HomeMy WebLinkAboutCT 81-06B; POINSETTIA VILLAGE; TRAFFIC STUDY; 1986-02-07%k Lc4-1
TRA FFI C S TUD Y
FOR
PREPARED BY
SCHATZMANN, THOMPSON & ASSOC., INC.
1010 Linda Vista Drive Suite 203
San Marcos, CA 92069 (619) 744-1371 SURVEYING, CIVIL & TRAFFIC ENGINEERING
FEBI (986
S
SCHATZMANN, THOMPSON & ASSOC., INC.
1010 Linda Vista Drive Suite 203
San Marcos, CA 92069 (619)744-1371
SURVEYING, CIVIL & TRAFFIC ENGINEERING
February 7, 1986
Holmes & Reynolds Development Co.
839 West Harbor Drive Suite 1
San Diego, Ca. 92101
Attn: Fred Delaney
Re: Traffic Analysis for Poinsettia Village Commercial Center
Dear Fred:
This letter report will discuss the feasibility of allowing a
third access point to Poinsettia Village, the commercial
center located along the east side of Avenida Encinas.
Exhibit 1 shows the proked project design and the adjacent
road system. The access points are shown on this exhibit and
are numbered from north to south as Driveway No. 1, Driveway
No. 2 and Driveway No. 3. Driveway No. 1 and Driveway No.3
correspond to the existing locations of Loganberry Drive.
Loganberry Drive is proposed to be vacated and become part of
the private internal circulation for the development.
Driveway No. 2 would require an access openning as the access
rights were waived along Avenida Encinas as part of the
previous subdivision map. Driveway No. 2 is proposed to align
with the existing median break and with the main driveway to
the mobile home park located on the west side of Avenida
Encinas. Previous reports for this project were completed by
this office, dated September 27, 1985 and December 6, 1985,
and show trip generation factors, trip distribution, level of
service computations and probable location of future traffic
signals. These previous reports are included in the appendix
of this report.
Several key issuses exist as to whether Driveway No. 2 should
be allowed for this project. The City Engineering Departmerirt
staff feels that this additional access point should not be
allowed as it does not adhere to several design standards and
that an intersection cannot be safely placed on the inside of
a curve. One of the design standards in question is the
minimum intersection spacing. According to the City design
I
parameters for a Secondary Arterial, the classificati
o
n
o
f
Avenida Encinas, the minimum intersection spacin
g
i
s
6
0
0
feet. The existing median breaks are located at the
f
o
l
l
o
w
i
n
g
spacings; Poinsettia Lane to Driveway NO. 1
- 600 feet, Driveway No. 1 to Driveway No. 2
- 580 feet and Driveway No. 2 to Driveway No. 3 - 570 feet. As these median breaks are
existing and two of the breaks align with the drive
w
a
y
s
t
o
the mobile home park, the spacing could not be mod
i
f
i
e
d
a
s
part of this development. As design standards ar
e
g
e
n
e
r
a
l
guidelines there may be Instances which do
n
o
t
a
p
p
l
y
,
especially in areas where there are existing Improv
e
m
e
n
t
s
must be met. That is the case for the Poinsettia V
i
l
l
a
g
e
project where all of the improvements are exist
i
n
g
a
n
d
previously approved by the City of Carlsbad. The v
a
r
i
a
t
i
o
n
from these design standards, approximately 5%, Is
s
o
s
m
a
l
l
that the average driver would probably never
n
o
t
i
c
e
t
h
e
difference in intersection spacing along this
p
o
r
t
i
o
n
o
f
Avenida Encinas. Intersection spacing is a way
o
f
l
i
m
i
t
i
n
g
,'-the* number of access points along a street in an eff
o
r
t
t
o
control. the number of conflict points and incre
a
s
e
t
h
e
capacity of the roadway. Whether Driveway No. 2 is all
o
w
e
d
o
r
not there will still be the same number of Inter
s
e
c
t
i
o
n
s
along this portion of Avenida Encinas.
Another design parameter which the City Staff feels
t
h
a
t
t
h
i
s
development does not comply with deals with the a
l
i
g
n
m
e
n
t
o
f
Driveway No.. 2. The design criteria states as folo
o
w
s
:
Streets shall normally intersect at right angles
W
h
e
r
e
feasible, a local street shall have at least 50 feet
o
f
tangent adjacent to an intersection, measured from B.C.
R . Collectors should have at least 100 feet. Arterials wi
l
l
require special design. An angle of intersection of m
o
r
e
than 10* from right angle requires special approval
a
n
d
design. Hillside terrain will require special design.
Again this design standard is a guideline and is not
m
e
a
n
t
t
o
be strictly enforced to every situation. This can
b
e
s
e
e
n
b
y
the wording of the standard. The use of the words
s
h
a
l
l
a
n
d
feasible allow flexibility in this standard to meet sp
e
c
i
f
i
c
design considerations. Historically, the City Engi
n
e
e
r
i
n
g
Department has applied this criteria to determ
i
n
e
t
h
e
alignment of the minor Street at the intersectio
n
.
I
n
t
h
i
s
case It would apply to Driveway No. 2. The alignment o
f
t
h
e
major or through street was usually not controll
e
d
b
y
t
h
i
s
criteria. A look at the City of Carlsbad road system
w
i
l
l
show that there are numerous intersections which occur
w
i
t
h
i
n
or immediately adjacent .to a curve. This is true of
b
o
t
h
2
recent as well as older developments. The existing
improvements along Avenida Encirias are an example that this
standard has not been applied to the through steet. •Another
example would be Marron Road adjacent to the El Camino Real
Plaza where intersections are placed within curves. These are
only two specific examples however numerous other locations
could be listed throughout the City. The primary reason for
this standard is to provide adequate sight distance for the
motorist entering the intersection. The major or through
Street is designed to stricter standards and has a larger
sight distance requirement than the Intersecting minor
street.
The design of this development shows Driveway No. 2 to be
radial to the curve of Avenida Ericirias, which would equate to
a right angle intersection on a tangent section. Driveway No.
2 is also shown to be straight from the intersection easterly
into the project. This design would comply with the
Intersection design standard as it has been historically
enforced by-the City.
The Engineering Department Staff also feels that an
intersection cannot be savely placed on the inside of a
•.•..,- curve.. Again therare numerous intersections within Carlsbad
that are located on the inside of a curve. Some of these
locations could be considered problem locations and others
could be considered normal locations. The primary reason for
problems at these intersections Is that there is Insufficient
sight distance. As discussed In the original traffic report
for this commercial center it was noted that the major
concern in allowing this driveway was that adequate sight
distance may not exist, without special design
considerations. For that reason It was suggested that there
be a special setback for buildings, parking, slopes and
landscaping be maintained so the sight distance could be
provided at this location. A setback line which would provide
400 feet of sight distance was suggested for this location.
The setback lines are shown on Exhibit 2 as is the stopping
sight distance required by the City. The City standard for a
Secondary Arterial Is for a stopping sight distance of 275
feet. The larger value suggested for this project is to
allow a motorist leaving the center to better determine the
speed of the oncoming vehicle and enter the road without
causing the through motorist on Avenida Encinas to take
evasive action.
By providing this line of sight for the intersection the area
on the inside of the curve will have to remain clear of
3
obstructions, which will increase the sight distance along
Avenida Encinas in the area of the curve. This -will help to
improve the safety of the existing intersection as the sight
distance for through motorists will be longer than It Is
presently.
An example of an intersection located on the inside of a
curve which does not have sufficient sight distance Is the
southerly driveway of the mobile home park, located south of
this project. Due to the road curvature and the wall located
along the right of way, the sight distance is limited to
approximately 200 feet. At the present time this
intersecetion is not a problem as Avenida Encinas does not
continue southerly. Once Avenida Encinas continues southerly
to serve the Batiquitos Lagoon project there will be through
traffic which will increase the problems at this location.
The only way to eliminate the effects of the limited sight
distance is to remove the wall and possibly move several of
the coaches or close the driveway and direct all of the
traffic to one of the other two driveways.
As was previously discussed in both the original report and
Addendum No. #1 there will have to be a trafic signal
—installed at a minimum of one of the intersections serving
the commercial center. If Driveway No. 2 were to be
signalized it would serve both the commercial center as well
as the mobile home park. A signal at this location would
provide the best intersection spacing and produce the least
impact to through traffic along Avenida Encinas. If Driveway
No. 2 is not allowed there will probably have to be a signal
at both of the remaining driveways. This would cause a short
spacing between Poinsettia Lane and the first signal as well
as causing a second signal where Avenida Encinas traffic
would be subject to control and possible delay. The previous
reports have shown that the area would be operating at a
Level of Service C or better if the signal were to placed at
Driveway No. 2.
Another consideration In the design of this project was to
provide pedestrian access from the mobile home park to the
commercial center. This was a request of the Planning
Department. The pedestrian access was aligned with the main
driveway to the mobile home park. This aligns with the
primary atrraction of the center, the market. If Driveway No.
2 is allowed it will have to be signalized and will have
pedestrian functions. This will allow residents of the mobile
home park to easily cross Avenida Encinas. If Driveway No. 2
is not allowed many of the residents of the mobile home park
4
may still wish to cross at this location and due to the
curvature of the road and limited sight distance, if the
special setbacks required for the intersection do not exist,
a pedestrian would experience difficulty crossing Avenida
Encinas. The pedestrians would then have to cross at one of
the other intersections which would increase the distance and
travel time.
The existing alignment of Avenida Encinas does not conform to
all of the requirements of a Secondary Arterial. The
centerline radius is less than the 550 feet as required In
the standards. With a centerline radius of 500 feet and no
superelevatlon a design speed of 40 MPH cannot be achieved.
From Ca.ltrans design charts the design speed would less than
35 MPH as shown on Exhibit 3. Due to the existing
improvements being designed to less than Secondary Arterial
standards and the adjacent land use, residential and
commercial, the City should consider a reduced speed limit In
this. area. If a reduced speed limit were posted and the sight
distance of 400 feet was maintained from Driveway No. 2 the
project as proposed would exceed City requirements.
The project as proposed is similar to many locations
throughout the City where new developments try to tie into
existing Improvements. The developer tries to comply with all
of the design standards but due to existing Improvements
which cannot: be modified some of the standards must be
modified. The condition that Intersections should be 600 feet
apart does not seem to be a significant issue especially as
the variation is so small and the number of intersections
will, not be increased if Driveway No. 2 Is allowed. The
condition of the alignment of the Intersection seems to be
satisfied as Driveway No. 2 intersects Avenlda Encinas
radially, the equivalent of right angles, and the sight
distance is exceeded with the requiremnent of the setback
line. The development Is not asking for any Items which are
not present In recent developments throughout Carlsbad. It Is
not my belief that because something has been done before
that It should be allowed again, but with propoer design and
constraints this project would comply with normally accepted
practices in the Cityof Carlsbad and the region. The project
as proposed with the Driveway No. 2 being signalized and
special setback requirements would provide, In my opinion, a
safe Intersection for the general public as well as motorists
from the mobile home park and from Poinsettia Village. With
Driveway No. 2 the number of signals would be decreased which
would improve the spacing and improve the flow of traffic
along Avenida Encinas, as well as benefitting the existing
mobile home park. It would seem that Driveway No. 2 would be
the logical location for a driveway considering the existing
improvements along Avenida Encinas.
It should be noted that any intersection no matter what the
design will probably experience accidents. The greater the
volume of traffic the greater the chance of accidents. The
design of Driveway No. 2 as proposed would exceed the sight
distance requirements for a Secondary Arterial. It would seem
that reasonable care was taken In Increasing the parameters
in an effort to improve the safety of this intersection. A
signalized intersection would also make it easier for
pedestrian and vehicular traffic to Ingress and egress the
existing mobile home park as volumes along Avenida Encirias
increase.
If you have any questions or need additional information on
this item please feel free to contact me.
Sincerely,
Len Schatzmartn
Professional Engineer