Operational Functions

The arterial traffic management infrastructure investments require careful operations to be effective. While agencies in the MAG Region are primarily responsible for operating systems on arterials within their jurisdiction, there has been a very focused effort to improve regional operations strategies through coordinated practices, sharing data among agencies, and collaborating on cross-jurisdictional arterial operations.

This section describes the 2011 status of arterial operational functions within the MAG Region as they relate to traffic signal timing and operations, as well as current strategies for sharing information, and in some cases, sharing device control among agencies.


Traffic Signal Operations

Traffic signals represent the single largest arterial management and operations strategy in use by agencies in the MAG Region. Effective signal operations, including traffic signal timing and coordination, are among the highest priority for operational functions of traffic management agencies. Many traffic signals within the MAG Region are equipped with additional capabilities to support operations, including emergency vehicle preemption, and detection to support more traffic-responsive operations. There are a limited number of traffic signals currently equipped with priority capability for transit or light rail, but that capability is expected to increase with continued expansion of light rail routes throughout the Region in the coming years.

Number of Traffic Signals With Additional ITS Components and % of Total Signals Owned
Emergency Vehicle PreemptionPreemption EncryptionTransit PriorityLight Rail PriorityIn-Pavement DetectionVehicle Image DetectionMicrowave Detection
Total13477311401528686528
% of
Total
Signals
Owned
45%24%5%5%29%22%0%

Agencies that Operate Signals That Are Owned by Another Agency
OperateOtherSignals

Traffic Signal Timing

MAG has implemented a Traffic Signal Optimization Program (TSOP) that provides funding for local agency corridor traffic signal timing and coordination activities. Agencies in the Region submit candidate corridors for signal timing improvements, and the MAG ITS Committee reviews these requests and selects the corridors that will be funded. Other activities that have been funded as part of TSOP include data collection, Synchro model building, and Synchro training. Beginning in 2012, MAG will require before and after evaluations for corridor retiming projects that are funded by TSOP. Multi-agency applications for major corridors that impact more than one jurisdiction are encouraged. MAG does not guarantee funding for TSOP from year to year, but typical funding levels are between $280,000 and $400,000 based on available funding. Below is a historical view of the funding levels and number of intersections that were affected by TSOP projects over the last several years. Some projects have resulted in the development of computer models that are required for agency staff to identify and implement improvements.

YearAmountNumber of Intersections
2003-2004$298,589.9188
2007-2008$283,423.2991
2009-2010$283,518.72753
2010-2011$304,648.05697
2011-2012$405,500.00476

Traffic management agencies in the MAG Region are responsible not only for operating signals, but for operating them in a manner that improves overall progression and reduces delay on the arterial network. Traffic signal timing strategies vary by agency and those agencies that reported using a traffic signal timing strategy do not necessarily dismiss the importance of or exclude the use of other strategy types.

  • A majority of the agencies in the Region utilize coordination by time-of-day or by an actuated uncoordinated operational approach for their traffic signals. Agencies reported that they typically use a combination of traffic signal operational approaches for their signals.
  • Very few agencies are currently using traffic-responsive or adaptive signal operations strategies, but MAG is initiating discussions at the Regional level about the potential for this strategy in the future.
  • Most agencies update their traffic signal timing based on needs, such as changes in volumes on certain corridors or to accommodate specific events or activities such as work zones. In terms of more global updates, some agencies review and update traffic signal timing on a three to five year schedule.
  • Agencies use a variety of tools to support updates to their signal timing. Simulation software (such as Synchro) and turning movement counts are the most popular tools in use in the MAG Region, followed by 24 hour traffic counts (mainline volumes) and CCTV monitoring. CCTV is typically used to make more immediate adjustments based on conditions such as incidents or events that cause increased traffic demand.
  • More than half of the agencies in the Region indicated they implement special timing plans for work zones, and 67% indicate they implement special event timing plans.
  • There has been an increased focus on coordinating traffic signal timing and signal operations on cross-jurisdictional corridors, and more than half of the agencies in the Region indicate they coordinate with neighboring jurisdictions on traffic signal timing plans and strategies.
Traffic Signal Timing Strategies
TimingHowToSet

Traffic Signal Operational Approaches
TimingOpApproaches

Frequency of Updates to Traffic Signal Timing
TimingUpdateFreq

Procedures or Inputs to Update Traffic Signal Timing
TimingUpdateProcedures

Use of Special Timing Plans

Work Zones
SpecialTimingWorkZones
Special Events
SpecialTimingEvents


Coordinated Timing Plans with Neighboring Jurisdictions
CoordTimingNeighboring

Are Traffic Signal Timing Plans Developed In-House or Outsourced?
TimingInHouse

Agency Use of Left-Turn Approaches
TimingLeadLag

Traveler Information

Many local traffic management agencies provide information to travelers about the status, events or incidents impacting the arterial network. Nearly all local agencies in the MAG Region provide some level of information through city web sites, such as current and upcoming construction, special events and traffic restrictions, or major road closures. More than half of agencies in the MAG Region provide information via an email alert, which is typically sent to an established distribution list of other agencies, the media and in some cases travelers who have subscribed.

Social media, including Twitter and Facebook, are rising in popularity as a means of providing updated information about road construction projects or incidents. Twitter in particular, which is designed to disseminate brief updates, is used for alerts or incident notifications.

More than half of agencies in the MAG Region indicated that fixed and portable DMS are used to support traveler information. Some agencies also provide their information to the Arizona DOT for inclusion in the AZ511 system.

Arterial Traveler Information
TravelerInfo

How Agencies in the MAG Region are Using Arterial DMS
Usage# of Responses% of Total Responses
Travel Times3 20 %
Incident Information8 53 %
Construction / Work Zone Information11 73 %
Emergency / Threat Alerts7 47 %
Special Event Information11 73 %
AMBER Alerts5 33 %

TMC Functionality

Agencies Considering Sharing TMC Functionality with Neighboring Jurisdictions
Sharing Devices Control/Operations
SharingDevices


Sharing Facility Space
SharingFacilities
Sharing Internally with Another Department
SharingInternally

Use of Web-Based Traffic Maps by TMC Operators
WebTrafficMaps

Regional Connectivity

The institutional partnerships that have been established for many years in the MAG Region have created a number of regional systems that are being used for collaboration on cross-jursidictional corridors and real-time condition reporting on those corridors. There are advancements being made in each of the regional systems designated in the graph below that will provide additional functionality.

Agencies Using Regional Systems
RegionalConnectivity