HomeMy WebLinkAboutReports #6 9-08-87 !i NO, 6
SEPTElqBER 1, 1987
TO: WILLIANHUSTON, CITY MANAGER
FROM: PUBLIC WORKS DEPARTNENT/ENGINEERING DIVISION
SUBJECT: REPORT ON REQUEST FOR ENGINEERING STUDY AND A TRAFFIC SIGNAL AT THE
INTERSECTION OF FIRST STREET AND 'B" STREET
RECOMMENDATION:
A traffic signal at the intersection of First Street and "B" Stree~ is not
recommended at this time because the intersection does not meet the minimum
required warrants which are used in determining the need for traffic signals.
However, it is recommended that another engineering study be performed after
school is in session and children are using the school crosswalk at this location.
Other interim recomendations include the installation of school crossing signs at
and in advance of the school crosswalk, extension of the existing red curb zone by'
1.5' in the northeast corner of the intersection and possible removal of the large
'ee in the southwest corner of the intersection.
BACKGROUND:
A request was made by City Council .to the Engineering Division to perform an
engineering study of the First Street and "B" Street intersection with regard to
impaired visibility, needed improvements and a warrant analysis for the possible
installation of a traffic signal.
EXISTING CONDITIONS:
First Street at the intersectin of "B" Street is a four lane arterial with a
raised median island a left-turn pockets. The left-turn pockets provide access to
both northbound and southbound traffic on "B" Street. In contrast, "B" Street
functions as a local residential street and has one lane of travel in each
direction. The speed limits on each street are 30 miles per hour (MPH) for First
Street and 25 MPH for "B" Street. In addition, there is an existing school
crosswalk which crosses First Street on the East side of the intersection. This
crosswalk is on the school route to the Helen Estock Elementary School.
Pedestrian counts were taken on First Street at two different time periods for a
total of four hours. The time periods counted were from 10:30 a.m. to 1:30 p.m.
and 4:30 p.m. to 5:30 p.m. The results are summarized as follows:
Number of
Location Ti me Peri od Pedestrians
First Street 10:30 a.m. - 1:30 p.m. 43
First Street 4:30 p.m. - 5:30 p.m. 19
· review of the accident data for a three year period (1984-1986) indicated that
three correctable accidents occurred at the First Street/"B" Street intersection.
Each accident was a right angle type of accident which is considered correctable
by the installation of a traffic signal. Of the three reported accidents, only
two resulted in an injury. However, there was one reported pedestrian accident at
the crosswalk on June 4, 1984.
In addition, a field review of this location indicated that a visiblity problem
does exist in the southwest and northeast corners of the intersection. In the
southwest corner, a large tree blocks the visibility of motorists stopped at the
stop sign from oncoming traffic on First Street. In the northeast corner,
vehicles parked in front of the commercial businesses to the east of "B" Street
~artially block the vision of motorists attempting, to drive through or make a
eft-turn onto First Street. This maneuver is oifficumt since-First Street
carries an average daily traffic volume of 26,000 vehicles per day.
EVALUATION:
he State of California Department of Transportation (Caltrans) has adopted eleven
(11) nationally recognized guidelines which are used in determining the need for
traffic signal control. These warrants define the minimum conditions under which
signal installations may be justified. Hence, the selection and use of a traffic
signal should )>e preceded by a thorough engineering study of roadway and traffic
conditions, coupled with the judgement of experienced engineers.
Each of the warrants were evaluated to see if the intersection of First Street/"B"
Street met the required minimum guidelines. The evaluation indicated that First
Street met the minimum traffic signal volume warrant for sixteen (16) of the
required eight (8) hours whereas "B" Street did not meet the volume warrant for
even one hour. In fact, none of the other (10) warrants were met, including the
accident experience warrant.
Based upon a field review of this intersection, three recommendations were
developed to improve existing conditions. The recommendations include the
extension of the red curb zone by 15' in the northeast corner of the intersection,
possible removal of the large tree in the southwest corner, and installation of
school crossing signs in advance and at the crosswalk.
Based upon the results of our engineering investigation, the installation of a
traffic signal is not warranted at this time. However, it is recommended that the
previously mentioned improvements be implemented. For informational purposes, we
have attached a copy of a report published by the Institute of Transportation
Engineers on traffic signals.
Bob Led6nd6cker Dennis D. Barnes
Director of Public Works/City Engineer City Traffic Engineer
BL/DDB/lg
Attachment
TRAFFIC SIGNALS
DOES SOMEBODY HAVE TO BE KILLED BEFORE A TRAFFIC SIGNAL
WILL BE INSTALLED?
Traffic signals don't always prevent accidents. They are not always an asset to traffic
control. In some instances, total accidents and severe injuries increased after signals were
installed. Usually, in such instances, right angle collisions were reduced by the traffic
signals, but the total number of collisions, especially the rear-end type, increased.
There are times when the installation of signals results in an increase in pedestrian
accidents. Many pedestrians feel sec. ure with a painted crosswalk and a red light betweer~
them and an approaching vehicle. The motorist, on the other hand, is not always so quick
to recognize these "barriers."
When can a traffic signal be an asset instead of a liability to safety? In order'to answer
this, traffic engineers have to ask and answer a series of questions:
1. Are there so many cars on both street~, that signal controls are necessary to
clear up the confusion or relieve the congestion?
2. Is the traffic on the main street so hea'~/that drivers on the side street will
try to cross when it is unsafe?
3. Are there so many pedestrians trying to cross a busy main street that
confusing, congested or hazardous conditions result?
4. Are there so many school children trying to cross the street at the same
time that they need special controls for their protection? If so, is a traffic signal
the best solution?
5. Are signals at this location going to help drivers maintain a uniform pace
along the route without stopping unnecessarily7