The Traffic Division of the Engineering Department performs and provides services in a variety of professional and technical level traffic and transportation engineering tasks including: traffic (flow/congestion/collision) analysis, system planning, design and operation of traffic control systems and other miscellaneous traffic/transportation related duties as required.
If more detailed information is needed in regards to the duties of the Traffic Division of the Engineering Department refer to the list shown below.
* Please note that if any type of work is to be performed in the public right-of-way, including City funded projects, traffic control plans, conforming to the latest version of Cal Trans'
California Manual on Uniform Traffic Control Devices, must be submitted to the Traffic Engineer for approval.
Tasks and Duties
Citizen concerns/requests - respond , conduct traffic investigations
Speed zone surveys - determine speed limits
Traffic Count Program - for arterial streets and intersections Accidents monitoring- traffic collision database
Traffic Advisory Committee - reviews new signals, stop signs, speed zones, parking zones, policies, etc.
Traffic policies - review and recommend changes through Traffic Advisory committee and City Council
School area safety - participate with school to improve safety, recommend changes in signing , striping, and traffic control devices
Traffic signals- signal timing modifications and new signals
Traffic signal coordination systems - monitor and adjust timing - Bear Valley Road, Palmdale Road, 7th Street, and Roy Rodgers Drive Traffic Control Plans - review for construction activity.
Oversize load permits -restrict routes and time of travel
Development review - conditions of approval , site access, circulation, plan check for signing , striping, and traffic signals
Traffic studies - review for impacts and required mitigation such as new traffic signals
Congestion Management Program (CMP) - monitor and mitigate congested roads
City traffic forecast model - determines number of lanes for roads and intersections for master-planned streets
General plan circulation map - recommend changes for future needs
How does the City decide to install traffic signals?
While traffic signals can cost anywhere from $150k to $250k to install, depending on the intersection, cost is not usually a factor used to decide whether to make an intersection signalized. To install traffic signals for any intersection in California, the intersection must meet warrants as spelled out in the
Manual of Uniform Traffic Control Devices. Vehicular and pedestrian volume is the most common factor in most of the warrants. Other factors include speed control, accident records, proximity to a school zone, and traffic flow enhancement in progressive systems.
Why does the City have four-way stops?
The City tries to avoid four-way stops because of the great disadvantage of stopping all vehicles, thereby increasing unnecessary emissions of pollutants, consumption of fuel, and added noise. However, under certain special circumstances, four-way stop control may be suitable. These circumstances include where traffic signals are warranted and urgently needed but cannot yet get installed, when five or more accidents happen at an intersection within a 12-month period, and a formula based on vehicle and pedestrian volumes and where the approach speed on one of the streets exceeds 40 mph.
How does the City decide when and where to install stop signs?
A two-way stop is used where one of the streets at the intersection is obviously more heavily traveled. The stop sign is placed on the lesser street to protect the traffic on the more major street. They are also placed where reliance on the standard right of way rule is unduly hazardous, as indicated by high speeds, high accident records, or restricted view. Prior to applying this "warrant", less restrictive measures, such as a yield sign, should be considered.
What are the required warrants (criteria) for a yield sign?
The yield sign is used to protect traffic on one of two intersecting streets without requiring traffic on the other street to come to a complete stop. They are used on low volume roads where right-of-way rule at an intersection of a less-important road with a main road might not be readily apparent. Another reason might be where an intersection has restricted sight distance for the prevailing vehicle speeds.
How does the City decide to install traffic signals, yield or stop signs?
For an uncontrolled intersection, that has no signals, yield or stop signs, vehicles must follow the standard right of way rule per Uniform Vehicle Code (UVC)Ref. 1 §11-401 that states "When two vehicles approach or enter an intersection from different roads at the same time, the driver of the vehicle on the left shall yield to the vehicle on the right." When this standard rule is insufficient, usually for safety reasons, the intersection needs to be controlled. The level of control installed is based on criteria known as "warrants" regulated in the UVC and
Manual of Uniform Traffic Control Devices (MUTCD). All intersections in California must abide by these warrants.
Why does the City do so many different types of traffic counts?
Traffic volume studies are made to obtain factual data concerning the movement of vehicles and/or persons at selected points on the street system. Volume data are expressed in relation to time, the base being determined by the type of information desired and the application to which it is used. When doing a coordination study for weekend volumes, then a 7-day count will be ordered. Otherwise 24-hour counts are used since they are much less cost.
What is Traffic Engineering?
Traffic Engineering is the science of measuring traffic and travel, the study of basic laws relating to traffic flow and generation, and the application of knowledge to the professional practice of planning, designing and operating traffic systems to achieve safe and efficient movement of persons and goods