Active Traffic Management (ATM) Implementation and Operations Guide

CHAPTER 2. PLANNING AND ORGANIZATIONAL CONSIDERATIONS

Planning for an active traffic management (ATM) implementation is a multifaceted and complex process. Since ATM still represents an emerging strategy in many regards, with it comes new approaches needed to effectively plan for ATM and integrate ATM into current plans and planning processes. This chapter provides an overview of planning-level and organizational approaches that agencies need to consider when developing ATM for a corridor or across a region. This chapter includes the following sections:

• Planning for ATM Operations. This section discusses specific efforts that an agency undertakes to plan for operations, including scenario planning, use of data, and the difference between planning from a corridor perspective versus subareas.
• Organizational Capability for ATM Operations. This section provides an overview of the organizational capability concepts that support successful ATM operations on a regional basis.
• Setting Objectives and Performance Measures for ATM. This section describes the importance of identifying objectives and performance measures for regional operations.
• Analysis, Modeling, and Simulation. This section discusses the types of analyses that an agency can conduct to assess the feasibility and potential impacts of ATM strategies on specific corridors.
• Programming and Budgeting. This section describes strategies for programming and budgeting for ATM strategies on a regional basis.

2.1 PLANNING FOR ATM OPERATIONS

Planning for ATM operations requires leveraging of ongoing efforts and institutional partnerships in a region. These partnerships serve as the foundation for such efforts as freeway management and operations, regional traffic incident management, and arterial traffic management and operations. As transportation systems management and operations (TSMO) has become more mainstreamed into agency operations, agencies have recognized that there is a need for increased focus on the institutional elements of a regional transportation operations strategy. Planning for operations is structured around an objective-driven, performance-based approach, as illustrated in Figure 19. The rationale for this approach is to link planning and operations to improve transportation decisions to effectively enhance the overall network by ensuring investments work to meet regional goals and objectives.⁽³¹⁾

For more information on how agencies have incorporated ATM into planning efforts, visit VCTIR's website (www.virginiadot.org/vtrc/main/online_reports/pdf/13-r1.pdf).

Figure 19. Diagram. Objective-driven, performance-based approach to planning for operations (adapted³¹).

As a result, a TSMO program plan that incorporates ATM strategies will typically go beyond traditional infrastructure and deployment needs and identify how agencies and regions can address ATM project planning, life-cycle costing of equipment and other infrastructure investments, operations and maintenance of the ATM systems which can be more complex that traditional intelligent transportation systems (ITS) investments, institutional collaboration for various scenarios and ATM strategies, and other parameters. Specific aspects of planning for ATM operations can include scenario planning, using data in planning, planning in subareas as opposed to corridors, and engaging stakeholders, all of which are essential for successful ATM implementation.

Scenario Planning

Scenario planning entails the development of ATM strategies within a given context. Scenarios can vary by specific environmental or background characteristics, such as deploying ATM strategies during planned events (work zones or special demand generator) and in response to incident or emergency conditions (closed lanes or inclement weather). Preferably, agencies should describe ATM operational scenarios from a user perspective, inclusive of typical day-to-day operations. A predetermined ATM operational plan can detail how normal, or recurrent, ATM operations would function in addition to specific scenarios that would necessitate change or unique application. For example, if dynamic shoulder use is to be deployed along a facility, the operating agency needs to determine how that shoulder will be managed in the event of an incident. Potential scenarios could include (a) opening the shoulder to traffic if not already operational to help alleviate congestion caused by the incident, or (b) closing the shoulder to traffic if already open to accommodate emergency response personnel to access the incident. In either scenario or some other variation, the operating agency needs to determine how the strategy will be deployed, for what purpose, for what duration, and identify other stakeholders and partners need to be incorporated into the decision to implement the scenario. Planning elements that may be included within an ATM scenario plan are agency roles and responsibilities, traveler information needs specific to the dynamic nature of the ATM strategies, system interoperability (how different components of the ATM systems interact and communicate with other ITS infrastructure in place and any legacy systems), stakeholder roles, and risk allocation. Simulation exercises can help agencies assess various ATM scenarios and operational strategies by evaluating the impact of specific components or the inclusion of select user groups.

Use of Data in Planning

The use of data for planning ATM strategies principally involves collecting accurate and reliable data. Overall, data needs are linked to monitoring and modeling needs. Data enhance an agency's ability to determine the extent and duration of congestion and system performance and to estimate potential performance benefits on the network of an ATM strategy.⁽³²⁾ For operational purposes, data often require detailed granularity that can allow analysts to examine the potential for incremental changes at specific locations. Longitudinal data are necessary for seasonal and year-to-year comparisons. Data needs are typically driven by the establishment of performance metrics, as defined by the regional needs and goals of the project or program.

Sources for data can vary. Data for ATM may originate from regular data collection programs or special studies, usually in conjunction with implementing a new ATM strategy. A range of entities can provide data on a continual or regular basis, and may include internal agency groups or private third parties. Examples include travel demand models, transportation management center data, transit ridership records, crash records, third-party mobility data, or citation data.⁽³²⁾ More agencies are relying on private entities to provide data, particularly for measuring mobility and congestion. Agency coordination is important in the planning phase to facilitate data sharing, help determine ATM strategies to implement, and prioritize corridors and areas for those strategies. As ATM strategies are incorporated into the planning process, agencies need to ensure that data is identified and collected to support the performance measures used in that process.

Subareas vs. Corridors

Planning for operations of ATM strategies should be undertaken within the overall context of a region. As part of an overall TSMO approach, agencies should include ATM and how it can play a role in operational planning within a subarea or within a corridor. A subarea is a defined portion of a region, and planning within that segment of the region is accomplished in greater detail with respect to analyses and recommendations for TSMO opportunities.⁽³³⁾ This subarea can include a municipality, an activity center, a downtown, or some other logical segment of a region. A corridor is typically comprised of a collection of parallel routes either within or through a region and incorporates all of the transportation services provided within that travel shed.⁽³⁴⁾ As an agency considers ATM in the region, it must understand how ATM strategies may enhance mobility and operations within either of these regional elements. While planning for ATM may be similar for both elements, an agency should consider any specific nuances of these strategies in meeting mobility and livability goals, particularly any strategies that might support mode shift and mobility choices for system users.

Visit FHWA's website for more information on planning for TSMO within subareas (https://ops.fhwa.dot.gov/publications/fhwahop16074/index.htm) and along corridors (https://ops.fhwa.dot.gov/publications/fhwahop16037/index.htm).

Stakeholder Engagement

Most major transportation improvement projects use effective stakeholder engagement and support to ensure successful implementation. Due to the nontraditional nature of ATM, outreach is necessary to inform critical audiences about basic concepts, purposes, and expected outcomes for each strategy. Audiences typically include impacted stakeholders, project champions, elected and appointed officials, media, and the public. Project champions can generate support both within and outside the implementing agency. Champions can initiate dialogue and help to ease the planning process that can involve multiple stakeholders. Champions do not need to consist of elected officials, and can consist of prominent individuals from the business community or volunteer organizations. Stakeholders can include representatives from county and city agencies, enforcement personnel, transit agencies, and emergency services. Effective strategies for stakeholder engagement may include forming an internal working group to discuss critical issues, developing outreach materials (e.g., short one- to two-page handouts), hosting information booths at public events, and implementing targeted social media campaigns.

ATM Application: The conventional transportation planning process can be adapted to accommodate planning for ATM strategies by modifying the process to address unique aspects of ATM. Specific adaptations that support ATM projects focus on operations projects, which are inherently different from traditional capital improvement projects. Specific enhancements to the conventional transportation planning process that can support ATM projects include: Incorporating processes in addition to projects in the planning process by describing ATM deployments as operations initiatives. Emphasizing performance measures for ATM strategies over technologies to incorporating reliability-based metrics to present operational investments on an equal level with capacity investments. Explicitly including ATM operational strategies into the traditional planning process, including within the context of other regional goals, to help secure allocated funding. Estimating benefits of ATM operational strategies at a sketch planning level to include in the long-range planning process. Planning for Active Traffic Management in Virginia: International Best Practices and Implementation Strategies, 2012, VCTIR 13-R1, http://www.virginiadot.org/vtrc/main/online_reports/pdf/13-r1.pdf.

Washington State Department of Transportation (WSDOT) initiated stakeholder engagement during the feasibility study for the I-5 ATM deployment. The agency incorporated such efforts as workshops and regional forums in the initial stages and involved representatives from Federal Highway Administration (FHWA), Washington State Patrol, Puget Sound Regional Council (PSRC), elected officials, decision makers, and local agencies. Virginia Department of Transportation (VDOT) required communications and outreach for the I-66 project development and deployment, including the development of a comprehensive communications plan that incorporates procedures for public outreach with stakeholders, elected officials and agencies; media relations that included paid advertising, media events, and media protocols to share information and promote consistent messages; a comprehensive communication program to educate motorists and stakeholder groups; and project branding.⁽³⁵⁾

2.2 ORGANIZATIONAL CAPABILITY FOR ATM OPERATIONS

ATM is a significantly more integrated approach toward real-time operations and rests on a foundation of robust systems management. Funding, right-of-way constraints, and environmental impacts limit the ability of agencies to implement traditional capacity improvements such as widening to add new lanes to meet increasing traffic demand. Thus, a significant shift from the historic build and maintain mission of many organizations to a more formal, programmatic approach to operating facilities for improved travel time reliability and congestion reduction is needed. ATM strategies offer innovative solutions to increase capacity during peak times of demand as a lower-cost, quicker solution that can be implemented within the existing right-of-way. Because of this characteristic, aggressively and proactively managing transportation systems, and ATM specifically, is a new mission for many agencies. Agencies with a very low level of capability in systems management and operations are probably not ready for ATM deployment, lacking the adequate business processes, supporting technology, and required workforce to be effective.

Organizational Capability Maturity Model (CMM) tools can assist transportation agency managers with self-assessments of their organization's development in six dimensions: (a) business process, (b) systems and technology, (c) performance measurement, (d) culture, (e) organization and workforce, and (f) collaboration. Such tools can help guide the development of institutional architectures and a more formal systems operations and management program that includes the adoption of ATM strategies (see references 36, 37, 38, and 39).

Broadly, these tools can be used by agencies to address the non-technological challenges involved in creating a TSMO program. Moving TSMO activities and projects into mainstream agency practice is a key pathway to agency success in adopting and implementing ATM as a formal consensus-driven approach to identify the institutional barriers that prevent the successful implementation of operational strategies or programs. The levels of organizational maturity defined by the FHWA CMM, as shown in Figure 20, move from level 1 with some programs mostly information and champion driven, to level 2 with some developed processes, to level 3 where performance is measured and programs are formally budgeted, to level 4 where formal partnerships exist and performance-based improvements are the norm.

Figure 20. Graphic. The four levels of organization maturity (adapted⁽⁴⁰⁾).

The FHWA Traffic Management Capability Maturity Framework (TM CMF) is structured around these four levels of organizational maturity for the aforementioned six dimensions of capability. The TM CMF includes a self-evaluation tool for an agency to understand its current levels of capabilities.⁽⁴¹⁾ Based on the level at which an agency resides for each dimension, a list of actions that the agency can undertake to advance its capabilities to the next level is provided. High-level capabilities in the six dimensions are certainly not a prerequisite for an agency to successfully deploy and operate ATM strategies, though at a minimum, an agency should at least be on its way to level 2. However, as an agency matures in these six dimensions to level 3 and level 4, it will be better equipped and more effective at proactively managing ATM deployments.

The six dimensions of organizational capability described below can be used to help agencies identify the current state of their operations programs and to provide guidance for improved levels of program effectiveness. These dimensions represent the key areas where an organization's capability will have a measurable impact on its ability to be operations focused.

The Traffic Management Capability Maturity Framework can help guide the development of ATM strategies and ensure agencies are capability of successfully implementing and operating ATM to meet regional goals.

Business Processes

Scoping, planning, evaluation, and budgeting processes are key business process elements to examine. Evidenced from various statewide operations plans and ITS strategic plans, the role of operations strategies is becoming increasingly clear. With the emphasis on planning for operations, leading departments of transportation (DOTs) are developing robust practices to include operations strategies such as ATM in the planning, programming, and prioritization processes. Given the broad range of operational strategies and the experimental nature of ATM strategies, agencies may need to address and modify business process elements for greater consideration and adoption of ATM strategies. Agencies may try to leverage funding for ATM from nontraditional sources. Many agencies have implemented ATM projects as part of a larger, more comprehensive project that may already be in the planning stages.

Systems and Technology

The systems and technology dimension considers how agencies are responding to the upgrading, replacement, and integration of systems in the world of rapidly changing technologies. Nationally, operations agency personnel and management have an excellent understanding of the systems approach, architecture use, and standardization, especially for ITS projects that are federally funded and thereby require the use of systems engineering. While some operational strategies have become fairly standard and commonplace, the ongoing maintenance, management, replacement, and upgrading of systems is a challenge to most organizations, and these challenges will most likely also apply to ATM systems, which involve new technology that is unfamiliar to many agencies. Additionally, the dynamic nature of ATM systems requires significant sensor and communications investment that increases the complexity of the ITS infrastructure needed to operate the systems. Thus, agencies will need to ensure that the capabilities are in place to support these complex systems and ensure reliable operations to optimize performance.

Performance Measurement

Performance measurement plays a significant role in garnering public support for an agency's projects. It is also used to gauge how well an agency performs and the public perception of that agency's performance. With respect to ATM, agencies should be ready to define the problem metrics, establish measurable goals, and measure system performance when considering ATM strategies for the region. Measuring performance of ATM strategies needs to be better understood, thereby emphasizing its importance as a capability dimension. As noted previously, reliability performance metrics along with specific data needs to determine those metrics can be effective measurements for ATM strategies. Additionally, the metrics identified for use need to clearly relate to those regional goals and objectives that the ATM strategies are intended to help meet. Related to performance measurement is the ability to collect the ATM system data upon which those metrics are based.

For more information on assessing agency capability, visit FHWA's Business Process Frameworks website (https://ops.fhwa.dot.gov/tsmoframeworktool/).

Culture

Agency culture is important in promoting ATM throughout an organization. A new role as an active operator of a system or network to improve throughput, reduce congestion, and increase travel time reliability requires leadership vision, communications, and changes in the organizational decision making. ATM deployments need to be supported by the respective agency decision makers, and constant engagement and communication are essential to promote ATM as a core operating philosophy. Increased education and outreach to policy makers and decision makers within the agency can help to facilitate this cultural transition.

Organization and Workforce

State and other operating agencies are always challenged with retaining quality operations employees, attracting additional quality staff, and determining the need for training on subjects such as lessons learned from other agencies in the deployment of operational strategies, costs/benefits of operational strategies, and technology. The challenges of maintaining a skilled workforce equally apply to ATM operations, which will likely require a greater number of skilled staff, specifically at the transportation management center (TMC). Dynamic operations, which are likely to be 24 hours a day, 7 days a week, can require additional staffing and skills an agency may not have. Furthermore, the technologies supporting these strategies may be more complex than traditional ITS deployments. Comprehensive training is needed for agency staff to become familiar with the functionalities of new systems prior to deploying new ATM strategies.

Collaboration

The collaboration dimension continues to increase in importance with respect to operations since congestion issues on highway networks are not bound by the organizational or geographic boundaries. As congestion spreads to encompass broader areas, more formal partnerships and collaborations will be required. Agencies recognize the importance of collaboration, especially at an operational and implementation level, yet formal relationships are infrequent and hard to document. Many ATM strategies may benefit from or require data, cooperation, and agreements that span multiple agencies, making collaboration necessary. Involvement of other stakeholders, such as law enforcement agencies, is also necessary for successful ATM strategies.

From an ATM perspective, these six dimensions serve as a good organizing framework for the agency. Assessment of the capability levels for an individual agency is relatively straightforward and useful input for determining areas of improvement that will help to assure successful ATM operations.

2.3 SETTING OBJECTIVES AND PERFORMANCE MEASURES FOR ATM

ATM strategies usually require more regular monitoring and maintenance of performance, given the significance of overall program goals and scrutiny of newly implemented strategies. Agencies and stakeholders should try to match suitable performance measures to individual goals and objectives. The selection of performance measures should also be driven by the capability to collect data and the level of analysis necessary for calculation. Table 11 provides a summary of common objectives and performance measures for selected ATM strategies. It is important that these objectives be SMART: specific, measurable, attainable, realistic, and time-bound.⁽³²⁾

Key performance measures for analyzing ATM strategies include travel time reliability, delay, reliable throughput, fuel consumption, emissions, and crashes.

Table 11. ATM objectives and performance measures.

ATM Strategy	Objectives	Performance Measures
ARM (Adaptive Ramp Metering)	Delayed onset of mainline lane breakdown by X minutes by year Y; reduce mainline lane travel delay by X minutes by year Y; reduce ramp delay as freeway demands subside by X minutes by year Y; reduce vehicle hours traveled by X percent by year Y; reduce crash rates by severity and facility type by X percent by year Y.	Mainline lane travel time; duration of mainline breakdown; time of mainline lane breakdown; mainline lane delay; ramp delay; crash rate; crash severity.
ATSC (Adaptive Traffic Signal Control)	Reduce arterial travel time by X minutes by year Y; reduce arterial travel delay by X percent by year Y; improve arterial travel time reliability by X percent by year Y; reduce number of stops by X percent by year Y; reduce intersection delay by X minutes by year Y; reduce queue lengths by X percent by year Y; increase arterial speeds by X mph by year Y.	Arterial travel time; arterial travel time index; arterial travel time reliability; intersection delay; number of vehicle stops at intersection; queue length; arterial speed.
DJC (Dynamic Junction Control)	Reduce travel time by X minutes by year Y; reduce travel delay by X percent by year Y; reduce ramp delay by X minutes by year Y; increase travel speeds by X mph by year Y.	Mainline lane travel time; duration of mainline lane breakdown; time of mainline lane breakdown; mainline lane delay; ramp delay; crash rate; crash severity; mainline lane speed.
DLR (Dynamic Lane Reversal)	Increase throughput during lane reversal operations by X percent by year Y; decrease travel times by Z minutes by year Y; decrease crash rates by severity and facility type by X percent by year Y.	Mainline travel time; mainline lane delay; mainline lane speeds; throughput; crash rate; crash severity.
DLUC (Dynamic Lane Use Control)	Increase capacity when used with dynamic shoulder use by X percent by year Y; increase lane-level volumes by X percent by year Y; reduce secondary accidents by X percent by year Y; increase compliance with posted signage during different flow conditions by X percent by year Y; improve responder safety by reducing crashes involving responders by X percent by year Y.	Travel time; delay; throughput; crash rate; crash severity; crashes involving responders.
DShL (Dynamic Shoulder Lane)	Reduce travel time by X minutes by year Y; increase travel time reliability by X percent by year Y; reduce crash rates by severity by X percent by year Y.	Mainline lane travel time; mainline lane delay; mainline lane travel time reliability; mainline lane speed; crash rate; crash severity; throughput.
QW (Queue Warning)	Reduce rear-end crashes where the warning is in effect by X percent by year Y; increase travel speeds by X mph by year Y; reduce speed differential by X mph by year Y.	Crash rate; crash severity; mainline lane speed; speed differential.
DSpL (Dynamic Speed Limit)	Reduce difference between posted speed versus actual speed by X percent by year Y; reduce speed variability by X percent by year Y; reduce spatial extent of congestion by X distance by year Y; reduce temporal extent of congestion by X minutes by year Y; reduce crash rates by severity by X percent by year Y.	Speed differential; speed variability; mainline lane travel time; mainline lane travel speed; time of mainline lane breakdown; duration of mainline lane breakdown; physical length of mainline lane breakdown; crash rate; crash severity.
DMC (Dynamic Merge Control)	Reduced rear-end crashes where the merge is in effect by X percent by year Y; increase travel speeds by X mph by year Y; reduce speed differential by X percent by year Y; reduce travel time delay by X minutes by year Y.	Travel time; delay; crash rate; crash severity; speed; speed differential.

Travel Time Reliability

Travel time reliability is a key aspect of performance that symbolizes the larger effect of day-to-day variation in travel conditions. Traditional measures related to travel speed and delay do not capture the dimension of reliability, so other metrics are typically used. Specific characteristics help guide the selection of travel time reliability performance measures, as defined by specific goals, availability and quality of data, and geographic scope and intent of the program. Common reliability metrics include the planning time index, buffer index, and number of days below specified threshold.

The buffer index (BI) is a measure of travel reliability that can account for the varied distribution of travel times due to non-recurrent congestion. Traffic incidents, crashes, and the weather all count as causes of non-recurrent congestion. The BI is equivalent to the extra time travelers must add to their average travel time when planning trips. Specifically, the BI is defined as the ratio of the difference between the 95th percentile and average travel times to the average travel time.

The planning time index (PTI) represents how much total time a traveler should allow for ensuring on-time arrival, as opposed to additional time represented from the BI. PTI is useful because it can be compared to the travel time index. The difference between the PTI and the travel time index is the use of the 80th percentile (or 95th percentile, depending on the situation) travel as opposed to the average travel time. The PTI is usually greater than the BI because the PTI is influenced more by non-recurrent congestion. Data can be aggregated by peak hour, peak time period, and daily time periods.

The concept of assessing the number of days per month operating below a set speed threshold is meant to capture a measure of travel reliability that is more readily understood by the traveling public. It can be easier to grasp the notion of days of unsatisfactory performance, as opposed to a dimensionless buffer or planning time index. This measure can be best captured through aggregating data by tolling zone to evaluate where degradation exists in the corridor.

Congestion Management

Beyond travel reliability, multiple dimensions of mobility should be assessed within an ATM performance measurement program. Commonly, an appropriate characterization of performance should include the extent of congestion, or the size of the population and user groups impacted by degraded conditions. Vehicular and person-based throughput are typical measures used to describe the extent of congestion. The number of bottlenecks within a corridor or defined subarea is another commonly used metric.

Vehicle throughput is a measure of performance that assesses, as a whole, the number of vehicles served by a facility or a system. The measure is usually calculated by using data collected by traffic counting equipment that may be installed temporarily (e.g., automated traffic recorders) or as part of existing ITS components. All State DOTs are required to collect and maintain databases with historical vehicle count data for highways that are part of the National Highway System, which includes most major roads and streets.

Person throughput is a measure of performance that assesses, as a whole, the number of people served by a facility or a system regardless of particular travel mode used. The measure is commonly calculated by conducting vehicle occupancy counts to gather a sample of the number of passengers per vehicle per mode (since knowing the number of all the passengers within a vehicle is limited by currently applied technology) and multiplying that figure by the number of vehicles by detected mode. People riding transit are usually counted by factoring the number of detected transit vehicles by the average ridership per route, typically given in an operations report.

The number of bottlenecks is an easy-to-describe metric for describing mobility challenges, especially for nontechnical audiences. This metric identifies the number of known problem locations that could be listed within an improvement plan. Bottlenecks can be grouped by either specific corridors or a geographic subarea.

Safety

Safety is an important goal that often justifies the purpose and funding of implementing an ATM strategy. Compared to mobility and congestion, assessing safety-related performance usually requires years to collect enough baseline data to justify a statistical sound evaluation process that supports valid conclusions. The selection of specific metrics is related to the overall safety goals for the program, the availability and quality of data, and the type of geography for the assessed ATM strategy.

Sustainability and Livability

Performance related to sustainability and livability is usually tied to metrics that assess environmental characteristics. Oftentimes within an ATM context, environmental measures include elements that entail emission of volatile compounds and local impacts on noise. An assessment of air quality entails quantifying the change in ozone precursors over time, specifically nitrogen oxides (NOx) and carbon monoxide (CO). Energy and fuel use, as measured by gallons of gasoline, is another metric that can be associated with assessing environmental impact.

ATM Application: Agencies in the U.S. that have deployed ATM strategies have selected various objectives and performance measures for their specific ATM deployments at both the planning and operational stages. Examples include: Throughput (adaptive ramp metering) [DVRPC]. Crashes, lane speed variance, average speed, (dynamic speed limits, queue warning) [Mn/DOT]. Primary crashes, secondary crashes, severity of crashes, incident duration, congestion, reliability, throughput, emissions, fuel consumption (speed harmonization, queue warning, hard shoulder running) [VDOT]. Crashes, crashes during construction, crash severity (dynamic speed limits, dynamic lane use control, queue warning) [WSDOT]. Travel time, crashes, crash severity, queue lengths, speed differential (dynamic speed limits) [GDOT]. Speed, speed variation, speed limit compliance (dynamic speed limits) [WYDOT].

2.4 ANALYSIS, MODELING, AND SIMULATION

Simulation and modeling exercises help project sponsors and agencies evaluate various ATM strategies at either the planning, design, or operational stages. The process to undergo an analysis or develop a simulation entails the integration of specific components, usually consisting of a set of scenarios, data, model environment, and decision support system. Sets of scenarios provide planners with a number of options regarding lane closures, differing traffic patterns, and varied levels of demand. Collected data support elemental input for analysis. Model environments characterize the format and arrangement for the processes of computations and assumptions. Decision support systems provide the basic framework for evaluating different choices, based on estimated measures of effectiveness.

FHWA has developed a guide agencies can use for the highway capacity and operations analysis of ATDM strategies. It is available on the FHWA website (https://ops.fhwa.dot.gov/publications/fhwahop13042/index.htm).

Planners often use a variety of tools and models to simulate various ATM strategies. Based on practice, no mandate or preference exists to use a specific tool or software package. However, the analysis of specific ATM strategies may benefit from one type of model or simulation over another. Approaches to modeling include microscopic, mesoscopic, and macroscopic (e.g., travel demand analysis), usually defined by the scale of analysis and whether the exercise is more focused on understanding microscopic traffic impacts (e.g., vehicle headway) or macroscopic travel behavior (e.g., trip generation and distribution). Table 12 provides an example summary of a few application scenarios, and analysis types for select ATM strategies for use by agencies.

Table 12. Modeling and simulating ATM.

ATM Strategy	Application Scenarios	Analysis Tool Type
ARM (Adaptive Ramp Metering)	Use signal optimization to determine entry flow rates, storage space, acceleration distance, and entry flow rates using algorithm (i.e., Asservissement liné aire d'entré e autoroutie [ALINEA]).	Travel demand model, microscopic simulation
ATSC (Adaptive Traffic Signal Control)	Help design roadway capacity, turning bays, storage lengths	Travel demand model, microscopic simulation
DJC (Dynamic Junction Control)	Use junction control to dynamically allocate lane access; increase capacity/time-dependent closures.	Microscopic simulation
DLR (Dynamic Lane Reversal)	Determine emergency management, incident management, special events, and long-term congestion implications	Microscopic and mesoscopic simulation
DLUC (Dynamic Lane Use Control)	Determine optimal locations of where to place dynamic lane control signs mounted over traffic.	Microscopic and mesoscopic simulation
DShL (Dynamic Shoulder Lane)	Focus on incident management planning, managed lanes.	Microscopic and mesoscopic simulation
QW (Queue Warning)	Determine optimal locations of DMSs.	Microscopic simulation
DSpL (Dynamic Speed Limit)	Determine policy-related questions regarding speed reduction limits, time-of-day implementation.	Microscopic simulation

FHWA has sponsored a variety of research efforts related to the development of analysis, modeling, and simulation (AMS) active transportation and demand management (ATDM) and dynamic mobility application test bed planning, development, and evaluation. These efforts include the development of an initial screening report, a test bed preliminary evaluation plan, and a series of foundational research efforts assessing an AMS concept of operations (ConOps), capabilities assessment, and analysis plan.

Mobility Analysis

Mobility is often a strong goal and objective that drives the planning for implementing ATM strategies. Oftentimes, the tools used for assessing impacts rely on simulations and modeling at either the microscopic or mesoscopic level. These modeling approaches entail an assessment of traffic flow and driver behavior within specific segments of a highway network, particularly dynamic lane changes and dynamic shoulder use strategies. Larger-scale macroscopic models consider impacts to the greater transportation network using data and assumptions about speed, flow, and density. Macroscopic models can be very useful for evaluating ATM strategies based on changing driver route choice, as opposed to lane choice. QW is an example of an ATM strategy that would benefit from macroscopic modeling. Other tools and modeling packages that could be utilized for mobility analysis might include State and regional travel demand models, tools based on the Highway Capacity Manual, and traffic signal optimization tools.

For more information on ATDM research results related to modeling, visit FHWA's ATM website at (https://ops.fhwa.dot.gov/atdm/research/index.htm#completed).

Safety Analysis

Safety is another common goal and objective for implementing ATM. However, the analytical and modeling packages for ATM are limited compared to similar tools for mobility analysis. A major consideration is the reliance on historical and longitudinal data for an effective safety analysis. Usually, a minimum of 3 years of crash and incident data are required to undergo a statistically valid assessment. The long time period is required to consider the impacts of possible outliers, including specific weather incidents or special generators of traffic demand. Safety-related data are limited to the instruments used for reporting incidents and crashes. Crash reports do not often include space to report incident locations for specific lanes, which would be required for dynamic lane or shoulder use strategies. Reports may also include erroneous geocoded location data that do not match exactly where the incident occurred. Similar traits exist when using incident data from TMCs. Given the characteristics and limitations on the use of safety data for analysis, project sponsors should manage expectations about safety analyses.

Environmental Analysis

The Clean Air Act requires the Environmental Protection Agency (EPA) to set limits on the amount of certain pollutants allowed in the air. Urban areas that exceed EPA standards are said to be in non-attainment. States are required to develop an implementation plan to bring the area back into compliance, or its cities face losing vital Federal funding. Common pollutants of concern include NOx, CO, and volatile organic compounds. In addition, particulate matter is a concern for some areas around the country. ATM might be seen as a mechanism for addressing air pollution as part of a larger TSMO program that emphasizes system efficiency and overall mobility improvements. Agencies can estimate emissions for ATM strategies for vehicles with a variety of modeling tools, one in particular being EPA's emissions rate program called Mobile Source Emissions Model (MOBILE). Three key activity measures for estimates include vehicle miles traveled, speed, and vehicle type. Other mobile source emissions models include MOtor Vehicle Emissions Models (MOVES).

For more information on environmental analysis, visit EPA's model website (https://www.epa.gov/moves).

Benefit-Cost Analysis

Agencies should consider both the short- and long-term financial considerations of implementing ATM. Previous guidance and research highlights the possible benefits and cost components of specific ATM strategies. However, individual strategies are rarely implemented alone but rather introduced as a complement to a greater transportation improvement program. Specific tools and analytical approaches can help support the generation of valid benefit and cost estimates. FHWA developed an Operations Benefit/Cost Analysis Desk Reference⁽⁴²⁾ and the Operations Benefit/Cost Analysis Tool for Operations Benefit-Cost Analysis (TOPS-BC)⁽⁴³⁾ and User's Manual⁽⁴⁴⁾ to help guide practitioners in estimating benefits and costs of implementing various TSMO strategies, inclusive of ATM. The desk reference provides the ability to investigate the range of impacts based on similar previous deployments and includes default cost data for estimating overall life-cycle costs (capital, replacement, and continuing operations and maintenance).

ATM Application: FHWA sponsored a project to develop multiple simulation testbeds and transportation models to evaluate the impacts of CV dynamic mobility applications (DMA) and ATDM strategies. For the Chicago testbed, researchers modeled the ATM strategies of DShL, DLUC, dynamic speed limits, and ATSC. Some high-level research questions considered in the study within the broader context of DMA and ATDM included: Are ATDM strategies more beneficial when implemented in isolation or in combination? What ATDM strategy or combinations of strategies yield the most benefits for weather related operational conditions? What ATDM strategies or combinations of strategies conflict with each other? Which ATDM strategy or combinations of strategies will be most beneficial for certain modes and under what operational conditions? Which ATDM strategy or combinations of strategies will be most beneficial for certain facility types (freeway, transit, and arterial) and under which kind of weather related operational conditions? Which ATDM strategy or combinations of strategies will have the most benefits for individual facilities versus system-wide deployment versus region-wide deployment and under which kind of weather related operational conditions? Analysis, Modeling, and Simulation (AMS) Testbed Development and Evaluation to Support Dynamic Mobility Applications (DMA) and Active Transportation and Demand Management (ATDM) Programs: Evaluation Report for the Chicago Testbed, Report FHWA-JPO-16-387, 2017, https://ntl.bts.gov/lib/62000/62100/62176/FHWA-JPO-16-387__2_.pdf.

2.5 PROGRAMMING AND BUDGETING

Partnerships and collaborations are often essential to implementing ATM, particularly through the programming and budgeting process. Securing funding for transportation projects is highly competitive given the nature of limited and constrained resources. Federal policy mandates and guides many components of planning, programming, and funding projects. ATM strategies can be included within an improvement or long-range plan once an agency or project sponsor determines that it can complement or improve upon statewide, regional, or local goals. However, ATM strategies will have to compete with other projects to gain approval for funding.

The processes that comprise the programming elements of planning will differ from State to State and will entail the steps that agencies must undergo to select projects for funding. Project sponsors often develop a decision-based framework with financial considerations for implementation. States and regions, as represented by metropolitan planning organizations (MPOs), coordinate their efforts through the development of the long-range transportation plan, taking into consideration changes in overall demand and improvements to the transportation system. MPOs are required to develop short-range transportation improvement programs (TIPs) that can include select ATM strategies if those projects are estimated to have a high priority. States are also required to develop similar short-range plans, commonly known as a statewide transportation improvement program (STIP). Projects listed within a TIP have committed funding set aside for implementation.

ATM Application: The operational planning study prepared for Georgia Department of Transportation for Metro Atlanta, includes the ATM strategies of hard shoulder running, variable speed limits, queue warning, dynamic merge control, dynamic ramp metering, and variable/dynamic ramp closures. The study document outlines potential steps toward identifying potential funding sources. Potential sources identified include federal sources and categories, state funding sources, as well as local funding sources. Specific programs are discussed, and a matrix of potential projects and eligible funding sources provides direction to agency personnel and regional partners in identifying resources for future endeavors. Metro Atlanta Operational Planning Study, Georgia Department of Transportation, 2014, http://www.dot.ga.gov/BuildSmart/Studies/ManagedLanesDocuments/OPSFinalReport.pdf.

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