HomeMy WebLinkAbout1995-10-10 - AGENDA REPORTS - TRAFSIG PRIORITY RATING SYSTEM (2)City Manager Approval
Item to be presented by:
Bahman Janka
UNFINISHED BUSINESS
DATE: October 10, 1995
SUBJECT: TRAFFIC SIGNAL PRIORITY RATING SYSTEM
DEPARTMENT: Building and Engineering Services
In March 1995, the City Council directed staff to prepare a priority system to be used in ranking
the locations which meet traffic signal warrants. This report establishes the City of Santa
Clarita's Traffic Signal Priority Rating System.
The City of Santa Clarita, as with most cities experiencing rapid growth, faces an increasing
traffic congestion. Congestion means more control or traffic signals might be needed at
unsignalized intersections. With growth, therefore, comes an increased demand for more traffic
signals. In fact, the number of traffic signals in most cities has been shown to be directly
proportional to the cities' population.
In time, the citizens demand for traffic signal installations will exceed that for which the City
may have budget for.. To allocate City resources better, some type of priority system needs to
be established. The Traffic Signal Priority Rating System with thoughtful allocation of limited
funding sources can protect the City from tort -liability claims when accidents occur at candidate
locations.
At present, the City of Santa Clarita does not have a policy for ranking multiple intersections
that warrant traffic signalization. This proposed policy will generate a ranked list of warranted
traffic signal locations by assigning points based on factors, such as accidents, visibility,
distance to existing traffic signals, pedestrian activities, traffic volume, travel speed, adjacent
land uses and many others. It would indicate a relative measure of demand for installing traffic
signals at each of the warranted intersections.
Staff gathered priority rating information from the following major cities in California known
to have such systems:
Adopted: fD - i,, - 9 -sl
Agenda Item
TRAFFIC SIGNAL PRIORITY RATING SYSTEM
October 10, 1995 - Page 2
1.
County of San Diego
2.
City of Fremont
3.
City of San Jose
4.
City of Stockton
5.
City of San Diego
6.
City of Irvine
7.
City of Bakersfield
The Traffic Signal Priority Rating System will not replace the established state and federal
traffic signal warrants. It will be used for warranted traffic signal locations only. The ranked
traffic signal priority list generated by this system will be used by the City staff to make
recommendations for the installation of signals under various City improvement programs.
Most of the priority rating systems gathered have very similar criteria, except for the Cities of
San Jose's, Stockton's and Bakersfield's. Of the different systems studied, the City of Irvine's
and City of Fremont's system seemed to have the most relevant factors.
The rating system impartially ranks candidate traffic signal locations so limited funds can be
used for the most needed traffic signal. It provides a running inventory of intersections to be
resurveyed periodically for significant changes in operating conditions and also provides a
consistent and orderly basis for the installation of traffic signals.
The choice of a Traffic Signal Priority Rating System is not as important as having one.
Therefore, any of the systems studied can be readily adopted by the City of Santa Clarita to
generate a ranked traffic signal list. Based on ease of use, staff feels that a combination of the
City of Irvine's and City of Fremont's systems would be most suitable for our purpose with the
minor modifications.
The complete text of the proposed City of Santa Clarita Traffic Signal Priority Rating System
is shown in Attachment "A".
Adopt the attached Resolution No. 95-116, establishing the City of Santa Clarita's Traffic Signal
Priority Rating System.
Resolution No. 95-116
Attachment "A" - City of Santa Clarita Traffic Signal Priority Rating System
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RESOLUTION NO. 95-116
A RESOLUTION OF THE CITY COUNCIL
OF THE CITY OF SANTA CLARITA, CALIFORNIA,
ESTABLISHING TRAFFIC SIGNAL PRIORITY RATING SYSTEM
WHEREAS, Section 21351 of the California Vehicle Code permits local authorities
to place or cause to be placed, with respect to intersections under its exclusive jurisdiction,
traffic signals as may be necessary to control or direct traffic or to facilitate traffic flow; and
WHEREAS, The City's rapid growth will increase congestion and increase demand
for more traffic signal installation; and
WHEREAS, The demand for traffic signal installation in time, will exceed that
for which the City may have budget for; and
WHEREAS, To better allocate City funds, it is necessary to develop a Traffic
Signal Priority Rating System that would rank warranted traffic signals in the order of their
importance; and
WHEREAS, The Signal Priority Rating System with thoughtful allocation of
limited funding sources can protect the City from tort -liability claims when accidents occur at
candidate locations.
NOW, THEREFORE, the City Council of the City of Santa Clarita does resolve
as follows:
SECTION 1. That the Traffic Signal Priority Rating System as outlined in
Attachment "A" be established as a guideline for evaluating the relative ranking of all
warranted traffic signals Citywide.
SECTION 2. That staff conduct the necessary signal warrant studies at all
candidate intersections Citywide.
SECTION 3. That staff prioritize all intersections that meet traffic signal
warrants in accordance with the established Traffic Signal Priority Rating System.
PASSED, APPROVED AND ADOPTED this day of 1995.
MAYOR
ATTEST:
CITY CLERK
RESOLUTION NO. 95-116
October 10, 1995 - Page 2
STATE OF CALIFORNIA )
COUNTY OF LOS ANGELES ) §
CITY OF SANTA CLARITA )
I, Donna M. Grindey, City Clerk of the City of Santa Clarita, do hereby certify that the
foregoing Resolution was duly adopted by the City Council of the City of Santa Clarita at a
regular meeting thereof, held on the day of 1995 by the
following vote of Council:
AYES: COUNCILMEMBERS:
NOES: COUNCILMEMBERS:
ABSENT: COUNCILMEMBERS:
CITY CLERK
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ATTACHMENT "A"
City of Santa Clarita
Traffic Signal Priority Rating System
SELECTION OF CANDIDATE INTERSECTIONS
Intersections will be selected for a signal warrant review from the following list.
1. There was a citizen request for it.
2. It is an intersection which is conditioned to be signalized by developers, and substantial
adjacent land uses have been built and occupied.
3. Locations included in the signal priority list for the previous year which met at least one
traffic signal warrant.
4. Locations that have experienced five or more accidents during the recent 12 -month period
which are susceptible to correction by installation of traffic signals.
5. Selected locations by the Traffic Engineering Staff. This may include locations which were
studied in the previous year, but did not meet any traffic signal warrants.
WARRANT ANALYSIS
The State of California Traffic Manual has established 11 types of signal warrants to be studied
to assess if the minimum criteria for installing a traffic signal is met. At least one signal
warrant must be satisfied before a traffic signal can be installed at an intersection. Only seven
of the 11 traffic signal warrants which are most suitable for the Santa Clarita roadway and
traffic volume conditions will be used to evaluate whether a candidate location meets the
established criteria. These warrants are the following:
1.
1
Minimum Vehicular Volume
2.
2
Interruption of Continues Traffic
3.
4
School Crossings
4.
6
Accident Experience
5.
8
Combination of Warrants (80% of warrants 1 and 2)
6.
9
Four-hour Volume
7.
11
Peak -hour Volume
Those intersections that meet at least one traffic signal warrant will be assigned priority points
and ranked in the signal priority list.
Priority points are assigned on the basis of the following categories:
1. Category No. 1 Total Vehicular Volume
Points are dependent upon the major and minor street volumes entering the intersection.
Points are also dependent upon the intersection capacity. The volumes are based on the
eight highest hour counts. The attached Figure 1 assigns points to this category. A
maximum of 15 points may be assigned to this category.
.• ►. F•4 . I ITIair
Vehicles on through streets, if uncontrolled, tend to travel through minor street
intersections at speeds that might make it difficult for vehicles and pedestrians from the
side street to cross or enter the principal traffic stream. The total of the highest minor
street vehicles plus pedestrians crossing or entering the major street must exceed 600 in
eights hours to receive any points. A maximum of 15 points may be assigned to this
category.
Table 1
Major Street Volumes
0
- 3,299
0
3,300
- 3,899
1
3,900
- 4,499
2
4,500
- 5,099
3
5,100
- 5,699
4
5,700
- 6,299
5
6,300
- 6,899
6
61900
- 7,499
7
7,500
- 8,099
8
8,100
- 8,699
9
8,700
- 9,299
10
9,300
- 9,899
11
9,900
- 10,499
12
10,500
- 11,099
13
11,100
- 11,699
14
11,700
- Over
15
4
3.
4.
This is a judgment criterion; points are assigned based upon the knowledge of pedestrian
activity at the intersection and area characteristics, etc. A maximum of 15 points may be
assigned to this category according to the guideline shown in the following table:
Table 2
None Very low pedestrian volumes or locations in industrial
or rural areas with no sidewalks.
Light Residential or business area with light pedestrian
traffic.
Medium School crossing or business area with intermittent
pedestrian crossings throughout the day, or intersections
in the vicinity of schools or parks where school-age
pedestrian traffic has been observed.
Heavy Intersection crossing with continuous pedestrian traffic at
all hours of the day, including intersections where
adult crossing guards are posted or where criteria for
adult crossing guard warrants are met (posted or
not posted,) and intersections adjacent to City parks,
and where a severe or visible pedestrian injury accident
has occurred in the previous year.
Points
0
5
10
15
Category No 4 - Progressive Traffic Movement (Proximity to the nearest traffic signal)
Generally, it is difficult to attain progressive traffic movement when signals are spaced too
closely together. In addition, if an existing signal is located in close proximity to the
candidate intersection, that signal is likely to provide breaks in traffic that reduce the
need for a signal at the candidate intersection. Points for progressive traffic movement
are selected according to the distance to the nearest traffic signal as shown in the following
table-
Table 3
Less than 500 feet
0
500 -
549 feet
1
550 -
699 feet
2
700 -
849 feet
3
850 -
999 feet
4
1,000 -
1,149 feet
5
1,150 -
1,299 feet
6
1,300 -
1,449 feet
7
1,450 -
1,599 feet
8
1,600 -
1,749 feet
9
1,750 -
Over
10
3
5. Category No. 5. - Accident Experience
Only those type of accidents susceptible to correction by traffic signals are considered. A
maximum of 20 points may be assigned to this category. Points are assigned based on
Equivalent Property Damage Accidents (EPD) using the equation:
Aepd = P + 6I+ 9F, where
Aepd = The number of equivalent property damage accidents;
P = The number of property damage only accidents;
I = The number of severe or visible injury accidents; and
F = The number of fatal accidents.
These weights are based upon the relative costs of each type of accident as estimated by
the National Safety Council. Accidents for the preceding year are utilized for the
calculation.
6. Category No. 6 - Approach Speed
Points are awarded based on the critical speed (85th percentile speed) as measured on the
higher -speed street. Points are awarded in this category because of the difficulty that
motorists may have judging gaps in traffic on high-speed streets.
Table 4
85% Speed Points
39 and under
0
40-42
2
43-45
4
46-49
6
50-54
8
55 - Over
10
Category No. 7 - Street Geometrics
Points will be given to type of intersection and road type classification. Roadways are
typically classified as Local (L), Collector (C) and Arterial (A). For the purpose of this
category, local and collector streets will be rated identical. The idea for this point
assignment is to put high priority to major roadway intersections.
0
Table 5
Intersection Crossing Streets
Type Type Points
4 way
LULL 0
3 way
AA/L 1
3 way
AA/A 2
4 way
AA/LL 3
4 way
AA/AL 4
4 way
AAAA 5
. r ►. . • ... ...
This category considers extenuating circumstances that are not covered in the previous
seven categories. These may include: the proximity of schools, churches, public buildings,
and other traffic and pedestrian generators; the existence of a vertical or horizontal curve;
and restricted sight distance caused by intersection geometry. This category requires
engineering judgement based on physical inspection of the site. A maximum of 10 points
will be allowed as shown in the table below:
Table 6
I
Near church or senior center. 5
Blind intersections caused by vertical or horizontal curves.. 5
Skewed intersection (less than 75 degrees) 5
Near schools, parks or public buildings which did not receive 10
additional points in category 3
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