Overview
North Carolina’s I-26 widening project stretches approximately 17 miles and included the demolition of five bridges along I-26 which were initially planned to require median crossovers with barrel separation for opposing traffic lasting two weeks per bridge. This was not an acceptable solution and NCDOT looked to Integrated Corridor Management (ICM) for additional options. The ICM strategy allowed for a full nighttime closure, rerouting traffic to the parallel arterials, and reducing the time needed for demo. Instead of ten weeks of closures on I-26, each bridge would be demolished in 3-4 nights. When the safety and construction cost benefits were identified, the contractor modified the construction plans to include ICM for construction, saving close to $700,000. Closing the interstate to live traffic has significantly reduced the risk to construction workers. Dispersion of the queue around the construction and onto the alternate route increases safety for all road users by reducing the likelihood of primary and secondary crashes.
In this case study you will learn:
- How NCDOT used Integrated Corridor Management on major bridge demolitions and construction projects
- How the ICM processes used existing field devices, such as CCTV cameras and Dynamic Message Signs (DMS), and installation of additional ITS devices on both the interstate and parallel routes and how dynamic trailblazer signs were installed as part of the ICM as a low-cost solution for arterial routing.
- How ICM has resulted in construction savings and improved safety during the I26 construction.
Background
The North Carolina Department of Transportation (NCDOT) is continually pursuing solutions for the transportation network that integrate technology and operations to improve safety and mobility. One such solution is the Department’s implementation of an Integrated Corridor Management (ICM) strategy to mitigate impacts of a large construction project on I-26 and expedite the construction project itself. ICM used for construction mitigation maximizes traffic throughput by leveraging the capacity of both the interstate under construction and the parallel arterial and reduces costs of construction.
The I-26 widening project stretches approximately 17 miles. The project included the demolition of five bridges along I-26 which were initially planned to require median crossovers with barrel separation for opposing traffic, each closure lasting two weeks per bridge. This was not acceptable to NCDOT, so a second and more safe option was proposed to deploy rolling roadblocks. This would incur more costs and increase the time required to complete the demolition. Meanwhile, NCDOT decided to deploy ICM as a strategy for incident management in the construction zone. The key players, including the Division Engineers and Resident Engineers, recognized that using the incident ICM strategy could be the solution to safe and efficient demolition of the bridges. The ICM strategy would allow for a full nighttime closure, rerouting traffic to the parallel arterials, and reducing the time needed for demo. Instead of ten weeks of closures on I-26, each bridge could be demolished in a matter of 3-4 nights. When the safety and construction cost benefits were identified, the contractor modified the construction plans to include ICM for construction, saving close to $700,000 in construction costs. Bridge demolition and corresponding ICM activations began in March 2021. The agencies’ experience with ICM has been so positive that it is deployed frequently during construction activity beyond the expected bridge demolition.
TSMO Planning, Strategies and Deployment
The ICM strategy for construction includes a full closure of I-26 in the work zone. This full closure requires an advanced level of traffic management, including use of existing field devices, such as CCTV cameras and Dynamic Message Signs (DMS), and installation of additional ITS devices on both the interstate and parallel routes. The DMS are used to direct motorists off the interstate and onto the selected alternate route. The designated route is based on the closure location along the I-26 corridor. Dynamic trailblazer signs were installed as part of the ICM as a low-cost solution for arterial routing. The signs are used to guide motorists along the alternate route with a straight arrow indication, or, when they have navigated around the closure, direct them back to I-26 with a turning arrow indication. Shifting additional traffic to the alternate route increases the demand on the signalized arterial roads. The ICM strategy implements specialized signal timing plans focused on improving throughput. When the new signal timing plans are activated, an Incident Management Assistance Patrol (IMAP) responder or other NCDOT representative leads the initial platoon along the alternate route to ensure that all traffic control devices are in place and validates the travel time. Most closures take about two to four nights in each direction and last from 8:00 PM – 6:00 AM.
Communications Planning and Execution
The project limits of the I-26 Widening Project stretch across two counties and impact multiple agencies. This footprint provided for potential complications from the beginning. To address this complex partnership, key partners developed and signed an Open Roads Memorandum of Understanding (MOU). This legally non-binding document outlines the general rules of engagement between partners and formed an Open Roads team to foster collaborative communication. The team includes about 200 people from the transportation and construction industry and other institutions like schools and hospitals who could be affected by the closures and alternate routing.
The communication timeline for each activation follows these steps:
1) The Contractor alerts the Resident Engineer of the schedule for bridge demolition.
2) The Resident Engineer submits an announcement to the NCDOT PIO to include the limits, time of day, and duration of the closure.
3) The Regional Traffic Incident Management (TIM) Coordinator sends an announcement to the Open Roads Team about three to five days before the closure.
4) The Regional ITS Engineer sends out a link to the live video sharing stream through Microsoft Teams the day before the closure.
The members of the Open Roads Team then distribute information to other key partners in their agency and invite them to the Microsoft Teams live camera feed to observe the closure and activity on the alternate routes. Public communication takes place through NCDOT’s communications department, which notifies the public of the closure through media releases and social media posts.
Additional internal communication takes place at weekly construction update meetings. A portion of these meetings are dedicated to closures and ICM activations. This open communication regarding schedule and construction activities helps all partners keep well informed of the project status. It is also an opportunity for the construction contractors to request additional closures for other construction activity.
Outcome, Benefit and Learnings
The I-26 Widening Project ICM Deployment has generated two primary benefit categories: safety and efficiency. Closing the interstate to live traffic has significantly reduced the risk to construction workers. Dispersion of the queue around the construction and onto the alternate route increases safety for all road users by reducing the likelihood of primary and secondary crashes due to unexpected traffic patterns or queues on the interstate.
Additionally, the efficiency of the construction project is improved by reducing the time required for bridge demolitions and other construction activities. The original traffic management plan options each projected two weeks of closures per bridge. The reduction in time commitment from two weeks to three or four nights per bridge has resulted in a savings of nearly $700,000 in construction costs alone. Congestion through the work zone is reduced due to the elimination of onlooker delay thus saving time for motorists. The construction contractor has also identified additional cost savings through more efficient resource delivery to the work zones.
Lessons learned from the I-26 ICM project are being used to continually improve deployments. NCDOT is considering the effectiveness of dynamic trailblazer signs compared to higher visibility or more effective signage to route traffic along the alternate route. The I-26 ICM has also led to observations of the benefits of signal timing adjustments and tracking travel time through the alternate routes. Continued testing of various ICM routes provides NCDOT the opportunity to observe how the rerouted traffic behaves. In some cases, motorists choose to follow their GPS once they are routed off the interstate and continue along different routes. The takeaways from these nighttime observations help with planning for peak hour ICM activations. With each activation, NCDOT improves upon efficiency for the next closure and for future construction projects in North Carolina.