APPENDIX A: WHITE PAPER ON ATM IN WORK ZONES

INTRODUCTION

Construction work zones can limit the ability of the traveling public, emergency response vehicles, and construction crews to safely negotiate and respond effectively to the current traffic conditions. New and developing technologies in work zone management are enhanced by the capabilities of ATM for nonrecurring congestion scenarios. Agencies are deploying ITS to help manage traffic in and around work zones more efficiently (Ullman et al. 2014). This approach is often referred to as smart work zones (SWZ) where the use of these technologies helps reduce congestion, improve reliability, support freight/goods movement, and improve safety on the approach to and within the work zone. The basic characteristics of a SWZ include the following:

• Real time: SWZs gather and process traffic flow information in real time, regularly giving up-to-date information to motorists.
• Portable: SWZs are portable and installable in different destinations.
• Reliable: SWZs provide correct and reliable information.
• Automated: SWZs run in a computerized system with little supervision by human operators (Pant 2023).

The information gathered and analyzed for the deployment and operation of SWZs comes from various sources such as field sensors, third-party data, and available closed-circuit television data. This information notifies the roadway user of current conditions to enable more accurate travel choices and reduce traveler frustrations.

STATE-OF-THE-PRACTICE

ATM strategies successfully deployed in work zones include queue warning systems, dynamic lane merge systems, dynamic shoulder use, lane controls, real-time traveler information, and VSL systems. Existing ATM infrastructure can be adapted for work zone usage to convey information thereby reducing the need to install/move temporary equipment.

CONSIDERATIONS AND IMPACTS ON ATM

Implementing ATM strategies internal to work zones can be a complex challenge. The implementations must accommodate the traditional impacts of work zones (i.e., limited space and ingress/egress considerations) while additionally ensuring robust preplanning and perhaps most importantly, data availability for both real-time operations and assessments.

In terms of planning, ATM implementations in work zones must account for the physical movement of the work zone. Many states have contracting requirements for nighttime work zones that must be completely dismantled for daytime traffic operations. This requirement is most applicable to interstates. The need to assemble and disassemble not only the work zone, but the ATM implementation requires additional time on both ends. Contractors must be fully engaged with the supervising agency to ensure that this process is completed successfully. Law enforcement must be advised of the strategy implementations to ensure they understand how to enforce the work zone safely and effectively. Blue-light move-over laws can also significantly interfere with the operations of an ATM strategy before or within the work zone.

Data needs are a key element. Knowledge of all lane closures is necessary, including detailed location and timing information as well as traffic volumes, classifications, and speeds. Many of these systems update on a 5-minute or less time interval to ensure that changes in traffic conditions are detected quickly. Data must be collected, analyzed, and pushed to roadway devices quickly to be effective. The potential for rapidly changing conditions internal to work zones can mean that some systems operate on an even faster (e.g., 2-minute) update time interval. Additionally, the data are key for a continuing assessment of the strategy and its continued effectiveness on a routine basis—generally daily for work zone implementations.

CASE STUDIES

This section describes several case studies that highlight the incorporation of ATM into major work zone operations.

I-35 Central Texas Reconstruction

An example ATM work zone strategy is end-of-queue warning systems that alert travelers to upcoming congestion. The TTI created, refined, and expanded a traveler information system supporting the Texas DOT’s (TxDOT’s) goal to keep motorists informed of slowdowns and other potential mobility challenges during construction along the I-35 work zone in Texas (Brydia 2017). The automated system consists of networked sensors that detect and measure traffic speeds at multiple locations within the area of a potential queue. The system then communicates speed data to a processing unit to assess whether the speeds at one or more of the sensors indicates that a traffic queue has formed, determines an appropriate warning message to display to motorists approaching the queue, and communicates that message to one or more portable changeable message signs (PCMS) deployed as part of the system. These data provide travelers using I‐35 with accurate and comprehensive real-time information about current conditions. This information also provides recommendations to TxDOT and contractors regarding equipment placement and staffing needs.

Seminole Expressway in Florida

The FDOT also adapted ATM technology for use on a resurfacing project along the Seminole Expressway. The Motorist Awareness System includes an automated queue warning system, Waze^© application sensors, portable traffic sensors, and SWZ PCMS boards. The system provides real-time warnings of conditions ahead including STOPPED or SLOWED SPEEDS X MILES AHEAD. The navigational application sensors delineate the work zone boundaries with WORK ZONE BEGIN/WORK ZONE END alerts to Waze^© or Google^TM in real time (FDOT 2023).

RELEVANCE TO KEY CONCEPTS

Table A-1 summarizes the relevance of work zones to the major topic categories of the ATM guide. This matrix helped guide the inclusion of work zone content in the final guide.

Table A-1. Relevance of Work Zones to the ATM Guide Topic Categories.

CHALLENGES AND ENABLERS

Challenges for work zones includes conveying important information to roadway users in real time to allow for more effective and efficient decision-making such as expected delays and alternative routes. As new technologies become available, the need for public outreach is critical.

OUTSTANDING ISSUES AND MAJOR GAPS

Some of the issues and implementation considerations of queue warning systems may include but are not limited to the following:

• Advance notification of changes in lane configuration.
• Implementation plans based on expected queues and recent traffic volumes.
• Queue analysis procedures.
• Availability/usage of third-party data for analytics.
• Familiarity of contractors with systems and placements.

• Ongoing costs for operations and maintenance.
• Public education and outreach.
• Law enforcement awareness and incident response.
• Incorporation into construction plans at the design stage.

KEY REFERENCES