Intelligent Transportation System

Traffic signal coordination is a method of timing groups of traffic signals along a major roadway to provide for a smooth flow of traffic with minimal stops. The goal of coordination is to get the greatest number of vehicles through a system— a group of coordinated traffic signals —with the fewest number of stops.

While it would be ideal if every vehicle entering the system could proceed through without stopping, this is not possible even in a well-spaced, well-designed system.

Not all streets warrant traffic signal coordination. Typically, a street is selected for coordination if it carries a certain amount of traffic during peak hours. In most cases, coordination is active from 6 a.m. to 7 p.m. during weekdays. Outside of these hours, individual signals operate on a “first-come-first-served,” or traffic activated, basis.

Coordination along a roadway corridor takes into account the spacing of signals, the prevailing speed and traffic volume on the corridor, the amount of traffic coming in and out of driveways between traffic signals, the uniformity of intersection sizes, and the traffic signal cycle length.

Generally speaking, “majority rules” in traffic coordination, and the busiest traffic movements are given priority.

Depending on the route, the length of a traffic signal cycle (think “green-yellow-red”) on a major roadway could vary from 60 to 120 seconds. This means that if you were exiting a side street, and you just missed the light, it is possible to wait between 60 and 120 seconds before receiving another green light. For the most part, the and bigger the intersection the longer the required cycle length.

Intelligent Transportation Systems, or ITS, is the use of technology to improve traffic flow. By using high-tech traffic communications (e.g., signal controllers and traffic cameras), traffic engineers can monitor real-time conditions, make modifications to signal operations and be alerted to problems with the traffic signal system. When heavy conditions occur, ITS can be used to modify the operation of a traffic signal and then alert motorists of potential problems via Changeable Message Signs and internet-based information tools. Thanks to ITS, traffic engineers can now respond more quickly to safety issues or problems with traffic signals by instantly viewing a camera closest to the intersection.

Roseville's ITS has five main components:

• 60 miles of fiber optic and 27 miles of high-speed copper communications
• 171 intelligent traffic signals
• 175 traffic monitoring cameras
• 9 electronic message boards
• Traffic Operations Center where all components are managed

The Roseville ITS Master Plan Project was the first step in establishing a fully deployed multi-modal ITS program.

Previous project reports defined Roseville’s ITS Concept of Operations which presents strategies for achieving the City's ITS vision, goals, and objectives. This final report built on the ITS Concept of Operations by presenting a detailed deployment plan for implementing the City's ITS strategies.

Descriptions of each of the recommended projects along with a preliminary implementation timeline and cost estimate can be found in the ITS Master Plan.

In addition, matrices are presented which map each project to specific ITS strategies and geographic corridors.

• Reduces corridor congestion by rapidly detecting and responding to traffic incidents.
• Reduces travel times, stops and delays by dynamically adjusting traffic signals in response to changing traffic conditions.
• Alerts motorists, pedestrians, bicyclists, commercial vehicles, and transit operators of congestion by collecting, processing and disseminating real-time information.
• Provides real-time transit arrival and departure information to passengers allowing them to time their departure from work or home to the transit stop.

The demand for mobility is often met by building more highways and bridges and adding more lanes to roads and streets in our cities. Although road widening can be very effective in in reducing traffic congestion, additional ways of managing traffic need to be considered to further enhance the efficiency of the roadway network.

ITS provides new tools to augment traditional transportation improvements. Use of ITS tools and strategies, the next major evolutionary stage of surface transportation, is expected to be the focus of major metropolitan area implementation efforts over the next several years, much like the highway system program was the focus of the last 60 years. Implementing ITS is one of the most cost effective ways to augment a roadway Capital Improvement Program and obtain a more efficient transportation system.

ITS applications represent a significant opportunity to improve the efficiency and safety of the surface transportation system in Roseville. These applications primarily improve the operation of a transportation system by either performing a function faster or more reliably, or by providing a service that was not previously available. In so doing, ITS provides for improved mobility of people and goods on the roadway network.

Roseville's goal is to have at least 70% of intersections at level C or better.