SR-121366-8HF
CITY OF SANTA MONICA
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DATE: December g, 1966 _~ '
TO: Perry Scott, City Manager
FROM: Bartlett L. Kennedy, City Engineer '
SUBJECT: Traffic Signal Request - 20th Street at Delaware Avenue
In compliance with your verbal request, the Traffic Engineer
has conducted a study relative to the need for a traffic
signal at 20th Street .and Delaware Avenue. The results of
his study and his recommendations are contained in the
attached memo from the Parking and Traffic Engineer, subject
same as above.
The study has shown that a traffic signal at this location
can be justified due to increased traffic volumes and turning
movements at this intersection since the opening of the Santa
PRonica Freeway. In order to be effective, however, the in-
stallation of a traffic signal must be accompanied by certain
other changes in the traffic pattern, parking restrictions,
and signalization at other intersections and streets in the
area. These steps, listed as numbers "1" through "7",
inclusive, on pages 2 and 3 of the Traffic Engineers memo,
must be considered as a unit to be effective.
If it is the desire of the Council to proceed with this
improvement, an appropriation of funds will not be required
at this time. There is a possibility that State Highway
funds may be made available for half of the cost of the
signal. The design of the system can be under way while the
source of funds is being determined. This signal can be
included with the other signals already authorized in this
year's budget and as a part of the County Gasoline Tax
program and funds for its construction can be appropriated
if necessary at the time the contract is awarded.
BLK:fs
Attachment : PRemo
BARTLETT L, KENNEDY
City Engineer
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uATE: December 8, 1966
x~fl; City En cineer
gpv~-q; Parking & Traffic Engineer
SUBJECT: Traffic Signal ;xequest - 20th Street & Delaware Avenue.
This office has received a request from officials of "Project Head
Start" urging the installation of traffic control signals at the
above named intersection. in their letter of 'request they point out
that, in their opinion, some urgency exists -relative to their own
plans of expanding their existing pre-school classroom activities
with the construction, of additional classroom facilities. Conditional
use permits have been granted for this expansion.
i~7e 'rave conducted traffic studies of peak hour and average daily
traffic movements, and we have reviewed the accident history of the
intersection. Based on our -review of all related factors, I would
submit these comments.
1} ACCIDENTS:
During calendar years 1963 to 1905 t'rere were 2 accidents at
this intersection resulting in personal injuries, both of a
type correctible by signal control. Additionally, during
the same 36 month period there were 10 accidents resulting
in property damage only. Of these i0, 4 were 'right angle
type collisions which may have been prevented by signal
control.
Sn the 11 months since the opening of the Santa Monica Free-
way (January 4, 1966} t'rere have been no injury accidents,
however, there have been 8 property damage accidents, 6 of
which were right angle collisions. The other 2 accidents
in 1966 and 3 of the 10 accidents prior to the opening of
t'r~e Freeway, involved left-turn maneuvers from 20th Street
into Delaware Avenue.
2) T GAFF 1C VOI,U1iES:
Prior to the opening of the Freeway, traffic volume on 20th
Street was approximately 8,800 vehicles per day, with approx-
imately 800 to 850 vehicles per hour during both the A,M® and
P.M, peak periods. We have no record of left-turn volumes or
pedestrian activity for this point in time.
Since tine opening of the Freeway, traffic volumes on 20th St.
have risen to approximately 12,400 vehicl=s per day, avi.ui7
December 8, 1966
City Engineer
Traffic Sirnal Request - 20th
Street & Delaware Avenue
Page 2
1,200 to 1,250 vehicles per hour in the P.P~I® ioeak period.
The A.M, peak period has dropped to approximately 500
vehicles per Hour.
Tra1i-:~.C VO!L'tieS On De.'',.aW'.^e Stru-e't are nOw c-1pprOXliTtote.';,y
2,E30v per day, with 200 to 250 vehicles per hour during
both A„i~i. and P.NI, peak periods. There :is no comparative
record of Delaware Street volume prior to the Freeway
opening.
3j PEDESTRT~ti'S:
Traffic counts on Tuesday, Dece.-aber 6, indicate an average
of 7 pedestrians per hour c'rossing' 20th Street during peak
"tr aifl0 COndltlO.:S. Yi'.OSJeVer, 'th1S CO uTlt WdS maC2 dU ring
inclement weather conditions and may be :Lower than a court
on a clear clay, In any evert, it Would not seem that there
is sufficient pedestrian crossing demand to be a factor in
detersnini;,g need fo'r signal protection.
Sri GEOMETRICS:
nS yOii ]CHOW, tills interSeCtiOn iS apprOX i„tat ely at the Crest
of a hill, which 'results in limiting sig'rt distance along
20th Street.
This location is approximate:_y 1200 feet from existing fixed
time signals on 20th Street at O1y_~anic Blvd. and at Pico.
Blvd. This spacing would permit signalizatior. without unduly
lnterruptingg 2Oi.h Street traif_c by permit"ling a 27 mile per
hour speed of signal progression in both directions along
20th Street.
5 j OTI~R ~~ ~ CT ORS °
r.ny decisions reached concerning this specific intersection
r.~ust be weighed in t_e light.o•~ the potential effect of such
action on the intersection of Delaware Avenue & Cloverfield
elv~1° This later intersection is already one of the more
heava.ly congested spots in the City, and steins must be taken
to relieve traffic conditions here at an early date.
rafter glvlnq consideratior. tO all Of rite a'IJOVe faCtOrS, It iS i'lerewitil
reccr~u;lended t~.at.
=% ?: tra`r1C S1Cnai lie c:uthCrized a't %h e li.terSeCtiOn Of Delaware
Avenue and 20th Street and that provision be made on the signal
UO provide a separate left-turn phase 2Or sou%nbound traffic.
2; Par;cing on 20th Street between 'tne Sai^ta Moriea ~reecaay and a
pO 1.i7L T 200 :`.'C. SO::th Of Del aS•lare SCr.°.et be prOhlblted a`.. all
tires.
Decemoer 8, 1960
City,Engineer
Traffic Signal Reauest - 20th
Street ~ Delawa.re Avenue
3) T_ne lane markings
left-turn poc',cets
4) Delaware Avenue b
barking pe-rmitted
Cloverfield Blvd.
Page 3
on 20th Street be modified to provide
on eft'her side of Del a*aare Avenue.
made a one-way, eastbound street, with
on :ooih sides, between 20th Street and
5) Virginia Avenue be made a one-way westbound street with
parking prohibited on the south side bet"reen C1o=.rerfield
Blvd.. & 20th Street.
o) Pavement markings for southbound traffic on Cloverfieid
Blvd. be modified to perm~i'-
2 lanes to a~rn left onto the
Santa Monica Freeway.
7) The existing signal coniroller at Cloverfield Blvd. and
Delaware Street :oe modified to control both the ^reeway
off-ramp and the Delaware-Cloverfield intersection.
zf these ,-ecommendations are approved, this office will begin prepara-
tion o£ detail plans and estimates to perform the wor;c outlined herein.
On the basis of preliminary estimates, it would appear that the signal
proposed for 20th & Delavare would cost approximately $10,000 to install.
The modifications proposed at Delaware and Cloverfield would cost approx-
imately $5,000 capital outlay, but an existing semi actuated controller
would be salvaged for use elsewhere at a savings on some future project
of approximately $2,000. Inas,r~ch as both 20th Street and Cloverf~.eld
Blvd, are major streets on the City's Select Street System, these funds
can, as I understanc'., either be direct Gas Tax Projects, or can be
installed by the City on a matc~ing fund basis nor later credit.
~„
- Joseph D. L~?adon
Parxing & Traf°ic Engineer
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JDN e 11