Active Traffic Management Feasibility and Screening Guide
Chapter 7. Next Steps
Completing the ATM feasibility and screening process, as discussed in the previous chapters, is just the beginning. At this juncture, agencies can use the results from the screening process for two general directions:
This chapter does not provide guidance on developing a Concept of Operations for ATM or for incorporating ATM in the regional or agency transportation planning processes; several references and examples are available to guide the practitioner in this regard. Rather, this chapter highlights a few key issues that will need to be addressed during these next steps, the knowledge of which will be of use while applying the initial screening guidance.
7.1 Stakeholder Involvement
Engaging with stakeholders as part of the screening process is discussed in Chapter 2. This is a continuing process, and regardless of which direction an agency takes, the number of stakeholders and the need for interaction will increase. Moreover, the driving public will become an important stakeholder requiring public outreach and education activities to help ensure they fully understand the ATM operational concepts.
7.2 Performance Measures
Performance measures indicate how well the transportation system is performing and are inextricably tied to operations objectives. Developing performance measures is an integral part of the objectives-driven, performance-based approach to planning (as shown in previous Figure 1). The performance measures selected should provide adequate information to planners, operators, and decision-makers on progress toward achieving their operations objectives.(2)
ATM-related performance measures will likely be necessary for both the planning process and Concept of Operations. Should detailed analyses be performed via simulation, the performance measures should guide the modeling process. Performance measures will also be critical to monitoring the performance of the implemented ATM strategies, thereby allowing operators to make tweaks to implemented strategies to maximize benefits they offer. Moreover, the ability to expand coverage of ATM strategies may largely hinge on the ability to both monitor ATM strategies and demonstrate that strategies work toward meeting regional transportation goals.
A number of potential measures of effectiveness are identified in the literature. The Active Traffic Management Guidebook (4) identifies the following examples of performance measures used in European ATM deployments:
The Guide for Highway Capacity and Operations Analysis of Active Transportation and Demand Management Strategies (47) recommends four measures of effectiveness for evaluating the achievement of one or more ATDM objectives. These measures, as identified in the reference, are computed across all of the scenarios to obtain overall results:
Another ATM performance measure of great importance is safety. Potential before and after performance measures in this regard include the following:
7.3 Conformance with Regional Intelligent Transportation System Architecture
The initial activity shown in Figure 2, the Systems Engineering Vee Diagram, is the "Regional ITS Architecture." FHWA Rule 940 (23 CFR 940) requires ITS projects that are funded, in whole or in part, with the Highway Trust Fund to conform to the National ITS Architecture and standards. The rule states that "conformance with the National ITS Architecture is interpreted to mean the use of the National ITS Architecture to develop a regional ITS architecture, and the subsequent adherence of all ITS projects to that regional ITS architecture."
The National ITS Architecture identifies a series of transportation services for which transportation systems apply. These transportation services are addressed through 95 unique Service Packages. A Service Package is a group of different subsystems and communication flows needed to deliver a desired transportation service. Service Packages can work separately or in combination to address the real-world transportation needs and desires identified through traditional planning activities. Service Packages directly related20 to the ATM strategies are listed in Table 16. Three of these—ATMS22: Variable Speed Limits, ATMS23: Dynamic Lane Management and Shoulder User, and ATMS24: Dynamic Roadway Warning—were recently created to support ATM and included in the National ITS Architecture as part of Version 7.0 (released in late 2013). Accordingly, while not necessary for the ATM screening process described herein, it may be necessary to update the Regional ITS Architecture to include these ATM-related Service Packages as the systems engineering process continues such that the proposed ATM system, as subsequently documented in the Concept of Operations and Requirements, does indeed "conform" to Rule 940.
7.4 Regulations and Manual on Uniform Traffic Control Devices Standards
The potential for changes in legislation to support certain ATM strategies (dynamic shoulder lanes, dynamic speed limits/displays) has been previously noted. ATM signage and procedures, particularly for dynamic lane assignment and possibly dynamic speed limits, as used in Europe and in the initial ATM implementations in the United States are not currently described in the MUTCD. This is particularly the case for DLA displays to alert drivers that a lane is closed downstream and that they should merge left or right.21
Steps for experimental approval should be taken when a project timeline is set to ensure approval when the system will be activated. Per the MUTCD,(49) "a successful experiment is one where the research results show that the public understands the new device or application, the device or application generally performs as intended, and the device does not cause adverse conditions. The 'experimenter' must evaluate conditions both before and after installation of the experimental device and describe the measurements of effectiveness (MOEs) of the safety and operational benefits (e.g., better visibility, reduced congestion)." The request for experimentation should originate with the agency and be sent to the FHWA MUTCD Team with a courtesy copy to the local FHWA Division Office. The FHWA must approve the experiment before it begins. All requests should include the following information:
FHWA recently completed a project to evaluate ATM sign displays and to identify potential gaps in the MUTCD in this regard. The project is completed, but the findings and recommendations are still being reviewed by the TMC Pooled Fund Study and FHWA, and have not been released to date.
Shoulder lanes and junction control strategies may also require FHWA approval for design exceptions and modifications once a shoulder is turned into a travel lane. These may include the following:
Deploying dynamic shoulder lanes and junction control may require expanding the roadway footprint for widening the shoulders and to accommodate pull-out refuge areas. By moving traffic closer to the edge of the right-of-way, noise might increase near the right-of-way. In these circumstances, developing environmental assessments and/or environmental impact statements in accordance with the National Environmental Policy Act (NEPA) process might be necessary; this is an activity that should be included in the cost estimate.
7.5 The Future
One of the early activities in the ATM feasibility and screening process is reviewing recent literature on ATM strategies—from the United States and abroad—to determine whether any new approaches, guidelines, and/or standards have come to light that might impact or otherwise influence the screening process as described herein and any subsequent design activities. There has been an often rapid evolutionary path in the design and operational approaches for several ATM strategies, such as sign displays and layouts, the spacing of sign gantries and supports, operating algorithms and automated decision support mechanisms, and the associated real-time data needs. Moreover, several ATM strategies are in their relative infancy in the United States, and there will undoubtedly be many lessons learned and new requirements (e.g., MUTCD standards for lane control and dynamic speed displays, updates to the National ITS Architecture, and use of automated speed enforcement) as ATM matures in this country. Such future developments will impact not only the feasibility screening but also ATM design and operations. It is most important that the practitioner be aware of any such future developments when looking at potential ATM strategies and the optimum roadway locations.
There is also the long-term future of a connected vehicle environment and its potential impact on ATM. There are many possibilities in this regard—for example, data that permits better short-term predictions of congestion and safety concerns and real-time environmental data that are used to dynamically change speed limits and signal timing to minimize emissions. Who knows, but in-vehicle displays and automated vehicles may completely eliminate the need for ATM infrastructure signs altogether sometime in the distant future. But that is the subject of another Guidance document years from now.
20 Other Service Packages support ATM operations, including, but not limited, to, surveillance, incident management, road weather data, work zone management.
United States Department of Transportation - Federal Highway Administration