Active Traffic Management (ATM) Implementation and Operations Guide

CHAPTER 5. OPERATIONS AND MAINTENANCE

This chapter provides guidance on operations and maintenance issues agencies will face once active traffic management (ATM) strategies go online. The chapter includes the following sections:

• Activation Thresholds and Performance Monitoring. This section discusses activation thresholds related to ATM operations and how agencies might use data and performance monitoring during ATM strategy activation. It also discusses performance monitoring of ATM strategies that can support daily activation and operations.
• Performance Evaluation. This section discusses the issues associated with evaluating the performance of an ATM deployment, including how an agency collects data and analyzes it to quantify or justify the deployment of an entire system or to demonstrate to what extent the deployment meets intended regional mobility goals and objectives.
• Maintenance. This section highlights the importance of maintenance of ATM strategies and the elements of maintenance that are needed on a periodic basis.
• Incident Management. This section provides information on the importance of incident management on facilities with ATM strategies along with strategies, agreements, and agency collaboration that can facilitate that management.
• Enforcement. This section presents the issues related to enforcement of ATM strategies and the options agencies can consider when establishing enforcement policy and procedures.
• Costs. This section discusses the overall costs associated with operations and maintenance of ATM systems and strategies for budgeting and programming those operational costs throughout the life of the project.

5.1 ACTIVATION THRESHOLDS AND PERFORMANCE MONITORING

ATM involves dynamically applying and adjusting traffic management strategies in response to current, measured travel conditions; therefore, performance monitoring is a critical element of ATM. Performance monitoring is an ongoing internal process where system conditions and performance are examined and evaluated through data collected through devices/equipment installed in the field. Performance monitoring provides the data needed in the decision-making process. With performance monitoring, detection and monitoring systems are generally used to indicate the current operating state of the system and to identify potential operational problems and situations that need to be addressed by operators (e.g., traffic incidents). The active management cycle shown in Figure 29 demonstrates the relationship between ATM performance monitoring and the ongoing active management of an ATM system.

ATM projects are successful when they are actively managed. Ongoing monitoring of system conditions from devices and equipment provides data needed in the activation of strategies and the active management decision process.

Figure 29. Diagram. The Active Management cycle.⁽²⁸⁾

Recent research related to implementation thresholds and performance monitoring shed light on the trends related to ATM operations. Recent National Cooperative Highway Research Program (NCHRP) 03-114 efforts revealed that deployment agencies use data and performance monitoring during ATM strategy activation, and activations typically fall into one of two types of processes that vary greatly in the thresholds used.⁽⁸¹⁾ These systems are as follows:

• Automated systems are where data are automatically collected and applied to a set threshold to activate an ATM strategy. There are few fully automated systems to reference in determining appropriate thresholds for activation and deactivation. Speed and occupancy of mainline detection are typically the fundamental data sources for automated system alerting or decision making.
• Manual systems are where data are collected or visual confirmation is acquired and operators must manually make operational changes to their ATM applications. The processes are not automated other than potentially the data collection effort—analysis of the data is largely done manually. ATM strategies that have been deployed to support weather events and most shoulder use applications are manual systems that rely on an operator to verify activity prior to manually changing a sign display. The data most used by operators in manual ATM systems involve a combination of mainline detection of speeds and/or closed circuit television (CCTV) camera image monitoring.

Agencies may implement a hybrid of these two processes in which the system automatically generates a recommended activation but requires an operator to accept or confirm activation. Additionally, agencies may start with ATM strategies that are manually deployed and move along the active management continuum as experience, technology, and regional needs evolve. This evolutionary approach allows agencies to gain active management capability over time and gain experience with managing ATM strategies as part of their overall transportation systems management and operations (TSMO) approach. Table 16 shows that each ATM strategy can have a set of operational objectives and traffic parameters that deployment agencies can measure in real time to assess current operating conditions.

ATM systems can either be fully automated in deployment and operation, manual in nature where operators activate the strategy, or a hybrid of the two processes. Agency processes, procedures, and data are needed for successful operations.

Table 16. ATM strategies, data, and implementation processes.⁽⁸¹⁾

ATM Strategy	Operational Objectives and Traffic Parameters	ATM Strategy—Threshold	Data Set Required (at minimum)	Implementation Process
Adaptive Ramp Metering (ARM)	Maintain smooth flow of mainline and increase throughput while not backing up to arterial cross streets and minimizing wait times to get onto freeway.	Thresholds are typically a combination of occupancy of the mainline, volume of the mainline, queue length of the ramp, and/or storage length of the ramp. For larger ramp meter systems with many along a single corridor, an adaptive system that interprets ramps upstream and downstream of the detected thresholds is effective. For smaller ramp meter systems with only a few along a single corridor, an adaptive system that interprets the local ramp traffic characteristics should suffice.	Occupancy;speed; vehicle count (volume)	Automated
Dynamic Junction Control / Dynamic Merge Control (DJC/DMC)	Maintain smooth flow of mainline, reducing incidents due to merges and aggressive driver behavior.	Late merge applications should activate when occupancy >15% of the time but deactivate when occupancy <15%. Early merge applications should activate when occupancy is less than 5%. Traditional merge should be between 5%–15%.	Occupancy and/or speed	Automated
Dynamic Lane Reversal (DLR)	Allow existing capacity to better match traffic demand throughout the day.	DLR to be considered in instances of lane closures due to incidents of 1 hour or greater, with the threshold equal to twice the time it takes for the reversal to be activated. For example, if the reversal takes 1 hour, the reversal threshold should be at least 2 hours of closure time.	Major incident occurrence	Manual
Dynamic Lane Use Control (DLUC)	Reduce crashes and improve safety.	Operator controlled based on visual confirmation of lane closure or system alert to close a lane.	Incident alert	Manual
Dynamic Shoulder Lane (DShL)	Reduce vehicle density per lane and increase service volume capacity.	Speed should be monitored along the mainline to warrant use of shoulder lane to ease congestion. Operator should verify no obstruction in the shoulder lane prior to opening. Where speed is not available, time-of-day applications of this ATM strategy are effective and have been evaluated to be safe through proper signage and public education.	Speed of mainline detection	Manual—alerted by speed data Automated—alerted by time of day
Dynamic Speed Limit (DSpL)	Increase speed, maximize throughput, decrease congestion, reduce secondary incidents, and reduce speed variation near an incident or weather event.	Threshold is mainline vehicle speed at 85th percentile average speed, with speeds dropping under 50 mph for at least 3 minutes during the day or 5 minutes at night. Speed at detector location compared to downstream speed.	Speed and potentially occupancy	Automated
Queue Warning (QW)	Reduce rear-end crashes and improve safety.	Detecting lowered speed should automatically populate upstream message signs to alert agency of queue forming ahead.	Speed and potentially occupancy	Automated

Performance reporting for ATM deployments includes three general types: (a) real-time reports, (b) time period reports, and (c) planning and design reports. According to recent NCHRP efforts, when considering time period reports, agencies often use a combination of short-term and long-term reports. The short-term time period reports collect data to adjust real-time parameters, often daily or monthly. Long-term time period reports collect data to validate ATM strategies, usually on a quarterly or yearly basis.

Table 17 presents a summary of each ATM strategy and related performance reporting data, how frequently agencies might report those data, and in what forms. Additional information is provided to identify data requirements and recommended measures.

The prime focus of short-term performance monitoring is to evaluate the performance measures on a daily, weekly, or monthly basis and adjust the thresholds accordingly. This adjustment is based on the operational effect of the threshold in satisfying the ATM strategy objectives. In case of adverse effects, the threshold logic will be remodeled and implemented. This cycle will be continued until the desired outcome is achieved. In this instance, all the thresholds are determined by analyzing the historic trends of various traffic parameters.

The long-term performance monitoring particularly concentrates on evaluating the performance measures to ensure the accomplishment of operational objectives of the respective ATM strategy. This long-term monitoring is a foundational element of performance evaluation discussed in the following section. This evaluation considers multiple traffic parameters to depict network-level effect of the strategy. Necessary adjustments will be performed after thorough analysis of the data. It is important to note that the effectiveness of short-term and long-term performance monitoring depends on the quality of data collected. Therefore, detector health is a key factor for any evaluation or monitoring.

ATM performance monitoring and the data collected during these activities supports both daily operations, adaptive and dynamic changes, as well as longer-term performance evaluation.

Table 17. ATM strategy performance monitoring data requirements for threshold adjustments.⁽⁸¹⁾

ATM Strategy	Operational Objectives	Sample Agencies	Performance Measures for Time Period Reports	Data Required	Typical Measures
Adaptive Ramp Metering (ARM)	Maintain smooth flow of mainline and increase throughput while not backing up to arterial cross streets and minimizing wait times to get onto freeway.	WSDOT, Caltrans District 7, ODOT, MnDOT, VDOT, VicRoads	Throughput—vehicle	Vehicle counts	Short-term: review thresholds monthly based on daily throughput measures. Long-term: review thresholds quarterly or annually based on all measures to meet the operational objectives.
Adaptive Ramp Metering (ARM)	Maintain smooth flow of mainline and increase throughput while not backing up to arterial cross streets and minimizing wait times to get onto freeway.	WSDOT, Caltrans District 7, ODOT, MnDOT, VDOT, VicRoads	Throughput—person	Vehicle counts by facility and/or lane type	Short-term: review thresholds monthly based on daily throughput measures. Long-term: review thresholds quarterly or annually based on all measures to meet the operational objectives.
Adaptive Ramp Metering (ARM)	Maintain smooth flow of mainline and increase throughput while not backing up to arterial cross streets and minimizing wait times to get onto freeway.	WSDOT, Caltrans District 7, ODOT, MnDOT, VDOT, VicRoads	Vehicle miles of travel (VMT)	Vehicle counts; length of road	Short-term: review thresholds monthly based on daily throughput measures. Long-term: review thresholds quarterly or annually based on all measures to meet the operational objectives.
Adaptive Ramp Metering (ARM)	Maintain smooth flow of mainline and increase throughput while not backing up to arterial cross streets and minimizing wait times to get onto freeway.	WSDOT, Caltrans District 7, ODOT, MnDOT, VDOT, VicRoads	Travel time index	Actual travel rate; ideal travel rate	Short-term: review thresholds monthly based on daily throughput measures. Long-term: review thresholds quarterly or annually based on all measures to meet the operational objectives.
Adaptive Ramp Metering (ARM)	Maintain smooth flow of mainline and increase throughput while not backing up to arterial cross streets and minimizing wait times to get onto freeway.	WSDOT, Caltrans District 7, ODOT, MnDOT, VDOT, VicRoads	Overall crash rate	Total crashes; VMT	Short-term: review thresholds monthly based on daily throughput measures. Long-term: review thresholds quarterly or annually based on all measures to meet the operational objectives.
Dynamic Junction Control / Dynamic Merge Control (DJC/DMC)	Maintain smooth flow of mainline, reducing incidents due to merges and aggressive driver behavior.	WSDOT, Caltrans, MnDOT, Maryland SHA, Michigan Department of Transportation (MDOT)	Number of incidents by type and extent of blockage	Incident reports	Short-term: timely comparison of speed and delay trends to adjust thresholds. Long-term: comparative evaluation of VMT and crash reports on a quarterly and annual basis.
Dynamic Junction Control / Dynamic Merge Control (DJC/DMC)	Maintain smooth flow of mainline, reducing incidents due to merges and aggressive driver behavior.	WSDOT, Caltrans, MnDOT, Maryland SHA, Michigan Department of Transportation (MDOT)	Operating speed reliability	Speed data with respect to time	Short-term: timely comparison of speed and delay trends to adjust thresholds. Long-term: comparative evaluation of VMT and crash reports on a quarterly and annual basis.
Dynamic Junction Control / Dynamic Merge Control (DJC/DMC)	Maintain smooth flow of mainline, reducing incidents due to merges and aggressive driver behavior.	WSDOT, Caltrans, MnDOT, Maryland SHA, Michigan Department of Transportation (MDOT)	Congested travel	VMT; speed counts	Short-term: timely comparison of speed and delay trends to adjust thresholds. Long-term: comparative evaluation of VMT and crash reports on a quarterly and annual basis.
Dynamic Junction Control / Dynamic Merge Control (DJC/DMC)	Maintain smooth flow of mainline, reducing incidents due to merges and aggressive driver behavior.	WSDOT, Caltrans, MnDOT, Maryland SHA, Michigan Department of Transportation (MDOT)	Overall crash rate	Total crashes; VMT	Short-term: timely comparison of speed and delay trends to adjust thresholds. Long-term: comparative evaluation of VMT and crash reports on a quarterly and annual basis.
Dynamic Lane Reversal (DLR)	Allow existing capacity to better match traffic demand throughout the day.	No applications found in surveys	Congested travel	VMT; speed counts	Short-term: generally, no threshold changes in short period; adverse effect on congested time of travel might be an exception. Long-term: percentage change in VMT and volume analyzed to reassess the lanes and hours of operation.
Dynamic Lane Reversal (DLR)	Allow existing capacity to better match traffic demand throughout the day.	No applications found in surveys	VMT	Vehicle counts; length of road	Short-term: generally, no threshold changes in short period; adverse effect on congested time of travel might be an exception. Long-term: percentage change in VMT and volume analyzed to reassess the lanes and hours of operation.
Dynamic Lane Reversal (DLR)	Allow existing capacity to better match traffic demand throughout the day.	No applications found in surveys	Throughput—vehicle	Vehicle counts	Short-term: generally, no threshold changes in short period; adverse effect on congested time of travel might be an exception. Long-term: percentage change in VMT and volume analyzed to reassess the lanes and hours of operation.
Dynamic Lane Use Control (DLUC)	Reduce crashes and improve safety.	WSDOT, VDOT	Overall crash rate	Total crashes; VMT	Short-term: manual operation of signs based on incident reports and congested travel/delay. Long-term: crash reports, secondary incidents, and incident reaction time analyzed to adjust the design and execution.
Dynamic Lane Use Control (DLUC)	Reduce crashes and improve safety.	WSDOT, VDOT	Secondary crashes	Crash reports	Short-term: manual operation of signs based on incident reports and congested travel/delay. Long-term: crash reports, secondary incidents, and incident reaction time analyzed to adjust the design and execution.
Dynamic Lane Use Control (DLUC)	Reduce crashes and improve safety.	WSDOT, VDOT	Lane-hours lost due to incidents	Time blocked; number of lane blocked (incident reports)	Short-term: manual operation of signs based on incident reports and congested travel/delay. Long-term: crash reports, secondary incidents, and incident reaction time analyzed to adjust the design and execution.
Dynamic Lane Use Control (DLUC)	Reduce crashes and improve safety.	WSDOT, VDOT	Incident clearance time	Incident reports (logged timesheet during incidents)	Short-term: manual operation of signs based on incident reports and congested travel/delay. Long-term: crash reports, secondary incidents, and incident reaction time analyzed to adjust the design and execution.
Dynamic Shoulder Lane (DShL)	Reduce vehicle density per lane and increase service volume capacity.	MnDOT, SANDAG/Caltrans District 11, Illinois Department of Transportation (IDOT), Florida Department of Transportation (FDOT),	VMT	Vehicle counts; length of road	Short-term: weekly evaluation of vehicle throughput to adjust the time of activation and speed thresholds. Long-term: quarterly and annual evaluation of vehicle hours/miles traveled under and over predefined speeds to reassess the algorithm and manage the shoulder lane effectively.
Dynamic Shoulder Lane (DShL)	Reduce vehicle density per lane and increase service volume capacity.	MnDOT, SANDAG/Caltrans District 11, Illinois Department of Transportation (IDOT), Florida Department of Transportation (FDOT),	Throughput—vehicle	Vehicle counts	Short-term: weekly evaluation of vehicle throughput to adjust the time of activation and speed thresholds. Long-term: quarterly and annual evaluation of vehicle hours/miles traveled under and over predefined speeds to reassess the algorithm and manage the shoulder lane effectively.
Dynamic Shoulder Lane (DShL)	Increase speed, maximize throughput, decrease congestion, reduce secondary incidents, and reduce speed variation near an incident or weather event.	WSDOT, ODOT, MnDOT, WYDOT, UDOT, MoDOT, VicRoads, UK, Netherlands	Operating speed reliability	Speed data with respect to time	Short-term: analysis of speed and throughput trends on a weekly and monthly basis to improve the threshold algorithm. Long-term: evaluation of incident reports and congested travel as key inputs to improve the adaptability to speed changes.
Dynamic Speed Limit (DSpL)	Increase speed, maximize throughput, decrease congestion, reduce secondary incidents, and reduce speed variation near an incident or weather event.	WSDOT, ODOT, MnDOT, WYDOT, UDOT, MoDOT, VicRoads, UK, Netherlands	Throughput—vehicle	Vehicle counts	Short-term: analysis of speed and throughput trends on a weekly and monthly basis to improve the threshold algorithm. Long-term: evaluation of incident reports and congested travel as key inputs to improve the adaptability to speed changes.
Dynamic Speed Limit (DSpL)	Increase speed, maximize throughput, decrease congestion, reduce secondary incidents, and reduce speed variation near an incident or weather event.	WSDOT, ODOT, MnDOT, WYDOT, UDOT, MoDOT, VicRoads, UK, Netherlands	Secondary crashes	Crash reports	Short-term: analysis of speed and throughput trends on a weekly and monthly basis to improve the threshold algorithm. Long-term: evaluation of incident reports and congested travel as key inputs to improve the adaptability to speed changes.
Dynamic Speed Limit (DSpL)	Increase speed, maximize throughput, decrease congestion, reduce secondary incidents, and reduce speed variation near an incident or weather event.	WSDOT, ODOT, MnDOT, WYDOT, UDOT, MoDOT, VicRoads, UK, Netherlands	Congested travel	VMT; speed counts	Short-term: analysis of speed and throughput trends on a weekly and monthly basis to improve the threshold algorithm. Long-term: evaluation of incident reports and congested travel as key inputs to improve the adaptability to speed changes.
Dynamic Speed Limit (DSpL)	Increase speed, maximize throughput, decrease congestion, reduce secondary incidents, and reduce speed variation near an incident or weather event.	WSDOT, ODOT, MnDOT, WYDOT, UDOT, MoDOT, VicRoads, UK, Netherlands	Percentage of hours influenced by weather	Weather reports; measurable precipitation	Short-term: analysis of speed and throughput trends on a weekly and monthly basis to improve the threshold algorithm. Long-term: evaluation of incident reports and congested travel as key inputs to improve the adaptability to speed changes.
Dynamic Speed Limit (DSpL)	Increase speed, maximize throughput, decrease congestion, reduce secondary incidents, and reduce speed variation near an incident or weather event.	WSDOT, ODOT, MnDOT, WYDOT, UDOT, MoDOT, VicRoads, UK, Netherlands	Lane-hours lost due to incidents	Number of lanes blocked; lane density; incident time logged	Short-term: analysis of speed and throughput trends on a weekly and monthly basis to improve the threshold algorithm. Long-term: evaluation of incident reports and congested travel as key inputs to improve the adaptability to speed changes.
Queue Warning (QW)	Reduce rear-end crashes and improve safety.	WSDOT, ODOT, IDOT	Overall crash rate	Total crashes; VMT	Short-term: no adjustments performed. Long-term: evaluation of crash reports to lead to adjustments in speed and occupancy thresholds.
Queue Warning (QW)	Reduce rear-end crashes and improve safety.	WSDOT, ODOT, IDOT	Secondary crashes	Crash reports	Short-term: no adjustments performed. Long-term: evaluation of crash reports to lead to adjustments in speed and occupancy thresholds.

5.2 PERFORMANCE EVALUATION

Performance evaluation is a process undertaken by an agency either post-hoc or on a project or regional level. In this process, an agency collects data and analyzes those data to quantify or justify the deployment of an entire system. For example, after deploying an ATM system, an agency may collect performance data over an extended period of time to quantify the overall benefits of deploying the system to determine if it meets the intended goals and objectives. Performance evaluation is generally an aggregation of cumulative effects of multiple management events over an extended period. Many of the outputs and outcomes of the monitoring process can be used as input in the overall evaluation process.

As it reviews daily events, an agency can learn trends in ATM performance over time and fine-tune the deployment of these dynamic management strategies. Agencies should review what happened during the day as well as attempt to relate changes and modifications made by the deployed ATM strategies to observed performance. Agencies can then adjust deployment thresholds and fine-tune management strategies. Critical data that need to be collected by performance monitoring systems include timestamps associated with each change and/or activation/deactivation of a management strategy; measured traffic and travel conditions at the time the management strategy was changed; and any external events and circumstances that led to a change in a management strategy, such as an incident on an adjacent or complementary facility.

Having access to quality data is an important element of ATM performance evaluation. In most major metropolitan areas, multiple sources of data are available for evaluating the performance of the freeway systems, and agencies are beginning to use data from multiple sources to evaluate the performance of their freeway and arterial street systems and to make operational control decisions. Dashboards are a common tool used by some agencies to present travelers with information on the current conditions of travel in a region. These dashboards frequently compare the current conditions to expected or historical conditions for the same time of day. Figure 30 and Figure 31 provide examples of performance monitoring used by agencies in the United States.

The performance evaluation of ATM includes the aggregation of cumulative effects of management over an extended period of time. This evaluation can support the fine-tuning of the strategies and related algorithms as well as be used to incorporate into planning and justification for future ATM deployments.

Figure 30. Illustration. Example of WSDOT travel time display for Seattle, Washington.⁽⁸²⁾

Figure 31. Illustration. Example of speed performance monitoring at Houston TranStar.⁽⁸³⁾

Most traffic management centers currently perform some type of data logging. System operations logs provide historical logging procedures (manual and automated) as determined by management within the capability of the specific system. Two logs that are important to keep with any ATM deployment are the following:

• Device Activation Log—this log provides a record of when devices were activated and deactivated and what message(s) were posted on each device throughout the duration of ATM activation.
• Device Malfunction/Monitoring Report—this log documents the operational status (e.g., online, offline, out of service, etc.) of every traffic management device in the system and documents the reason the device is not in service (communications failure, device failure, etc.).

With some ATM deployments, such as DSpL, an agency needs to capture and retain the status and content of information displayed on each device. Retention of this information is needed to support enforcement activities in the corridor. With many systems, automatic logging features are most often incorporated into system software applications.

5.3 MAINTENANCE

Most ATM deployments are part of an agency's overall transportation management system (TMS), which is a complex, integrated amalgamation of hardware, technologies, and processes designed specifically to perform an array of functions. Disruptions or failures in the performance of any one of these functions, including ATM, can impact traffic safety and reduce system capacity, and possibly lead to the traveling public losing faith in the transportation network. The complex interdependencies of these systems further complicates maintenance such that a single malfunction can critically impact the ability of the overall systems to perform their intended functions.

System maintenance includes replacing worn components, installing updated hardware and software, tuning the systems, and anticipating and correcting potential problems and deficiencies. Maintenance includes the development and implementation of action plans for responding quickly, efficiently, and orderly to systemic failures, as well as having infrastructure and procedures for measuring and monitoring maintenance activities. The number of components in a system can impact maintenance costs. For example, the way in which DSpL is displayed (i.e., overhead gantry with lane-by-lane signage vs. single shoulder-mounted sign) can make a significant difference in maintenance costs.⁽²⁷⁾ The design of an installation can also impact maintenance. For example, MnDOT sign gantries incorporated a catwalk so that maintenance personnel could access the back of the dynamic message signs (DMSs) on the gantry without closing lanes. The WSDOT installation required a full lane closure for maintenance. Agencies need to consider regional policies regarding maintenance activities and lane closures when designing the system so that regular maintenance costs are reasonable and efficient.

The ITS Joint Program Office maintains a comprehensive costs database for ITS deployments that provides information on system costs—including capital, operating, and maintenance costs—for a variety of applications, many of which are comparable to ATM deployments in terms of the operational elements. The database is available online on the USDOT website (http://www.itscosts.its.dot.gov/).

An agency's maintenance strategy can dictate system design and must be considered in the planning phase to ensure that it will have the personnel or financial resources to adequately maintain the ATM system. Key maintenance decisions that need to be made during the planning portion of a project include the location of maintenance resources, institutional responsibilities, staffing levels and requirements, and use of contract services to maintain agency assets. Table 18 provides an overview of maintenance needs for ATM strategies, while Table 19 includes maintenance considerations that may be unique to ATM strategies and that an agency needs to examine prior to implementation. In all cases, the frequency of maintenance should be per manufacturer recommendations, as technology evolves, as new ITS elements are deployed, and/or as a result of damage or failure.

Table 18. Maintenance needs for ATM strategies.

ATM Strategy	Maintenance Elements	Relative Cost Range
Adaptive Ramp Metering (ARM)	Signal heads; controllers; detectors; signage; ramp metering software; controller upgrades	Low to Moderate
Adaptive Traffic Signal Control ( ATSC)	Signal controllers; control software; hardware platform; detection; controller upgrades; communication	High
Dynamic Junction Control (DJC)	Control software; detection; signage; communication; overhead gantry; lane control signals	Moderate
Dynamic Lane Reversal (DLR)	Control software; detection; signage; communication; overhead gantry; lane control signals; access control system; overhead beacons	Moderate
Dynamic Lane Use Control (DLUC)	Control software; detection; signage; communication; overhead gantry; lane control signals	Moderate
Dynamic Shoulder Lane (DShL)	Control software; detection; signage; communication; overhead gantry; lane control signals; noise barrier; pavement markings	Moderate to High
Queue Warning (QW)	Control software; detection; signage; communication; overhead gantry; overhead beacons; DMSs	Low
Dynamic Speed Limits (DSpL)	Control software; detection; signage; communication; overhead gantry; lane control signals; RWIS	High
Dynamic Merge Control (DMC)	Control software; detection; signage; communication; overhead gantry; lane control signals	Moderate

Table 19. Maintenance considerations (adapted⁷).

ATM Strategy	Maintenance Consideration
Adaptive Ramp Metering (ARM)	Maintenance similar to that for regular traffic signal systems; pole-mounted signal heads may be prone to knockdown by vehicles, requiring additional repair; construction can affect detection systems.
Adaptive Traffic Signal Control ( ATSC)	Construction and other utility work can impact detection; communications and hardware/software maintenance also have to be accounted for.
Dynamic Junction Control (DJC)	No significant maintenance challenges beyond other lane control issues unless in-pavement lighting is used to support merge applications.
Dynamic Lane Reversal (DLR)	Maintenance of pylons and lane separators is always a challenge when they are used to separate reversible lanes; maintenance of core elements; maintenance of any ITS equipment and electronic signage and/or software can be significant.
Dynamic Lane Use Control (DLUC)	The health of signs needs to be consistently monitored because of their importance; replacement signs need to be available and need to be swapped as efficiently as possible.
Dynamic Shoulder Lane (DShL)	Highway appurtenances are closer to traffic and more subject to damage; additional personnel and equipment might be needed to close lanes and provide adequate work-area protection during maintenance; most incidents may require some action by personnel that involves shoulders, which in turn requires shoulders to remain closed until the incident is cleared, items are removed, or other action is completed; emergency vehicles' use of shoulders to access scenes of accidents and delays in arriving on the scene may have consequent increases in periods of congestion, secondary accidents, and clearance time.
Queue Warning (QW)	When implemented with speed harmonization, QW pictograms and/or flashing lights need to be visible to all vehicles; during normal operation, all the signs are blank; the signage should also be consistent and uniform to clearly indicate congestion ahead.
Dynamic Speed Limit (DSpL)	Strategy greatly increases the amount of field equipment to be maintained at a higher level than before; maintenance considerations for overhead signs have to be factored into the design stage.
Dynamic Merge Control (DMC)	No significant maintenance challenges beyond other lane control issues unless in-pavement lighting is used to support merge applications.

5.4 INCIDENT MANAGEMENT

One major challenge associated with ATM is incident management, particularly if an operational strategy has eliminated the ability for vehicles to seek emergency refuge, such as with DShL. Opening the shoulder to traffic during peak periods means the loss of that shoulder as an emergency refuge area in the event of an incident. Those agencies that have deployed DShL have taken a variety of approaches to addressing the incident management issue in a practical manner. The following sections provide a discussion on the more popular incident management approaches.

Incident Management Activities

The most prevalent approach to incident management on facilities with DShL is an increased use of motorist service patrols on the facility. Those agencies that already have a dedicated service patrol to quickly respond to freeway incidents frequently increase coverage in the impacted area when shoulder use is operational to ensure incident response times are minimized. When combined with a typical unified response approach and significant involvement of a traffic management center, patrols can help minimize the negative impact of the shoulder being open to traffic.

Another strategy is to station tow trucks strategically throughout the facility to clear a lane or the shoulder should an incident occur. Furthermore, motorists are encouraged to do everything possible to exit the freeway should they experience vehicle trouble or be involved in a minor crash. Some States even have laws requiring motorists to do so. The installation of accident investigation sites may help encourage this behavior on heavily traveled roadways.

Incident management is particularly important when DShL is in operation. In addition to technologies, agencies can mitigate the loss of the shoulder with such techniques as increased motorist service patrols, staged tow trucks, emergency refuge areas, and closing the shoulder to facilitate access to an incident by emergency response.

Often, agencies will treat an incident on a shoulder that is operational as a typical lane blocking and handle the incident appropriately. Utilizing DMSs, dynamic lane control signs, and other techniques, the agency moves traffic out of the shoulder and responds to the incident accordingly. In this case, an emergency response vehicle may access the facility downstream of the incident and travel upstream on the cleared shoulder to reach the blocked shoulder.

One strategy to supplement the incident management activities is to install automatic vehicle detection, CCTV coverage, and/or emergency call boxes in the emergency refuge area to decrease the notification time for an incident.

Emergency Refuge Areas

As noted previously, the primary concern with opening a shoulder to traffic is the lack of an emergency refuge for disabled vehicles. To overcome this problem, an agency may install a small emergency refuge area beside the shoulder. These areas, often spaced at 0.5-mi intervals, provide motorists a place to pull out of the shoulder traffic in the event of an incident.

5.5 ENFORCEMENT

It is essential that law enforcement officers know and understand the rationale of the ATM strategy. Enforcement approaches for various ATM strategies may vary significantly, given the variety of supporting policies that exist, and can play a critical role in the success of a deployment.

Engaging law enforcement early in the implementation can help an agency gain understanding, feedback, and buy-in from law enforcement regarding both the ATM strategy and that an acceptable enforcement strategy is important. Ongoing discussions with law enforcement are important during the planning and design phases in order to inform personnel about the purpose and expected operations of the ATM strategy. These discussions can help to address the concerns of law enforcement personnel about how the ATM deployment could impact their job duties, and to accommodate their suggestions and needs into the design where possible. If a new ATM strategy is implemented with supporting new policies or laws, a period of issuing only warnings may be beneficial while the public gains an understanding of the new system.

Enforcement considerations are perhaps of greatest concern with the use of variable speed limits as an ATM strategy. Fully automated enforcement of variable speed limits removes the need for law enforcement personnel to patrol the facility, but public support and the policies needed to support automated speed enforcement on freeways are lacking in the United States.⁽⁸⁴⁾ Thus, reliance on law enforcement may be a more realistic option, and an increased law enforcement presence and additional procedures for manual enforcement that are more customized for the new ATM strategy may be needed.⁽⁷⁰⁾

If an agency does not want to create new enforcement policies for variable speed limits or other ATM strategies, it can take a different approach. In Minnesota, for example, ATM signage displays variable advisory speeds that are not enforceable because variable speed limits are not permitted.^(61,79) In Washington, even though the variable speed limits are enforceable (regulatory), the speed limits are effectively advisory because law enforcement does not actively enforce roadways during building congestion to avoid contributing to the congestion.⁽⁶¹⁾ These two cases demonstrate that supporting policy is not always needed to accomplish a similar end, which is to prepare traffic for slower downstream speeds and issue citations for driving at an unsafe speed, regardless of whether the posted speed is regulatory or advisory.

For regulatory ATM strategies, coordination with law enforcement is essential for success. Support from the adjudication process is also beneficial to successful implementation.

Law enforcement may also choose to adapt and apply existing procedures to reduce confusion and level of effort for education and outreach. For instance, instead of establishing a specific variable speed limit policy, law enforcement could issue citations based on basic speed law, which requires drivers to travel at a reasonable and prudent speed for current conditions regardless of the posted or advisory speed. In other cases, it may be preferable for violations and adjudication procedures to be adjusted. A variable speed limit system should archive the displayed speed limit by location and time of day for supporting evidence in court of the speeding violation.⁽⁷⁰⁾

5.6 COSTS

Agencies need to carefully consider costs associated with ATM long before implementation. Costs include the capital investment in not only the infrastructure and technology but also the longer-term operations, maintenance, and upgrade of the system over time. Often, federal funding is available to help pay for ATM strategies and projects, not only for initial construction but also for ongoing costs. Understanding the categories of federal funding in which ATM strategies and projects are undertaken is a first step in matching eligible projects with funding. A variety of federal programs provide opportunities for financing ATM strategies, either alone or in combination with other activities or projects. Other revenue sources at State and local levels may also be available. Program managers should work closely with the agency's programming and financial offices to best understand funding availability and eligibility requirements.

Current federal funding program categories that can provide resources to agencies for ATM are included in Table 20. Included is information on the purpose of the funds and examples of eligible activities related to a wide variety of TSMO functions and activities that would encompass ATM strategies.

Table 20. Description of Federal funding programs that may support TSMO activities.⁽⁸⁵⁾

Federal Funding Program	Purpose	Sample of Eligible Activities Related to TSMO
Congestion Mitigation and Air Quality (CMAQ)	To provide a flexible funding source to State and local governments for transportation projects and programs to help meet the requirements of the Clean Air Act. Funding is available to reduce congestion and improve air quality for areas that do not meet the National Ambient Air Quality Standards for ozone, carbon monoxide, or particulate matter (non-attainment areas), as well as former non attainment areas that are now in compliance (maintenance areas). Construction and operations activities are eligible.	Projects that improve traffic flow, including projects to improve signalization; construct HOV lanes; improve intersections; add turning lanes; improve TSMO strategies that mitigate congestion and improve air quality; and implement ITSs and other CMAQ-eligible projects, including projects to improve incident and emergency response or improve mobility, such as real-time traffic, transit, and multimodal traveler information.
Highway Safety Improvement Program (HSIP)	To achieve a significant reduction in traffic fatalities and serious injuries on all public roads, including non-State-owned public roads and roads on tribal lands. A highway safety improvement project is any strategy, activity, or project on a public road that is consistent with the data-driven Strategic Highway Safety Plan and corrects or improves a hazardous road location or feature or addresses a highway safety problem. Construction and operations activities are eligible.	Installation of a priority control system for emergency vehicles at signalized intersections. Collection, analysis, and improvement of safety data. Planning of integrated, interoperable emergency communications equipment, operational activities, or traffic enforcement activities (including police assistance) relating to work zone safety.
National Highway Performance Program (HSPP)	To support the condition and performance of the National Highway System (NHS), to construct new facilities on the NHS, and to ensure that investments of Federal-aid funds in highway construction are directed to support progress toward the achievement of performance targets established in an asset management plan of a State for the NHS. Construction, maintenance, and operations activities are eligible.	Operational improvements of NHS segments, which include capital improvements for installation of traffic surveillance and control equipment; computerized signal systems; motorist information systems; integrated traffic control systems; incident management programs; and transportation demand management facilities, strategies, and programs. Capital and operating costs for traffic and traveler information, monitoring, management, and control facilities and programs. Infrastructure-based ITS capital improvements.
Statewide Transportation Plan (STP)	To provide flexible funding that may be used by States and localities for projects to preserve and improve the conditions and performance on any Federal-aid highway, bridge, and tunnel project on any public road, pedestrian and bicycle infrastructure, and transit capital projects, including intercity bus terminals. MPOs are given full project selection authority over portions of STP funding (called urban allocation). Construction, maintenance, and operations activities are eligible.	Operational improvements for highways. Capital and operating costs for traffic monitoring, management, and control facilities and programs, including advanced truck stop electrification. Infrastructure-based ITS capital improvements.
Statewide and Metropolitan Planning Funds:State Planning and Research	To establish a cooperative, continuous, and comprehensive framework for making transportation investment decisions in metropolitan areas and on a statewide basis. Planning and research activities only. Establishes funds to be used for a wide variety of State transportation research activities. Only planning and research activities are eligible for funding.	State planning funds are used to support federally required long-range and short-range planning functions as well as research carried out at the State level. Metropolitan planning funds may provide for MPO staff support for regional transportation operations coordination, regional operations guideline development, minor studies, and other staff activities to support regional TSMO programs. Research funds can be used to research ATM strategies, deployments, cost-benefit of ATM, etc.

Federal funding of ATM strategies or projects, as shown in Table 20, can come from a wide range of categories. All of the ATM strategies that are covered in this Guide are eligible for funding since they are directly related to improving travel time reliability, congestion reduction, and safety. To further illustrate the types of projects that could be funded, listed below are some of the types of installations and integrations of intelligent transportation systems (ITS) infrastructure that qualify for Federal funds:

• Regional management and operations program planning.
• Traffic signal control systems.
• Freeway management systems.
• Incident management systems.
• Multimodal traveler information systems.
• Transit management systems.
• Electronic toll collection systems.
• Electronic fare payment systems.
• Railroad grade crossing systems.
• Emergency services.
• National ITS Architecture implementation for metropolitan and rural areas.
• Regional ITS architecture development.

Examples of typical Federal-aid, capital improvement projects that may include eligible operating costs are:

• System integration.
• Telecommunications.
• Reconstruction of buildings or structures that house system components.
• Control/management center (construction) and system hardware and software for the projects.
• Infrastructure-based intelligent transportation system capital improvements to link systems to improve transportation and public safety services.
• Dynamic/variable message signs.
• Traffic signals.

Examples of typical eligible operating cost and expenses for traffic monitoring, management, and control include:

• Labor costs.
• Administrative costs.
• Utility and rent costs.
• Other costs associated with the continuous operation of the above-mentioned facilities and systems.
• System maintenance (activities to assure peak performance).
• Replacement of defective or damaged computer components and other traffic management system hardware (including street-side hardware).⁽⁸⁶⁾

As discussed previously, ATM involves hardware, software, and software integration. As such, agencies need to consider the long-term support of that software, including the need to perform periodic upgrades and modifications to control operational scenarios.

Different areas of staff education and training must also be considered, which impacts costs. ATM strategies generally require more complex ITS that may be unfamiliar to agency planners, designers, construction personnel, and transportation management center (TMC) operators. The following are specific training efforts that an agency can consider:

• Peer-to-peer exchanges with other transportation agencies that operate similar ATM deployments, to include document sharing, teleconferences, webinars, or site visits for key agency personnel.
• Structured mentoring and training between experienced operators and junior operators to formally provide junior operators additional learned knowledge regarding complex operations, automated features, and decision support system responses.
• Cross-training to ensure sufficient operations staff are available to facilitate 24/7 operations and to cover in the event of staff absences or departures.
• Safety training for personnel in the field, including maintenance staff, law enforcement, incident response teams, emergency management, and transit drivers, especially if ATM in any way impacts how they conduct their job duties.

ATM Application: WSDOT determined costs of operations and maintenance associated with ATM deployments along I-5, SR 520, and I-90. The estimated budget for maintenance was approximately $317,000 per year. Maintenance activities involve repairs to malfunctioning signs, maintaining communications networks, and electricity costs. The estimated operations budget was approximately $184,000. Operations activities include monitoring and controlling ATM devices, reviewing and analyzing system operations to identify and implement refinements, developing and testing software modifications, training operators, planning special events, and coordinating operations with local agencies. Active Traffic Management Report, Washington State Department of Transportation, 2013, https://app.leg.wa.gov/ReportsToTheLegislature/Home/GetPDF?fileName=ATM%20Report%20January%202013_4e6795ed-fd51-41f6-9e9a-9a674cfd61c5.pdf. MnDOT's Smart Lanes costs are comparable to those for WSDOT. The cost to install the ATM elements including intelligent lane control signals and gantries, speed harmonization, and incident management, was $22.6 million. Annual operating expenses are $300,000. ITS JPO Costs Database, http://www.itsbenefits.its.dot.gov/ITS/benecost.nsf/ID/E7E3DC47A960631085257CE8005589F2?OpenDocument&Query=CApp.

You may need the Adobe® Reader® to view the PDFs on this page.