVM
None (road opened 8/16/06)
N.A.
2.03 (2004 Rate for Same Type of Roadway)
C. Traffic Factors:
Average Daily Traffic
Traffic Controls
Pedestrian/Bicycle Traffic
Bicycle Lanes
On-Street Parking
Other
D. Roadway Factors:
Street Classification
Length of Segment
Roadway Width
Number of Lanes
Vertical Alignment
Horizontal Alignment
Sidewalks
Driveways
Street Li htin
21,010 -north of Lionshead Avenue (11/01/06); 20,864 -South of Lionshead Avenue (11/01/06)
Traffic Signals at Palomar Airport Road and at Lionshead Avenue
Light
Bicycle Lane on Each Side
Parking Prohibited on Each Side
Bike Route per Circulation Element of the General Plan; Truck Route
Prime Arterial
0.34 mi.
Curb-to-Curb Width Varies Between 106 Feet and 118 Feet
Varies Between 3 and 4 Lanes Each Direction •
6.47% Maximum Centerline Grade
Three Horizontal Curves have a 2,000' Radius Each and One Horizontal Curve has a 2,200' Radius
Sidewalk on Each Side
One Driveway on West Side at Lionshead Avenue
Street Li hts on Each Side
E. Special Conditions: Travel lanes are separated by a raised, landscaped median. Southbound travel lanes are reduced from
three to two throu h lanes at Palomar Air ort Road.
F. Ad'acent Land Uses: Li ht industrial, icnic area, open s ace, future 100,000+ s uare foot office buildin
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
for Streets and Highways (FHWA's MUTCD 2003 Revision 1, as amended for use in California) with respect to design and
prevailing speeds, accident records, pedestrian and bicyclist safety, intersection and driveway spacing, and roadside and traffic
conditions not readil a arent to the driver. As eed limit ostin of 55 MPH is found to be a ro riate and ·ustified.,
I.
DATE: 11/02/06 TIME: 10:50 AM TO
WEATHER: Sunny & Mild
(
CITY OF CARLSBAD
SPEED SURVEY
11:25 AM TOTAL VEHICLES:
CRITICAL SPEED:
LOCATION: Melrose Drive~450' s/o Lionshead Avenue VEHICLES IN PACE:
OBSERVER/RECORDER: J. Gale ---------PACE SPEED(S):
NONE
POSTED SPEED LIMIT
NORTHBOUND
DIRECTION OF TRAVEL
MPH • # % I:# % %tile % #
65
64
63
62
61
60
59
58
57
56 X
55 X X
54 X
53 X X X
52 X X
51 X X X X
50 X X X X X
49 X X
48 X X X X X
47 X X X X X X
46 X X X X X
45 X X X X
44 X X
43 X X X X
42 X X X
41 X
40
39
38
37
36
35
34
33
32
31
30·
23
28
2T .. ----. ··--·--.
26
25
24
23
22
21
1 1 100 2 1
99
1 1 99 2 1
1 1 98 2 1
3 3 97 6 3
1 2 3 3 94 4 2
2 4 4 4 91 4 2
1 2 4 4 87 6 3
3 6 9 9 83 12 6
2 4 4 4 74 4 2
4 8 8 8 70 8 4
5 10 10 10 62 10 5
2 4 7 7 52 10 5
5 10 7 7 45 4 2
6 12 8 8 38 4 2
5 10 7 7 30 4 2
4 8 6 6 23 4 2
2 4 6 6 17 8 4
4 8 4 4 11
3 6 4 4 7 2 1
1 2 2 2 3 2 1
1 1 1 2 1
------. .. --· -
Engineering Department
Transportation Division
,_
100
54 MPH _____ _:_: ____ _
72 % -----------
44 TO 54 MPH ----------
SOUTHBOUND
DIRECTION OF TRAVEL
MPH
65
64
63
62
X 61
60
59
58
X X 57
X 56
X X Sq
X X X 54
X X X X X X 53
X X 52
X X X X 51
X X X X X 50
X X X X X 49
X X 48
X X 47
X X 46
X X 45
X X X X 44
43
X 42
X 41
X 40
39
38
37
36
• 35
34
33
32
31
30
29
28
--· ------... ··-· -·-----27
26
25
24
23
22
21