ITS ePrimer Presentation
Module 4: Traffic Operations
(Note: The following PowerPoint presentation is a supplement to the module.)
Slide 1: ITS ePrimer Module 4: Traffic Operations
Intelligent Transportation Systems Joint Program Office Research and Innovative Technology Administration, USDOT
Author Notes for Slide 1:
The slides in this module are in this order:
- Learning Objectives
- Content-related slides
- Summary (what we have learned)
This module is sponsored by the U.S. Department of Transportation's ITS Professional Capacity Building (PCB) Program. The ITS PCB Program is part of the Research and Innovative Technology Administration's ITS Joint Program Office.
Thank you for participating and we hope you find this module helpful.
Slide 2: Instructor
Charles E. Wallace, Ph.D., P.E.
Alachua, FL, USA
Slide 3: Learning Objectives
- How ITS is used by agencies to operate the system
- Why form/maintain partnerships and how this is supported by ITS
- Why prioritize the options for applying ITS
- Recognize the role of management and operations (M&O) and how ITS can contribute to an overall Transportation Systems Management and Operations (TSM&O) mindset
- How to develop performance management goals
Author Notes for Slide 3:
- Understand how ITS technologies and applications are used by agencies to effectively operate the transportation system.
- Be energized to form and maintain relationships with other disciplines and jurisdictions within your region to ensure integrated traffic management across modes and stakeholder groups, and learn how ITS supports and facilitates the relationships between agencies, operators, and other partners to further operations objectives.
- Understand the importance of converting raw data into useful information to provide situational awareness to decision makers.
- Recognize that management and operation (M&O) of traffic is a primary goal of an organization, not simply building, operating, and maintaining infrastructure, and how ITS can contribute to an overall TSM&O mindset. This includes discussion of key elements:
- Traffic incident management
- Emergency management
- ITS maintenance
- Work zones
- Be able to develop performance goals that lead to improved traffic operations.
Slide 4: Traffic Operations - Introduction
Background - State/Rural Highways
Traditional transportation agencies' priorities:
- Building roads, bridges, tunnels, etc.
- Maintaining the infrastructure
These are generally run by state and county agencies
Author Notes for Slide 4:
Key Message: For many years these were the primary concerns of State Highway Departments and rural counties.
Most agency performance measures (if they had them at all) related to yards of asphalt and/or concrete laid, miles of roads repaired, etc.
Audience Interaction: Ask the class for others examples. Some possibilities:
- Safety improvements
- Repairing crash damage
- Some were toll roads, so collection of fees
Slide 5: Introduction (cont'd)
Background - Urban Highways and Streets
Traditional urban agencies' priorities:
- Building and maintaining streets
- Installing traffic control devices
- Operating traffic signals, and some coordinated systems These are generally run by cities and urbanized counties.
Author Notes for Slide 5:
Key Message: Traffic operations had an earlier start in urban areas because of the need to separate opposing traffic in time, since they usually couldn't do so in space.
We begin to see the institutional differences now: state/county versus city.
It should be noted that some states operate all traffic signals, but most operate none, or few. In the latter cases, the states usually install the signals, but a local agency operates them under an operate and maintain agreement.
Audience Interaction: Again, ask for some other examples:
- Cleaning the streets
- Parking control
Slide 6: Introduction (cont'd)
Emergence on urban freeways:
- Proactive traffic control
- Lane controls
- Safety service patrols
- Some ramp metering
- Traffic/Transportation Management Centers (TMCs)
McConnell Public Safety and Transportation Operations Center, Fairfax, VA
Source: Virginia DOT. http://www.virginiadot.org/travel/smart-traffic-center-nova.asp
Author Notes for Slide 6:
Key Message: As urban freeways became more prevalent in the latter half of the 1900s, agencies began to be more involved in traffic management, thus traffic operations.
The slide has several of the early treatments listed:
- Early use of closed-circuit television (CCTV)
- Xs and arrows (lane controls)
- Police or dedicated safety service patrols (SSPs)
- Ramp metering began in the 1960s
Eventually agencies needed a coordinated center to be the hub of traffic control.
TMCs are also called Traffic Operations Centers, or TOCs. The acronym TMCs will be used for consistency in this module.
Slide 7: Introduction (cont'd)
Arterial signal systems:
- Proactive traffic control
- Coordinated corridors
- Grid network control
- Traffic Control Centers (TCCs)
Source: ITS Florida, "ITS Awareness Seminar," developed by ITS Florida.
Author Notes for Slide 7:
Key Message: As urban arterial systems became more advanced, agencies began to be more involved in arterial traffic management, and traffic operations in general.
Surveillance early on was primarily detector data from intersections with some mid-block "system" sensors, so it was basically flow data, although some systems were more sophisticated. Now, closed-circuit television (CCTV) is becoming common.
Signal timing has been primarily accomplished by off-line optimization programs to develop time-of-day and other types of timing plans.
In coordinated corridors, they attempt to progress platoons of traffic.
In grid systems, like a downtown, they try to minimize some combination of delay and stops throughout the network.
Real-time traffic-adaptive control (RT-TRAC) is self optimizing and is just now becoming more common.
Eventually these agencies also needed a coordinated center to be the hub of traffic control. TCCs are increasingly becoming as functional as TMCs with the addition of more ITS.
Slide 8: Introduction (cont'd)
A Solution - Intelligent Transportation Systems (ITS)
(Extended Text Description: This graphic is a pie chart representing the Causes of Traffic Congestion from a FHWA Report. Segments are colored from pale blue and green, medium blue and green, and dark blue and green. Beginning at the top of the graph, moving in a clockwise direction, the pie wedge segments are identified as followed: pale green - Poor Signal Timing 5%, pale blue - Special Events/Others 5%, medium green - Work Zones 10%, Medium blue - Bad Weather 15%, dark green - Traffic Incidents 25%, and dark blue - Bottlenecks 40%.)
Source: "Traffic Congestion and Reliability: Trends and Advanced Strategies for 2547 Congestion Mitigation." Prepared for Federal Highway Administration (FHWA) 2548 by Cambridge Systematics, Inc., Cambridge, MA, September 2005.
Author Notes for Slide 8:
Key Message: On all roadways, albeit to different extents, the leading cause of non-recurring congestion is traffic incidents, as stated in the graphic.
Most of the other sources can be mitigated by ITS as well.
We will see that ITS technologies and processes are essential to effective traffic operations.
This begins with a discussion of the need for regional partnerships to follow.
Slide 9: Regional Operations Coordination
Highways Cross Jurisdictional Boundaries
- Multiple agencies/disciplines within jurisdictions
- Public safety, etc.
- Multiple jurisdictions
Regional Transportation Systems Management and Operations (RTSMO)
Author Notes for Slide 9:
Key Message: Transportation facilities are not isolated, either functionally or geographically. Users don't care who operates which facilities and systems; they just want them all to operate efficiently.
Today we need RTSMOs to effectively manage the system.
Ideally, formal organizations would be created to make this happen.
Audience Interaction: Ask if anyone is aware of such an organization in their area and, if so, to describe it.
Slide 10: Transportation Planning
Traditional transportation planning is a fairly rigid process
- Departments of Transportation (DOTs)
- Metropolitan Planning Organizations (MPOs)
- Cities and counties
- Other interested stakeholders
- User groups
Author Notes for Slide 10:
Key Message: In the past, the formal process for transportation planning was always focused on infrastructure.
The primary organizations are shown on the slide. The process is largely dictated by Federal rules, and states have adopted the same process for state planning.
At the purely local level, the process is similar, but may be less involved.
The context for planning is shown on the next slide.
Slide 11: ITS Project Life Cycle
(Extended Text Description: This is a flowchart representing the typical life cycle of transportation projects. At the top of the graphic is a dark blue rectangle with the title "ITS Strategic or Master Plan". Underneath the rectangle is a second rectangle with the text "System Architecture." Below the dark blue rectangles are six boxes with arrows to represent the stages of the transportation project life cycle. They are organized in two rows. Three boxes on the top, and three boxes on the bottom. Starting in the top row on the left, is a light blue box labeled "Program" in white letters. The arrow on this box points right to the top middle box. This box is labeled "Plan" in white letters. The arrow from this box points to the top right box labeled "Design" in yellow letters. The arrow from this box points down to the lower right box labeled "Construct" in yellow letters. This arrow from this box points left to the lower middle box labeled "Operate" in yellow. The arrow on this box points left to the lower left box labeled "Maintain" in yellow. The arrow from this box then points up, back to the upper left box titled "Program", and the cycle begins again. For additional relevant information related to this diagram, please see the Author Notes below.)
Author Notes for Slide 11:
Key Message: The typical life cycle of transportation projects has six common stages, as follows:
- Programming is the process of taking goals and objectives from an over-arching plan, such as an agency's Strategic Plan to developing concepts for achieving those goals and objectives. It usually includes identifying funding sources and approximate costs.
- Planning is the formal process of moving the project(s) from the programming stage into an approved status with a budget and target schedule for implementation. This process is prescribed for all projects funded with Federal dollars, and most states use it for state-funded projects as well. Often the MPO in the region plays a major role, even for Federal/state-funded projects.
- Design is the detailed process of determining the specific plans and specifications that can be used for construction and includes final cost details.
- Construction is the process of building the project.
- Operation is the set of daily and seasonable tasks that keep the facility working as planned.
- Maintenance is the process of ensuring the good health of the facility so that it remains functional.
As shown, it is a circular process that feeds back into itself for improvements, enhancements, and adopting new technologies and materials.
For ITS projects, the overall process is similar, but another overarching requirement is the ITS System Architecture. There is a National ITS Systems Architecture, a Statewide Architecture, and (if Federal funds are used), a Regional Architecture. These define which ITS devices may be used in a project, to ensure compatibility among similar deployments.
The programming and planning stages are pretty much the same as any other project, but the remaining stages, shown in yellow, have a more detailed set of steps, referred to as the Systems Engineering Process (SEP).
This is because ITS projects involve a more complex set of elements than typical infrastructure projects, namely electronics and software.
Slide 12: Planning for Operations
As a result, planning for operations is becoming more common
- Regional transportation operations collaboration and coordination
- Management and operations
- Link regional operations and regional planning
Author Notes for Slide 12:
Key Message: According to FHWA (source: http://ops.fhwa.dot.gov/travel/plan2op.htm), "Planning for Operations" includes three important aspects:
- Regional transportation operations collaboration and coordination activity that facilitates Regional Transportation Systems Management and Operations.
- Management and operations considerations within the context of the ongoing regional transportation planning and investment process.
- The opportunities for linkage between regional operations collaboration and regional planning."
It should be noted that designing for operations is also an outgrowth of this change in culture.
Slide 13: Planning for Operations (cont'd)
Transportation Systems Management and Operations (TSM&O)
FHWA: "an integrated program to optimize the performance of existing multimodal infrastructure through implementation of systems, services, and projects to preserve capacity and improve the security, safety, and reliability of our transportation system."
Author Notes for Slide 13:
Key Message: TSM&O is the new culture that the traffic operations community is promoting. It is rapidly gathering steam as evidenced by the active existence of the AASHTO Subcommittee on Systems Operations and Management (SSOM) and the TRB Committee on Regional Transportation Systems Management and Operations (AHB10).
It is important to have a plan or set of plans to guide the entire TSM&O effort. Components of this should include at least the following:
- An ITS Strategic Plan
- A TSM&O Plan
- A Traffic Incident Management Plan
- An Emergency Operations Plan
- A Traffic Signal Management Plan
Slide 14: Planning for Operations (cont'd)
Examples of TSM&O:
- Traffic incident management
- Traveler information services
- Traffic signal and arterial management
- Transit priority systems
- Freight management
- Road weather management
Author Notes for Slide 14:
Key Message: The examples here are not unique to TSM&O, but the rationale for TSM&O is to draw multiple jurisdictions and disciplines together to coordinate these and other programs.
TSM&O is being actively used in Florida, Maryland, Washington State, and likely others.
Audience Interaction: Ask if anyone can suggest others. The most obvious is Integrated Corridor Management (ICM).
Slide 15: Planning for Operations (cont'd)
Institutional Capability Maturity Model (ICMM)
Objective, to enhance:
- Culture and leadership
- Organization and staffing
- Resource allocation for operations
(Extended Text Description: This is a flow diagram showing the Institutional Capability Maturity Model. Beginning at the lower left of the diagram is a square labeled "Level 1". Inside this box is the label "Current Architecture (Ad hoc)." From this box an arrow points diagonally to the right to a second box labeled "Level 2." Inside the "Level 2" box reads "Improved architecture (Rationalized)." From the Level 2 box, an arrow points diagonally to the right towards a third box labeled "Level 3". This box is labeled "Target architecture (Mainstreamed)." Above this row of boxes is a second row of boxes. Above the "Level 1, Current Architecture (Ad hoc)" box, is a box labeled "Informal opportunistic program" and "Transitioning process". From this box, a large arrow leads to the box above the "Level 2, Improved Architecture (Rationalized)" box and "Planned standardized programs" and "Formal Processes" is written inside. From this box is a large arrow that leads to the box above the Level 3 "Target architecture (Mainstreamed)" box and "Performance-driven, integrated program and processes" is written inside.)
Source: Lockwood, S., P. Tarnoff, J. O'Laughlin, and T. Thatchenkery, Guide to Improving Capability for Systems Operations and Management, Transportation Research Board, SHRP 2 Report S2-L06-RR-2, 2011. Courtesy of the Transportation Research Board of the National Academies.
Author Notes for Slide 15:
Key Message: ICMM is a recent addition to TSM&O. It was adapted from Carnegie Mellon University's Capability Maturity Model Integration (CMMI).
The goal is to develop (in this case) a traffic operations program that is not only effective, but predictable as well.
The full text of the objectives is to enhance:
- "Culture/leadership related to the level of understanding and potential leverage of SO&M, as reflected in values, mission, leadership, and related legal arrangements and strategy applications, and as demonstrated by leadership.
- Organization and staffing related to how structure aligns responsibilities and accountabilities vertically and horizontally, consistent with capabilities and incentives at the staff level.
- Resource allocation for operations and capital, and the degree of transparency and sustainability in relationship to program improvement.
- Partnerships in terms of degree of alignment and stability in objectives, procedures, roles, and relationships."
While relatively new, the existence of Strategic Highway Research Program (SHRP) 2 tools, should promote ICMM. It has begun being implemented in Florida.
Slide 16: TMC/TCC Operations Overview
What's the Difference?
- Generally cover freeway systems
- Generally operated by states or regional agencies
- Use the full array of ITS devices
- Often multimodal
- Generally cover arterial systems
- Generally operated by city or county agencies
- Control traffic signal systems
Author Notes for Slide 16:
Key Message: Now let's get to the meat of the topic.
Module 3 covered the various ITS field devices like sensors, CCTV, dynamic message signs (DMSs), ramp meters, highway advisory radio (HAR), and road weather information subsystems (RWIS). This module covers how these subsystems and software are used to manage traffic and respond to incidents and emergencies.
While there is much overlap between TMC/TOCs (Traffic/Transportation Management/Operations) Centers and TCCs (Traffic Control Centers), they are covered separately because today, they are generally distinctly different.
We note that TCCs are quickly beginning to use ITS more fully, but the institutional differences remain for the most part.
Audience Interaction: Does anyone know of cases where the State DOT's TMC also has local traffic engineers controlling signals?
Slide 17: TMC/TCC Operations (cont'd)
- Operate TMC software system
- Monitor CCTV cameras and sensors
- Provide condition status
- Dispatch safety service patrols
- Notify public safety dispatchers
- Collect system performance data
- Collect operational performance data
Author Notes for Slide 17:
Key Message: These are the "what they do" functions of a typical TMC.
Audience Interaction: Name other functions. Some possibilities:
- Coordinate with co-located agencies.
- Monitor Environmental Sensor Stations (ESSs).
Slide 18: TMC/TCC Operations (cont'd)
- Manage recurring congestion
- Detect, verify, and manage traffic incidents
- Encourage trip time/route changes during incidents
- Furnish data/info to other agencies, especially in emergencies
- Manage misinformation to the public
Author Notes for Slide 18:
Key Message: These are the "why they do it" functions of a typical TMC.
Module 4 of the ITS ePrimer has a lengthy table of specific functions and expected outcomes under various conditions.
Audience Interaction: What are some others?
Slide 19: TMC/TCC Operations (cont'd)
TMC Operations Keys
- Manage traffic via interagency, multiple disciplinary integration of the TMC and other agencies
- The 4-Cs:
Author Notes for Slide 19:
Key Message: Ideally, the TMC would be an integral part of a regional operations organization and/or traffic incident management (TIM) Team.
- Communication - being in close voice and data contact with the other agencies for data/info sharing.
- Cooperation - working together, not separately, in solving problems.
- Coordination - ensuring that all parties are fully informed of activities, resource needs, and allocations.
- Consensus - applying unified command in considering options and decision making.
Audience Interaction: What communications media should be used?
- Telephone and cell phone.
- Common radio frequencies and protocols.
- Internet (emails and Web sites).
- Shared data and video feeds, including computer-aided dispatch from public safety.
- Remote TMC workstations in other agencies.
- Ideally face-to-face via co-location.
Slide 20: TMC/TCC Operations (cont'd)
- Operate TCC (usually just signals) software system
- Monitor sensors, maybe CCTV
- Provide condition status (media, some ADMSs)
- Dispatch signal maintenance
- Notify public safety dispatchers
- Collect system performance data
- Collect some operational performance data
Author Notes for Slide 20:
Key Message: TCCs are similar, but have some differences from TMCs. Note: ADMS = arterial dynamic message sign. Audience Interaction: Name other functions. Some possibilities:
- Coordinate with co-located agencies.
- Parking management.
Slide 21: TMC/TCC Operations (cont'd)
- Manage signal network
- Switch timing plans in emergencies and special events
- Detect and verify traffic incidents (if CCTV)
- Furnish data/info to other agencies, especially in emergencies
Author Notes for Slide 21:
Key Message: These are the "why they do it" functions of a typical TCC.
The ePrimer has another lengthy table of specific functions and expected outcomes under various conditions.
Slide 22: TMC/TCC Operations (cont'd)
- Documentation - plan, instruct, guide
- Staffing - base on needs, not just slots
- Training - never ends, always more to learn and practice
Author Notes for Slide 22:
Key Message: Documentation covers ITS Architecture, Concepts of Operations, TMC/TCC Operations manuals, incident management plans, emergency plans, standard operating procedures (SOPs), job guides, etc.
Staffing should be based on a needs assessment that addresses what you are trying to accomplish and what skills are needed to meet those needs, obviously considering the equipment and software you have deployed.
Training includes self-study, classroom, online course and simulations, table-top exercises, field exercises, on-the-job training, etc.
Note that neither the module nor ePrimer module covers such issues as funding, staging, and the like.
Audience Interaction: Ask if there are others. Funding would be an obvious one.
Slide 23: System Monitoring
System Status and Health
- System reliability
Author Notes for Slide 23:
Key Message: System monitoring has two aspects: 1) monitoring the system for the purposes of traffic management, and 2) monitoring to assess the health of the system itself. This section deals with the later. The first is covered later in the performance management section.
Good traffic operations requires an effective and well-operating system. System and even individual component failures can be detrimental to operations. The details of the bullets are as follows:
- System reliability - helps to ensure system robustness and overall reliability.
- Efficiency - the TMC and field equipment are operating at or above specifications and performing their expected functions properly.
- Effectiveness - that the ITS is achieving its program goals and objectives from an operational perspective.
- Accountability - enables managers to be confident that the investment in the ITS is being nurtured and protected through proper operation the vast majority of the time, or contrarily, that problems exist that need to be addressed.
Audience Interaction: Ask if anyone can suggest others. Meeting the agency's mission could be one.
Slide 24: Congestion Management
What is Congestion?
Demand > Capacity = Congestion
- Reduce demand
- Increase/enhance capacity
(Extended Text Description: There are a series of five small photographs running horizontally along the bottom of this slide. Starting on the far left is a photograph of a line of cars backed up on highway entrance ramp, trying to merge onto the highway. The second photograph to the right shows cars stuck in traffic during a snowstorm. The third photo shows a highway message display that reads: "Congestion 495 West NS 650 to MD 97 All Lanes Open". The fourth image is of trucks parked at a shipping dock. And the final image on the right is of road construction workers building to the right of a line of construction barriers, working on an unpaved road.)
Author Notes for Slide 24:
Key Message: A simple law of (traffic) physics is that when traffic demand approaches the roadway capacity, the quality of service rapidly diminishes, and then when demand exceeds capacity, traffic flow breaks down completely.
Strategically, there are only two ways to avoid this congestion: 1) reduce the demand, or 2) increase or enhance—that is make better use of—the capacity of the roadway.
Slide 25: Congestion Management (cont'd)
Demand Reduction Strategies:
- Promote alternative travel modes
- Work times/location:
- Flex time
- Satellite offices
- Real-time Advanced Traveler Information Systems (ATIS) to encourage behavioral change
Author Notes for Slide 25:
Key Message: There are a number of programmatic strategies for reducing traffic demand by encouraging changes in traveler behavior. Some examples are as follows:
- Programs that promote alternative travel modes, such as using transit, ride sharing, and associated travel demand management (TDM) services, as well as encouraging non-motorized travel.
- Encouraging flexible work times, telecommuting, and the use of satellite work places.
- Real-time ATIS that encourages drivers to use alternate routes, change trip times, or effect other behavioral changes.
Slide 26: Congestion Management (cont'd)
Capacity Enhancement Strategies - Freeways
- Ramp metering
- Reversible or contraflow lanes
- Electronic toll collection (ETC)/open road tolling (ORT)
- Managed lanes
- Hard-running shoulders
- Work zone management
- Variable speed limits
Author Notes for Slide 26:
Key Message: The following strategies—most of which are called active traffic management (ATM)—can be applied to enhance or increase capacity and/or stabilize flow (which has a similar affect) on limited-access highways, as indicated:
- Metering traffic onto freeways - by spacing out the merging traffic, there is less queuing in the acceleration lane, and smoother merges, which permits more stable flow past the ramp and increases throughput. Often freeway mainline speeds are increased dramatically.
- Reversible lanes - having reversible or contraflow lanes permits otherwise unused capacity in the off-peak direction to be used in the peak direction of flow. This is a good use of existing roadway, and ITS facilitates its operation through lane control signals, remote-controlled gates, CCTV, and sensors.
- Movable median barriers to add capacity during peak periods - functionally, this is similar to contraflow, but instead of shifting traffic to the other side of a median, the median itself is moved, effectively adding a lane to the peak direction.
- Automated toll collection improvements - electronic toll collection (ETC) is the standard for toll systems. "Open road tolling (ORT)" (or "free-flow tolling") have no cash collection at all.
- Managed lanes - are either new lanes or existing high-occupancy vehicle (HOV) lanes converted to high-occupancy toll (HOT) lanes that operate as toll lanes using ETC (or even ORT) for single-occupant vehicles (SOVs) or even low-occupant vehicles. Carpools of two- or three-plus occupants may generally use the HOT lanes freely (thus encouraging demand shift to HOVs), while SOVs are charged a variable toll that is dependent on the time of day, level of congestion in the general-use lanes, and occupancy of the HOT lanes.
- Hard-running shoulder - some locales allow buses and, in some cases, general (mixed) traffic to use the shoulder lane during peak periods. The name comes from the fact that the shoulders have to be upgraded to normal travel lane strength for "hard-running" traffic.
- Work zone management - work zones are clearly areas of reduced capacity. Efficient management of these areas is essential for efficient traffic operations, as discussed in greater detail later in this module.
- Variable speed limits - an element of ATM, using variable speed limits that better reflect the realistic speeds indicated by the onset of congestion can have calming effect and reduce erratic lane changing; thus the smoother traffic flow permits more throughput.
Slide 27: Congestion Management (cont'd)
Capacity Enhancement Strategies - Arterials
- Optimize signal timing
- Real-time traffic-adaptive control (RT-TRAC)
- Turn restrictions
- Reversible lanes on arteries
- Transit signal priority
- Signal timing for crossings
Author Notes for Slide 27:
Key Message: More strategies, these are focused on surface streets:
- Optimizing the timing of traffic signals - this strategy has been used nationally for many years; however, many cities and counties are somewhat lax in updating the timing to accommodate changing demand patterns.
- Real-time traffic-adaptive control (RT-TRAC) strategies eliminate the retiming issue altogether and can be even more effective, since they adjust cycle by cycle in near real time.
- Restricting turns at key intersections - this strategy eliminates signal phases (usually left turns) that take time away from the primary through movements.
- Reversible lanes - just as on freeways, some cities use reversible lanes on arteries for the same reason.
- Transit signal priority - this uses sensors and/or transponders to detect buses approaching an intersection and special control software to either extend the green time on the bus's phase if already green, or to shift the green to the bus phase from opposing phases.
- Signal timing for crossings - too often when trains, drawbridges, or other modes preempt signals and block traffic, signal timing continues as if the blockage had not occurred. Signal timings should be adjusted to accommodate re-routing that some drivers decide to do. Again, RT-TRAC strategies can react to this situation automatically.
Slide 28: Congestion Management (cont'd)
TMC-Specific Congestion Management Strategies
- Maximize use of ATIS
- Anticipate problemslook for signs
- Prioritize maintenance
- Use integrated corridor management (ICM)
- Use modeling tools
Author Notes for Slide 28:
Key Message: TMCs (and TCCs) are directly or indirectly involved in most of the foregoing strategies to some extent. What can TMC managers and operators do to explicitly help mitigate non-recurring congestion? Here are some examples:
- Use Advanced Traveler Information Systems (ATIS) to the fullest extent. TMC managers and operators can use their ATIS tools to maximize the dissemination of useful traveler information by all channels, particularly the DMSs, 511, HAR (if used), and media.
- Continuously scan the CCTV images looking for signs of breakdown, such as a smoking vehicle that might break down, debris on the roadway, dangerous or excessive vehicular maneuvers, or anything that might lead to an incident.
- Agencies might consider having the operations needs, not the order of occurrence, dictate the priority of both preventive and, even more importantly, reactive maintenance.
- Integrated Corridor Management (ICM) is designed to operate the freeways and arterial network, at least for a corridor with similar travel routes, to optimize the use of both types of facility.
- Finally, data being generated by ITS field devices and vehicle probes are valuable resources that may provide a foundation for the increasing use of models that can predict congestion and/or travel times to enable system managers and operators to take action to avoid the onset of congestion—either by diversion or trip changes. In the future, dynamic traffic assignment should become a reality.
Slide 29: Congestion Management (cont'd)
Capacity Enhancement Strategies
Need for ICM:
- Information sharing and coordination
- Optimization of the demand
- Informative decision making process
- Disseminate traveler information
- Analysis/prediction of system performance
- Estimation of traveler behavior
Author Notes for Slide 29:
Key Message: The purpose of ICM is to manage individual transportation corridor components, such as modes and facilities, which can be much more effective if accomplished in a coordinated and integrated manner. Following is a summary of the identified high-level needs:
- Information sharing and coordination across different transportation systems
- Optimization of the supply (available capacity of various modes and facilities) and demands for transportation services within the corridor
- Need for informative decision making process to assist in ICM implementation
- Need to disseminate traveler information that affects traveler's route, mode, and travel time decisions
- Analysis and prediction of system performance for planning and real-time operations
- Estimation of the behavior of travelers in response to advanced management strategies
Slide 30: Advanced Traveler Information
- Pre-trip information trip change
- En route information diversion or more caution
- Managed lanes time toll or money toll
- Long-distance info trip change
- Alerts public safety
Author Notes for Slide 30:
Key Message: Advanced Traveler Information Systems (ATIS) are used to inform travelers in the best possible manner to enable them to make informed—and hopefully safe—decisions about mode use, route taken, departure time, or even trip deferral. A side effect of these better decisions can often be supportive of efficient and safe traffic operations. For example, in the highway sector:
- Provide pre-trip information [such as via radio and TV traffic reports, Web sites, navigation maps, and information service provider (ISP) feeds] that might enable travelers to change their travel mode, change the trip departure time, or change the route of the trip, all to avoid an incident or just normal congestion, thus reducing traffic demand in the affected area.
- Provide en route information [such as via DMSs, radio traffic reports, GPS (global-positioning system) navigation maps, and ISP feeds to a smartphone] that might enable travelers to change their trip plans en route, such as changing their route or even abandon the trip, again, to avoid an incident or just normal congestion. Even if the traveler does not change any trip plans, just knowing the nature of congestion, perhaps with some indication of travel time or incident location, can reduce drivers' frustration and anxiety, thus making them safer drivers that are less prone to take unnecessary chances, such as excessive lane changing.
- On managed lanes, the current HOT pricing is conveyed by DMSs, allowing SOV
- drivers to make a decision to use the HOT lanes, thus relieving demand in the general-use lanes.
- Provide en route information during longer (e.g., intercity or interstate) trips, using techniques like those mentioned previously (as applicable) or kiosks at rest areas, to help these longer range travelers adjust their trip plans.
- ATIS can also provide information that does not directly affect current travel, but serves other purposes, such as safety messages, smog alerts, and for AMBER and Silver Alerts. Silver Alerts are modeled after AMBER (America's Missing: Broadcast Emergency Response Alerts), but are for senior citizens suffering from irreversible deterioration of intellectual faculties and are believed to be missing. These alerts are used in many states, but are often called by different names.
Slide 31: Road Weather Information Systems (RWIS)
What They Do
RWIS uses Environmental Sensor Stations (ESSs) to measure:
- Air temperature
- Roadway temperature
- Wind velocity
- Falling or suspended materials
- Fuel emissions
(Extended Text Description: This is a photo of an Environmental Sensor Station. The station is a tall white metal pole with electronic attachments mounted on a cross bar on the top of the pole. There is another device attached to the pole two-thirds of the way down from the top, as well as electronic boxes at the base of the pole. The pole sits on a grass field next to the water.)
Author Notes for Slide 31:
Key Message: To review from module 3, a Road Weather Information System (RWIS) consists of a set of sensors, or Environmental Sensor Stations (ESSs), that can detect and report a number of environmental measures that affect roadway operations. Depending on the particular ones desired, these can include the following:
- Ambient air temperature.
- Road surface temperature.
- Wind direction and speed.
- Presence of falling or suspended particulates, such as dust, rain, snow, sleet, smoke, and fog.
- Fossil fuel emissions (technically not road weather information, but in the family).
Slide 32: RWIS (cont'd)
- Snow and ice mitigation
- Detect hazardous environmental conditions
- Detect visibility hazards
- Assist in bridge closing
- Policy for signal timing
- Commercial weather services
Author Notes for Slide 32:
Key Message: RWIS is an effective tool for traffic (and agency operational) management. Some uses are as follows:
- Optimize maintenance operations in cold climates and/or mountainous regions where snow and ice are commonplace by enabling mangers to dispatch the right equipment and materials at the right times.
- Detect conditions that may be hazards (such as high winds or flooding) that impact roadway operations.
- Detect other conditions that cause reduced visibility, such as fog, smoke, blowing dust or sand, and blizzard (white-out) conditions on roadways. Note that smoke and fog together make a particularly hazardous combination, as experienced on I-4 and I-75 in Florida in 2008 and 2012, respectively.
- Wind-speed sensors on some roadways and on bridges alert TMCs when they should consider issuing travel advisories for trucks and other large vehicles. When winds are particularly high, they may indicate the need to close bridges to all traffic.
- Environmental sensors can be used as a policy for RT-TRAC signal control.
Several of these measures have the primary purpose to assist the agency in being more efficient, but better traffic operations is a welcome spin-off.
A number of DOTs (as well as other industries) subscribe to commercial weather forecasting companies that provide timely, location-specific forecasts that are reputedly even better than the National Weather Service. This is possible because they draw their data from multiple sources, including the National Weather Service, and fuse the results.
Slide 33: Traffic Incident Management (TIM)
Stages of an Incident
(Extended Text Description: The graphic on this slide illustrates the time line of a traffic incident. The graph is shaped in a rectangle made up of three sections. Beginning on the far left in the gray area, are steps A and B of the timeline. A: Incident Occurs. B: Initial Notification. To the right of this section is a dark blue square section titled "Incident Duration." Beginning in the upper left corner of this section are steps C-M are arranged going diagonally down the square from the upper left to the lower right. C-M read as follows: C: Incident Verified, D: Responder dispatch, E: Responder arrives, F: Responder summons help, G: Required help arrives, H: Summon wrecker, I: Wrecker arrives, J: Other help leaves, K: Wrecker clears the lanes, L: Wrecker leaves site, M: Law enforcement leaves site. Surrounding the dark blue section is a light blue section labeled "Incident Influence Time." In this section, written just below step M in the dark blue section reads "Normal traffic flow." For additional relevant information on this graph, please see the Author Notes below.)
Source: Wallace, C.E., J. O'Laughlin, and T. Smith, Toolkit for Deploying TIM/QC Best Practices. Prepared for the I-95 Corridor Coalition, Telvent Farradyne, 2007, updated 2009.
Author Notes for Slide 33:
Key Message: As shown earlier, traffic incidents are the leading cause of non-recurring congestion. To fully understand how incidents are managed, one must understand the time line, or stages, of an incident, which can be summarized as follows:
- Detection that an incident has occurred.
- Verification that the incident has indeed occurred, determining its location, and having sufficient information to enable an appropriate response.
- Response by dispatching appropriate assets to resolve the incident.
- Clearance, or the removal of the vehicles, damaged property, and victims, first from the roadway itself and complete reopening of any blocked lanes, and then from the entire incident scene.
- Recovery to normal traffic flow.
This graphic illustrates the time line. Notice that recovery is relatively longer than the earlier stages. Incident managers estimate that recovery normally takes four to five times longer than the combined earlier stages (starting with verification).
Thus every minute saved in these earlier steps, particularly clearance, which is generally the longest of these, saves 4-5 minutes in recovery.
That is critical to efficient traffic operations, and reduces the chances of secondary incidents, which just restart the cycle all over again.
Secondary incidents are often more severe than the original incident.
Audience Interaction: Notice that we refer to secondary incidents, not crashes. Can you name some other typical secondary incidents?
- Vehicles run out of gas idling in the queue
- The overheat and stall
- Drivers turn off their engines and can't restart
- Road rage results in confrontations
- Drivers make erratic maneuvers to try to exit the roadway or bypass the incident and crash and hit guardrails
Slide 34: TIM (cont'd)
Traffic Incident Management Teams
- Federal agencies
- State DOTs (TIM group)
- Law enforcement (state and local)
- Fire and emergency medical services (EMS)
- Others involved in public safety
Author Notes for Slide 34:
Key Message: Many regions have found it useful to form an interagency, multijurisdictional TIM team.
The team can operate as a unit to create TIM Plans and Concepts of Operations (ConOps) that identify stakeholders and their respective roles and responsibilities in incident management, and then continue to function as a mechanism for sharing new techniques, cross-training, and conducting post-incident assessments through regular meetings.
Members of the TIM team can, and generally should to the extent practical, come from all of the stakeholder groups listed on the slide.
Some, such as Federal agencies, may serve more of an advisory role than an active role in TIM.
TIM teams, while not an absolute requirement, can greatly enhance the effectiveness of incident response and recovery, thus improving traffic operations.
One of the important things TIM teams can do is to promote an "Open Roads Philosophy," under which agencies agree on a formal "Open Roads Policy (ORP)" to clear the roadway as quickly as safely possible. Some even set a numerical goal, usually 90 minutes following the arrival of the first responder.
Audience Interaction: Name some of the others. Possibilities are:
- Towing and recovery
- HAZMAT services
Slide 35: TIM (cont'd)
ITS Role in the Stages of TIM:
- Sensors - incident detection algorithms
- CCTV - operators detect, verify, and monitor
- DMSs/HAR - alert road users to incidents
- 511/media - alert potential users
- Data and videos - after-action analysis and training
- TMC - a hub for TIM
Author Notes for Slide 35:
Key Message: Now we turn more explicitly to the roles that ITS plays in TIM.
Module 4 of the ITS ePrimer contains a table that details the various functions of ITS for each stage of an incident. Here, we briefly summarize the functions from the perspective of ITS devices and the TMC:
- Some TMC software systems have automated incident detection algorithms that track traffic characteristics (e.g., volume, speed, etc.) over time and location to detect significant changes in traffic flow patterns to insinuate an incident. An alert is issued so an operator can follow up and confirm an incident.
- TMC operators use CCTV cameras to detect incidents themselves, verify incidents reported by others, and monitor the response, clearance, and recovery, reporting changing conditions and status as needed.
- DMSs, and HAR, if available, are used to inform users that are actually traveling on the highway, or approaching the highway, of the incident.
- 511 and the media are used to inform the general public, so they can possibly change their trip plans.
- Archived data and recorded CCTV images (if the agency allows this) can be used for post-incident analysis and training.
- The TMC itself is a (note "a", not "the") hub for managing the incident. The official hub is the on-scene incident commander and his/her unified command, but the TMC is a valuable resource for assisting in the incident management.
All of these tools dramatically impact traffic operations for the better—reducing incident durations and lessening the chance of secondary incidents.
Slide 36: Emergency Transportation Operations (ETO)
Incident Frequency vs. Severity:
(Extended Text Description: This graphic illustrates the declining frequency of incidents of various types and the agencies involved as the severity increases. Starting from the upper left corner of the slide are a series of gray boxes representing types of incidents. To the right of each gray box is text highlighting who is impacted by each type of event. From the upper left, the first gray box is labeled "Planned Events." The text next to the box is "Public Safety." Coming from the lower side of the gray box is an L-shaped arrow pointing right to the second gray box labeled "Minor Incident." Next to the box is the text "DOTs, State & Local Agencies." From the bottom of the gray box, an L-shaped arrow points to the third gray box labeled "Major Incident." Text next to it reads "More Locals." From the bottom of the third gray box is an L-shaped arrow pointing to the fourth gray box below labeled "HAZMAT Event." Next to this box reads "Emergency Managers." From the fourth gray box, an L-shaped arrow points to the fifth gray box labeled "Natural Disaster." The text next to this box reads "State Emergency Managers/Feds." From the bottom of the fifth gray box is an L-shaped arrow pointing to the final sixth gray box labeled "Terrorist Incident." Next to this box is the text "Many Feds." Drawn in between the "HAZMAT Event" and "Natural Disaster" is a blue line arc that runs from the bottom left corner of the slide and gradually increases all the way to the upper right corner. This line is labeled "Severity." For additional relevant information regarding this diagram, please see the Author Notes below.)
Author Notes for Slide 36:
Key Message: Now we move from "typical" traffic incidents to more serious incidents, which we refer to as emergencies, since they are more severe in nature.
Emergency transportation operations (ETO) brings in a somewhat different cast of players to respond to and manage these events. This section addresses the characteristics and responses to emergency events where little or no advance notice is provided, as well as for events with more advanced notice but with largely unpredictable impacts (such as a hurricane).
This graphic illustrates the declining frequency of incidents of various types and the types of agencies involved as the severity increases.
Following 9/11/2001, a number of national initiatives were implemented to improve our emergency preparedness and response. One of the most important to transportation agencies was the National Incident Management System (NIMS). (It should be noted that all incidents, even minor traffic crashes, are subject to NIMS albeit, usually on an informal basis.)
Slide 37: Maintenance Operations
ITS System Maintenance
A well-maintained system helps traffic operations
Maintenance management systems ensure:
- Maintainability of various components - many vendors
- Consistent policies and practices
- Inventory control
- Work-order management
- Expense tracking
Author Notes for Slide 37:
Key Message: Maintenance of ITS devices and traffic signal systems can clearly impact traffic operations. There are two aspects related to operations.
The first relates to physical device maintenance, namely, monitoring device operational status, scheduling preventive maintenance, and monitoring operational performance. Included are discussions of maintenance management systems, and such specialized support systems as fiber management systems.
The second aspect relates to maintenance activities on the roadway and its impact on traffic. Because freeway management systems (FMS) and arterial management systems (AMS) are somewhat different, they are covered separately, while recognizing some commonality.
A well-designed maintenance management system is important because:
- The size and inventory is growing due to technological advances.
- ITS maintenance is different than roadway maintenance; it is mostly involving electronics and communications.
- The number of stakeholders involved is greater (e.g., manufacturers, vendors and suppliers, maintenance staff, sometimes from different agencies, etc).
- There are integration issues associated with many different device types and brands.
- There is a need for consistent procedures and practices.
- There is a need for accurate and complete ITS inventory (devices and materials, such as fiber).
- There is a need for an efficient work-order-based maintenance system.
- There is a need for the ability to track expenses (e.g., labor, materials, parts, entire devices, and MOT) to the specific device or subsystem.
- There is a need for timely, accurate, and comprehensive reporting.
- There is limited funding - need to be efficient and effective with available resources, while at the same time justifying the maintenance program.
Slide 38: Work Zones
ITS is useful for:
- Traffic monitoring and management
- Providing traveler information
- Incident management
- Enhancing safety of both the road user and worker
- Enhancing capacity
- Tracking data for performance-based contracting
- Work zone planning
Author Notes for Slide 38:
Key Message: By their very nature, work zones have a negative impact on traffic operations.
The purpose of using ITS (and other techniques) is to minimize the negative impacts and keep traffic moving through the zone as efficiently, and safely (for both the travelers and workers), as possible, especially for nighttime work.
ITS technology can be applied in work zones for the uses shown on the slide.
Slide 39: Performance Management
Performance management is important for:
- Meeting agency goals and objectives
- Resource allocation
- Providing positive road-user benefits
- Providing performance measures (PMs) that are consistent
- Providing PMs that are outcome-based
Author Notes for Slide 39:
Key Message: The need for performance measures (PMs) is widely recognized. Performance measures have been a topic of discussion for many years; however, it is only recently that ITS devices provided the data that are essential to supporting PMs and their importance in operations.
The current transportation authorization act, Moving Ahead for Progress in the 21st Century (MAP-21) created a new standard for performance- and outcome-based programs.
Performance management from the ITS industry's perspective is important to:
- Ensure that the agency achieves its goals and objectives.
- Ensure adequate resource allocation.
- Ensure that the systems deployed are cost-effective.
- Ensure that the return on investment is positive in terms of road-user benefits.
- Ensure that the performance measurements are consistent across the country.
- Ensure that the performance measurements are increasingly outcome-based, rather than simply output-based.
Slide 40: Performance Management (cont'd)
(Extended Text Description: This pyramid graphic illustrates the framework for using the indicated measures as part of performance measurement and management. The pyramid is divided into three stacked sections by two horizontal lines. The section at the base of the pyramid is titled "Programming Activities and Performance Measures" followed by the text "Inputs: resources required to accomplish an activity. Outputs: quantitative measures of what the activity produces. Outcomes: Impact of activity (quality, not just outputs). Efficiency: cost per unit of outputs and outcomes." Above this section is the mid-section of the pyramid titled "Indicators/Performance Targets" followed by the text "Measures of success toward accomplishing strategic objective." Above the mid-section is the top of the pyramid titled "Strategic Objective." Under this title, the text reads "Mission or vision." Along the left side of the pyramid are two bracket lines. The first bracketed line runs parallel to the side of the lower half of the pyramid and is titled "Performance Measurement." The second bracketed line runs parallel to the side of the upper half of the pyramid and is titled "Performance Management.")
Author Notes for Slide 40:
Key Message: This graphic illustrates the framework for using the indicated measures as part of performance measurement and management.
According to FHWA, the following four performance measures are being given emphasis:
- Travel-time reliability (Buffer Index) - the buffer index is the additional time that must be added to a trip, to ensure that travelers making the trip will arrive at their destination at, or before, the intended time, 95% of the time.
- Extent of congestion - spatial (also measurable by time) - miles of roadway within a predefined area and time period, for which average travel times are 30% longer than unconstrained travel times.
- Incident duration - the time elapsed from the notification of an incident until all evidence of the incident has been removed from the incident scene.
- Customer satisfaction - a qualitative measure of customers' opinions related to the roadway management and operations services provided in a specified region.
All of this is aimed at ensuring the best possible level of operational service to the traveling public.
Audience Interaction: Can anyone identify other PMs that would be useful that ITS can expressly help with (bearing in mind these are national PMs)?
- Total vehicular throughput
- Total person throughput
- Percentage on-time arrivals of transit vehicles
- Percentage on-time arrivals of commercial vehicles
Slide 41: Summary
Effective traffic operations leads to satisfied road users Priorities are:
- Environmentally sound
Author Notes for Slide 41:
Key Message: Hopefully this module has instilled a strong sense of passion for the importance of traffic operations. Highways and other modes are merely conveyances for vehicles, people, and cargo. How effectively these users of the transportation system maneuver through the system is—or should be—the primary business of transportation agencies and their partners. The priorities in this regard are the following:
- Safety - of both the traveling public and those who service the system in any way.
- Efficiency - for people and goods to complete their trips in a timely and cost-effective manner.
- Environmentally sound - minimize the use of fuel and other resources, while minimizing pollutants.
- Security - ensuring the welfare of transportation users and those affected by the traffic.
Key tenets of this effort are inter-agency/multijurisdictional exercising of the 4-Cs— communication, cooperation, coordination, and consensus—focusing on operations and not equipment per se; and viewing transportation users as customers, placing their satisfaction first.
Slide 42: Summary - Now You Should Know ...
- How ITS is used by agencies to operate the system
- Why it is important to form/maintain partnerships
- Why it is important to prioritize the options for applying ITS
- How to recognize the role of management and operations and how ITS can contribute to an overall Transportation Systems Management and Operations mindset
- How to develop performance management goals
Author Notes for Slide 42:
- We covered how ITS technologies and applications are used by agencies to effectively operate the transportation system.
- You should now understand the importance of relationships with other disciplines and jurisdictions within your region to ensure integrated traffic management across modes and stakeholder groups, and understand how ITS supports and facilitates the relationships between agencies, operators, and other partners to further operations objectives.
- You should appreciate that operations should be a priority in assessing the options for applying ITS technologies and applications.
- You should understand why management and operation (M&O) of traffic is a primary goal of an organization, not simply building, operating, and maintaining infrastructure and understand how ITS can contribute to an overall TSM&O mindset.
- You should be able to develop performance goals that lead to improved traffic operations and understand why they are important.
Slide 43: References
Author Notes for Slide 43:
Major references listed. The FHWA Office of Operations Web site has a treasure chest of information about traffic operations, planning for operations, TSM&O, various ITS subsystems, etc.
Slide 44: Questions?
- Maintaining roads and bridges is the most important job of transportation agencies: True or False?
- Are O&M and M&O just the same thing?
- What is the primary cause of recurring congestion?
- What is the primary cause of non-recurring congestion?
- Transportation planning has nothing to do with traffic operations: True or False?
- The primary job of a TMC is to focus on system status: True or False?
Author Notes for Slide 44:
- False; while maintenance is very important, operations is (or should be) the top priority.
- No, operation and maintenance is the old way of looking at this, management and operations (the latter including maintenance) is the right terminology.
- Bottlenecks that reduce capacity, such as major interchanges, heavy merging or weaving, grade changes, sharp curves, etc.
- Traffic incidents, the worst of which are crashes, but debris, stalls, and even roadside activities can cause them.
- This was somewhat true in the past, but planning for operations is now considered a priority.
- False; just like question 1, system up-time is important, but managing the traffic is the TMC's job one.
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