For decades, the AASHTO Policy on Geometric Design of Highways and Streets (the Green Book) has been a foundational guidance document for determining the geometric features of our nation’s highway system. This guidance is built upon documented research and general assumptions of how geometric elements affect system performance. The Green Book continues to provide the content that is the basis for the design standards that are adopted and deployed nationally as well as at a state and local level and drives a significant portion of highway investments.
As transportation agencies look for ways to maximize the effectiveness of this highway infrastructure, operational strategies are becoming broadly recognized as necessary and cost effective in accomplishing system performance objectives. These strategies often bring with them the ability to affect driver behavior, with direct connection to how drivers react to the conditions they encounter along their route, both in terms of real-time non-recurrent events, as well as static features such geometric elements. These strategies rely upon a different type of infrastructure and provide the ability to influence and, in some cases, redefine traditional geometric elements.
Ultimately to support decision-making processes, various analysis tools and methodologies continue to be developed and refined to better align with the needs and performance expectations of the users of the highway system, as well as to reflect new strategies available to system providers. These include work zone safety and mobility improvements resulting from 2004 FHWA Work Zone Rulemaking and advancements in the Manual on Uniform Traffic Control Devices to address the integration of intelligent transportation system and other future technologies. The latest efforts of the second Strategic Highway Research Program (SHRP 2) developed enhanced methodologies to assess safety, capacity, and reliability that lay the groundwork for considering cross-cutting strategies that incorporate both operational and geometric features. These tools are now in early implementation phases across the country.
These three aspects when considered together drive the initiative for a formalized transportation systems management and operations (TSMO) program that goes beyond operating efficiency to providing the best way to develop, manage, and operate transportation networks and infrastructure. In support of this comes the need for a new perspective on how we look at and consider highway infrastructure, and a new way to think about “standards” associated not only with infrastructure, but also with system management capabilities as necessary components to accomplishing performance.
The Strategic Plan of the AASHTO Highway Subcommittee on Transportation Systems Management and Operations (TSMO Subcommittee) includes eight goals, five of which could be supported by the proposed project: (1) encourage adoption of proven TSMO concepts and strategies, (2) support DOTs in implementation of system performance measurement and management to tie in with TSMO, (3) develop and evolve a workforce that is fully capable of accommodating and expanding TSMO through development of needed skill sets and training, (4) continue to make the business case for TSMO, and (5) build upon and expand the use of the capability maturity model to improve agency TSMO capability and expertise. At their June 2015 meeting, the TSMO Subcommittee expressed their overwhelming support for the proposed project and their intent to adopt the resulting product(s) through the AASHTO balloting process.
The objective of this research is to develop the first edition of “Operational Standards for Highway Infrastructure,” a proposed AASHTO publication developed under the auspices of the TSMO Subcommittee.
It is expected that the Operational Standards will identify operational strategies and associated elements (e.g., traffic incident management, active traffic management, traffic signal coordination, vehicle-to-infrastructure equipment) that should be considered “standard” features of the highway system. This includes both urban and rural aspects of the highway system taking into account the operational condition of a facility and the system management capabilities necessary to meet designated performance objectives. The Operational Standards should also be useful in innovative design processes (e.g., performance-based practical design, context sensitive solutions) by coupling geometric and operational improvements to most effectively meet the project’s purpose and need within a constrained budget.
NCHRP Project 20-07/Task 392, “Transportation System Management and Operations Standards for Highway Infrastructure,” was approved at the AASHTO Annual Meeting in September 2015 and will develop the scope for the proposed guide. The objectives of that project are to (1) investigate the focus for, potential use and topics to be included within the context of an “Operational Standards for Highway Infrastructure” document and (2) develop a roadmap for conducting research needed in order to develop such a document. The full scope of work is available on the TRB website.