HomeMy WebLinkAbout2010-08-02; Traffic Safety Commission; ; Investigate the need to install a stop sign on Yosemite Street at its intersection with Valewood AvenueC
CITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
COMMISSION MEETING OF: August 2, 20 I 0
LOCATION:
INITIATED BY:
Yosemite Street at Valewood A venue
Sue Dewulf
2634 Valewood Avenue
Carlsbad, CA 92010
ITEM NO. 6C
REQUESTED ACTION: Investigate the need to install a stop sign on Yosemite Street at its
intersection with Valewood A venue.
BACKGROUND:
Yosemite Street intersects Valewood Avenue in a T-intersection configuration in a
residential area with Yosemite Street being considered the "stem" of the T-intersection.
Valewood Avenue is considered the "top" of the T (see Exhibit I). Currently this
intersection is uncontrolled on all approaches.
DATA:
Yosemite Street and Valewood A venue are located in the northeast portion of the city.
Both are unclassified on the Circulation Element of the General Plan but function as local
streets based on street width and adjacent land uses. These streets serve a residential
neighborhood comprised of single family homes. Both Yosemite Street and Valewood
Avenue have a curb-to-curb width of 40 feet with gutter and sidewalk on both sides.
Each stop sign request received by staff is analyzed based on standards and guidelines
found in the California Manual on Uniform Traffic Control Devices (MUTCD) and the
Cal trans Highway Design Manual. Stop signs, if improperly used, can cause substantial
inconvenience to drivers and should be used only where warranted. One of the conditions
that may warrant consideration of installing a stop sign on the minor street is when the
safe approach speed to the intersection is less than IO miles per hour, which is a result of
restricted visibility for the driver. The minor street at a T-intersection is generally
considered to be the stem of the T-intersection with the major street being the top of
the T. For the purpose of this report, Yosemite Street will be considered the minor street
as the stem of the T-intersection. Valewood Avenue will be considered the major street
as the top of the T-intersection.
Approach volumes obtained on May 25, 2010 at the intersection of Yosemite Street and
Valewood Avenue are shown in Table A.
Page I
CITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
COMMISSION MEETING OF:
( continued)
August 2, 2010
Time
NB
0000-0100 I
0100-0200 0
0200-0300 0
0300-0400 I
0400-0500 3
0500-0600 8
0600-0700 10
0700-0800 29
0800-0900 12
0900-1000 7
1000-1100 14
1100-1200 11
1200-1300 17
1300-1400 10
1400-1500 16
1500-1600 13
1600-1700 16
1700-1800 13
1800-1900 17
1900-2000 9
2000-2100 6
2100-2200 4
2200-2300 4
2300-2400 0
Totals 221
Table A
Yosemite Street and Valewood Avenue
24-Hour Intersection Approach Volumes
May 25, 2010
Yosemite Street Valewood Avenue
n/a Subtotal EB WB Subtotal
I 2 0 2
0 0 0 0
0 2 2 4
I I 0 I
3 I 1 2
8 0 2 2
IO 3 3 6
29 17 22 39
12 11 2 13
7 9 9 18
14 8 2 10
11 20 1 21
17 15 2 17
10 I I 7 18
16 35 13 48
13 26 IO 36
16 22 4 26
13 44 9 53
17 21 5 26
9 14 2 16
6 19 1 20
4 10 I 11
4 4 I 5
0 3 0 3
221 298 99 397
ITEMNO.6C
Total
Approach
Volume
12
1
1
0
11
13
35
92
86
89
79
79
78
80
98
93
103
150
110
99
90
66
41
26
618
Staff conducted an investigation at this intersection to determine if an all-way stop is
warranted. A multi-way stop analysis considers such factors as traffic volumes, collision
history and delay and to a lesser extent, intersection geometry and visibility. There have
been no reported collisions at the subject intersection from January 1, 2008 through April
30, 2010. None of the criteria for an all-way stop was satisfied therefore staff does not
recommend installation of an all-way stop at the intersection of Yosemite Street and
Valewood Avenue.
As drivers approach an uncontrolled intersection, they have right-of-way assignment
based upon the rules of the road. However, the driver should have an unobstructed view
of the entire intersection and sufficient distance along the line of sight at the intersecting
street for the driver to anticipate and avoid conflicts with approaching vehicles.
Page 2
CITY OF CARLSBAD
TRAFFIC SAFETY COMMISSION
STAFF REPORT
COMMISSION MEETING OF:
( continued)
August 2, 2010 ITEM NO. 6C
When a driver on the minor street is traveling towards the major street, a decision point is
required to determine whether braking to a stop is necessary because of an approaching
vehicle on the major street. This decision point location on the minor street must allow
the driver sufficient distance to view to both the right and left the approaches on the
major street. The driver on the minor street, generally not having the right-of-way, can
then initiate actions to slow, stop, or avoid a conflict with other vehicles, as necessary,
when sufficient comer sight distance is provided (see Exhibit 2).
The standard comer sight distance discussed in the Caltrans Highway Design Manual
provides 7-½ seconds for the driver on the minor street (Yosemite Street) to complete the
necessary maneuver (right or left tum) without requiring traffic on the major street
(Valewood Avenue) to radically alter their speed. The Caltrans Highway Design Manual
also acknowledges that in some cases, where restrictive conditions exist, the cost to
obtain 7-½ seconds of comer sight distance may be excessive, and a lesser value of
comer sight distance may be used. In such cases, the minimum value for comer sight
distance is equal to the stopping sight distance ( copies of the appropriate pages of the
Caltrans Highway Design Manual are attached).
For the analyses of local streets, the minor street decision point is assumed to be 50 feet
from the intersection given the vehicle on the minor street has an approach speed of
10 miles per hour. A distance of 150 feet (stopping sight distance for 25 miles per hour)
along the major street must be provided to minor street drivers to view vehicles
approaching the intersection.
At the study intersection, sight distance from Yosemite Street looking to the west was
measured to be 124 feet, which is less than the required 150 feet. The sight distance
limitation is due to the horizontal alignment of Valewood A venue west of the
intersection. Sight distance looking to the east was found to be more than 600 feet, which
is more than the 150 foot minimum requirement.
Based on these findings, staff determined that the 10-mile per hour safe approach speed
criteria is not being met for northbound Yosemite Street drivers and a stop sign can be
considered for installation on Yosemite Street at Valewood Avenue.
RECOMMENDATION:
Based on the findings contained in this report, the Traffic Safety Coordinating Committee
recommends the installation of a stop sign on Yosemite Street at its intersection with
Valewood Avenue. This would include a striped limit line and "STOP" pavement legend
placed on the roadway.
NECESSARY CITY COUNCIL ACTION:
The City Council must adopt an ordinance to establish the stop control as recommended.
Page 3
~
LOCATION MAP
(l
PROPOSED
STOP LOCATION
C~?\\~~
w
~
0 Cl
l.J_
.....I <(
I
SUTTER ST.
~ SAUSAL\10 AVE. _ __,,
NOT TO SCALE
PROPOSED STOP SIGN ON
YOSEMITE STREET AT VALEWOOD AVENUE
"lJ
0 z
-I
)>
0
0 ::::0
EXHIBIT
1
0 c::. ~
I
t e
J
I • = {
I t l t ! .I!
REQUIRED
LINE OF SIGHT
VALEWOOD
AVENUE
150' REQUIRED
124' MEASURED
........ ....
MEASURED
LINE OF SIGHT
w 1--f-2W ww
(f) 0:::
Of->-(f)
CONFLICT
POINT VALE WOOD
DECISION
POINT
AVENUE
600' + MEASURED
150' REQUIRED
--REQUIRED --LINE OF SIGHT
---MEASURED I
w f--1-2 W ww V1 0::: 01->-(f)
-
DECISION
POINT
LINE OF SIGHT
DATE Of MEASUREMENTS: 5/12/10
YOSEMITE STREETNALEWOOD AVENUE
SIGHT DISTANCE ANALYSIS
EXHIBIT
2
i
j
I
1 I
l .__ ______________________ .;.... ____________ ___,..11
HIGHWAY DESIGN MANUAL 200-1
January 4, 2007
CHAPTER 200
GEOMETRIC DESIGN AND
STRUCTURE STANDARDS
Topic 201 -Sight Distance
Index 201.1 -General
Sight distance is the continuous length cif highway
ahead visible to the driver. Four types of sight
distance are considered here: passing, stopping,
decision, and comer. Passing sight distance is used
where use of an opposing lane can provide passing
opportunities (see Index 201.2). Stopping sight
distance is the minimum sight distance to be
provided on multilane highways and on 2-lane
roads when passing sight distance is not
economically obtainable. Stopping sight distance
also is to be provided for all elements of
interchanges and intersections at grade, including
private road connections (see Topic 504, Index
405.1, & Figure 405.7). Decision sight distance is
used at major decision points (see Indexes 201.7
and 504.2). Comer sight distance is used at
intersections (see Index 405.1, Figure 405.7, and
Figure 504.3J).
Table 201.1 shows the standards for stopping
sight distance related to design speed, and these
shall be the minimum values used in design.
Also shown are the values for use in providing
passing sight distance.
Chapter 3 of "A Policy on Geometric Design of
Highways and Streets," AASHTO, contains a
thorough discussion of the derivation of stopping
sight distance.
201.2 Passing Sight Distance
Passing sight distance is the m1mmum sight
distance required for the driver of one vehicle to
pass another vehicle safely and comfortably.
Passing must be accomplished assuming an
oncoming vehicle comes into view and maintains
the design speed, without reduction, after the
overtaking maneuver is started.
Table 201.1
Sight Distance Standards
Design Speect'1) Stopping<2) Passing
(mph} (ft) (ft)
20 125 800
25 150 950
30 200 1,100
35 250 1,300
40 300 1,500
45 360 1,650
50 430 1,800
55 500 1,950
60 580 2,100
65 660 2,300
70 750 2,500
75 840 2,600
80 930 2,700
(1) See Topic 10 I for selection of design speed.
(2) For sustained downgrades, refer to advisory standard in
Index 201.3
The sight distance available for passing at any
place is the longest distance at which a driver
whose eyes are 3 ½ feet above the pavement
surface can see the top of an object 4 ¼ feet high
on the road. See Table 201.1 for the calculated
values that are associated with various design
speeds.
In general, 2-lane highways should be designed to
provide for passing where possible, especially
those routes with_ high volumes of trucks or
recreational vehicles. Passing should be done on
tangent horizontal alignments with constant grades
or a slight sag vertical curve. Not only are drivers
reluctant to pass on a long crest vertical curve, but
it is impracticable to design crest vertical curves to
provide for passing sight distance because of high
cost where crest cuts are involved. Passing sight
distance for crest vertical curves is 7 to 17 times
longer than the stopping sight distance.
Ordinarily, passing sight distance is provided at
locations where combinations of alignment and
HIGHWAY DESIGN MANUAL 400-17
July 24, 2009
Topic 405 ~ Intersection Design
Standards
405.l Sight Distance
(1) Stopping Sight Distance. See Index 2O1.l for
minimum stopping sight distance requirements.
(2) Corner Sight Distance.
(a) General--At unsignalized intersections a
substantially clear line of sight should be
maintained between the driver of a vehicle
waiting at the crossroad and the driver of
an approaching vehicle.
Adequate time must be provided for the
waiting vehicle to· either cross all lanes of
through traffic, cross . the near lanes and
turn left, or tum right, without requiring
through traffic to radically alter their
speed.
The values given in Table 405.lA provide
7-1 /2 seconds for the driver on the
crossroad to complete the necessary
maneuver while the approaching vehicle
travels at the assumed design speed of the
main highway. The 7-1/2 second criterion
is nonnally applied to all lanes of through
traffic in order to cover all possible
maneuvers by the vehicle at the crossroad ..
However, by providing the standard comer
sight distance to the lane nearest to and
farthest from the waiting vehicle, adequate
time should be obtained to make the
necessary movement. On multilane
highways a 7-1/2 second criterion for the
outside lane, in both directions· of travel,
normal1y will provide increased sight
distance to the inside lanes. Consideration
should be given to increasing these values
on downgrades steeper than 3 percent and
longer than 1 mile (see Index 201.3),
where there are high truck volumes on the
crossroad, or where the skew of the
intersection substantially increases the •
distance traveled by the crossing vehicle.
In determining comer sight distance, a set
back distance for the vehicle waiting at the
crossroad must be assumed. Set back for
the driver on the crossroad shall be a
minimum of 10 feet plus the shoulder
width of the major road but not less
than 15 feet. Comer sight distance is to be
measured from a 3.5-foot height at the
location of the driver on the minor road to
a 4.25-foot object height in the center of
the approaching lane of the major road. If
the. major road has a median barrier, .a
2-foot object height should be used to
determine the rnedian barrier set back.
In some cases the cost to obtain
7-1 /2 seconds of comer sight distances
may be excessive. High costs may be
attributable to right of way acquisition,
building removal, extensive excavation, or
immitigable environmental impacts. In
such cases a lesser value of comer sight
distance, as described under the following
headings, may be used.
(b) Public Road Intersections (Refer to
Topic 2O5)--At unsignalized public road
intersections (see Index 405.7) corner sight
distance values given in Table 405. IA
should be provided.
At signalized intersections the values for
comer sight distances giyen in
Table 405. lA should also be applied
whenever possible. Even though traffic
flows are designed to move at separate
times, unanticipated vehicle conflicts can
occur due to violation of signal, right turns .
on red, malfunction of the signal, or use of
flashing red/yellow mode.
Where restrictive conditions exist,
similar to those listed in
Index 405.l(l)(a), the minimum value
for corner sight distance at both
signalized and unsignalized intersections
shall be equal to the stopping sight
distance as given in Table 201.1,
measured as previously described.
(c) Private Road Intersections (Refer to
Index 205.2) and Rural Driveways (Refer
to Index 205.4)--The minimum corner
sight distance shall be equal to the
stopping sight distance as given in
400-18
July I, 2008
HIGHWAY DESIGN MANUAL
Table 201.1, measured as previously
described.
(d) Urban Driveways (Refer to Index 205.3)--
Comer sight distance requirements as
described above are not applied to urban
driveways.
(3) Decision Sight Distance. At intersections
where the State route turns or crosses another
State route, the decision sight distance values
given in Table 201.7 should be used. In
computing and measuring decision sight
distance, the 3.5-foot eye height and the
0.5-foot object height should be used, the
object being located on the side of the
intersection nearest the approaching driver.
The·-application of the various sight distance
requirements for the different types of
intersections is summarized in Table 405.1 B.
(4) Acceleration Lanes for Turning Moves onto
State Highways. At rural intersections, with
stop control on the local cross road,
acceleration lanes for left and right turns onto
the State facility should be considered. At a
minimum, the following features should be
evaluated for both the major• highway and the
cross road:
• divided versus undivided
• number oflanes
• design speed
• gradient
• lane, shoulder and median width
• traffic volume and composition
• turning volumes
• horizontal curve radii
• sight distance
proximity of adjacent intersections
• types of adjacent intersections
For additional information and guidance, refer
to AASHTO, A Policy on Geometric Design of
Highways and Streets, the Headquarters Traffic
Liaison and the Design Coordinator.
Table 405.1A
Corner Sight Distance
(7-1/2 Second Criteria)
Design Speed
(mph)
25
30
35
40
45
50
5S
60
65
70
Corner Sight
Distance (ft)
27S
330
385
440
495
S50
605
660
71S
770
Table 405.1B
Application of Sight Distance
Requirements
Intersection
TyPes
Private Roads
Public Streets and
Road_s
Signalized
Intersections
State Route Inter~
sections & Route
Direction
Changes, with or
without Signals
Sight Distance
Stopping Comer Decision
X X
X (2)
X X X
(I) Using stopping sight distance between an eye height of3.5 ft and an
object height of 4.25 ft. See Index 405. l (2){a) for setback
requirements.
(2) Apply corner sight distance requirements at signali2ed intersections
whenever possible due to unanticipated violations of the signals or
malfunctions of the signals. See Index 405.1 (2Xb ).
California MUTCD Page 2B-4
(FHWA's MUTCD 2003 including Revisions I and 2, as amended for use in California)
Where there is a marked crosswalk at the intersection, the STOP sign should be installed in advance of
the crosswalk line nearest to the approaching traffic.
Option:
At wide-throat intersections or where two or more approach lanes of traffic exist on the signed approach,
observance of the stop control may be improved by the installation of an additional STOP sign on the left
side of the road and/or the use of a stop line. At channelized intersections, the additional STOP sign may be
effectively.placed on a channelizing island.
Support:
Figure ~ 2A-2(CA) shows examples of some typical placements of STOP signs.
Standard:
When a required stop is to apply at the entrance to an intersection from a one-way street with a roadway of
9.1 m (30 ft) or more in width, stop signs shall be erected both on the left and the right sides of the one-way
• street at or near the entrance to the intersection. Refer to eve 21355.
Section 2B.07 Multiway Stop Applications
Support:
Multiway stop control can be useful as a safety measure at intersections if certain traffic conditions exist.
Safety concerns associated with multiway stops include pedestrians, bicyclists, and al.I road users expecting
otherroad users to stop. Multiway stop control is used where the volume of traffic on the intersecting roads
is approximately equal.
The restrictions on the use of STOP signs described in Section 2B.05 also apply to multiway stop
applications.
Guidance:
The decision to install multiway stop control should be based on an engineering study.
The following criteria should be considered in the engineering study for a multiway STOP sign
installation:
A. Where traffic control signals are justified, the multiway stop is an interim measure that can be
installed quickly to control traffic while arrangements are being made for the installation of the traffic
control signal.
B. A crash problem, as indicated by 5 or more reported crashes in a 12-month period that are susceptible
to correction by a multiway stop installation. Such crashes include right-and left-tum collisions as
well as right-angle collisions.
C. Minimum volumes:
l. The vehicular volume entering the intersection from the major street approaches (total of both
approaches) averages at least 300 vehicles per hour for any 8 hours of an average day, and
2. The combined vehicular, pedestrian, and bicycle volume entering the intersection from the minor
street approaches (total of both approaches) averages at least 200 units per hour for the same 8
hours, with an average delay to minor-street vehicular traffic of at least 30 seconds per vehicle
during the highest hour, but
3. If the 85th-percentile approach speed of the major-street traffic exceeds 65 km/h or exceeds 40
mph, the minimum vehicular volume warrants are 70 percent of the above values.
D. Where no single criterion is satisfied, but where Criteria B, C.1, and C.2 are all satisfied to 80 percent
of the minimum values. Criterion C.3 is excluded from this condition.
Option:
Other criteria that may be considered in an engineering study include:
A. The need to control left-tum conflicts;
B. The need to control vehicle/pedestrian conflicts near locations that generate high pedestrian volumes;
C. Locations where a road user, after stopping, cannot see conflicting traffic and is not able to reasonably
safely negotiate the intersection unless conflicting cross traffic is also required to stop; and
D. An intersection of two residential neighborhood collector (through) streets of similar design and
operating characteristics where multiway stop control would improve traffic operational
characteristics of the intersection.
Chapter 2B -Regulatory Signs
Part 2 • Signs
January 21, 2010