We live in a society where cameras are everywhere. You may have noticed cameras along the sides of freeways and at interchanges while you’re driving. Closed circuit television (CCTV) systems have been used for many years on highways to monitor traffic flow and verify vehicle crashes. These devices are part of an Intelligent Transportation System (ITS).

In Charlotte, N.C., DRMP is designing roadway, bridge, and ITS, for the $83 million I-485 Widening from I-77 to Rea Road project. This job is a North Carolina Department of Transportation (NCDOT) and North Carolina Turnpike Authority (NCTA) design-build project. It involves the design and construction of separated toll lanes on a controlled access facility, beginning west of the I-77/I-485 interchange in Mecklenburg County, following existing I-485 for approximately 20 miles, ending east of the interchange of I-485 and U.S. Route 74. 

This section of I-485 is one of the most congested roadways in North Carolina, averaging between 110,000 and 135,000 vehicles per day. 

WSP USA, the lead design firm on this project, contracted with DRMP to lead the ITS portion of the design.  DRMP prepared the plans and Special Provisions for three-fourths of the ITS work (about 15 miles) and WSP did one-fourth of the work.  I’m the lead designer for the ITS on the project.

My work on this project is primarily comprised of creating two communications systems – one new toll and one expanded ITS – to connect the existing, relocated, and new ITS devices as well as to incorporate the new All Electronic Tolling (AET) locations into the existing fiber infrastructure in the area.  The ITS devices include closed circuit television (CCTV), microwave vehicle detection (MVD), and dynamic message signs (DMS). 

Part of what makes the system intelligent is being able to transmit transportation information to a manned centralized traffic management center to be able to collect, analyze, and act on it.  The communication networks being added under this project tie back to the Metrolina Regional Transportation Management Center (MRTMC) in Mecklenburg County.  From here, someone monitors traffic conditions using ITS devices, and the toll information is transmitted to NCTA for use.

We’re putting in the infrastructure for the communication networks that tie the ITS devices to the MRTMC so the information can be useful. There are basically two pieces of design work – the communications infrastructure and then the ITS devices design.  Once the infrastructure along the corridor is designed, the best location for each of the ITS devices is selected.

One of the things I did on this project was design the general architecture of the two communication systems along the corridor – basically how the information flows between the devices and the MRTMC for both communication networks.  The ITS communications network was already in place, and our project just extended this system.  The Toll communication network was a new system.  

I have always focused more on the infrastructure for the fiber optic network and less on the fiber design in the past.  I learned a lot putting together the architecture for this project.

Benefits of ITS

The concept of ITS is nothing new.  It’s been around for decades and has evolved over time with the advancement of technology.  ITS strives to improve transportation safety, reliability, and mobility by monitoring traffic conditions, including accidents. It gets real-time information back to the public and emergency personnel.

The most recognized way to get information to the public is through the use of dynamic message signs (DMS).  DMSs are electronic signs on the highway that provide drivers with real-time traffic alerts and information. The larger signs can be used to provide travel time information, traffic crash alerts, direct traffic to detours, and other roadway safety alerts. 

A lot of this information is seen through the CCTV system.  The MRTMC personnel use the CCTV system to verify the location of accidents and relay them to emergency personnel.  For stalled cars on the side of the road or drivers needing help, the MRTMC can coordinate with Incident Management Assistance Patrol (IMAP) personnel to get aid as soon as possible.  In the case of extensive congestion or a significant accident, they can also use incident management plans to provide detour routes along the corridor when appropriate.

In addition to the information seen on the CCTV system, there is data collected through microwave vehicle detection devices (MVDs) used to assist with the decision-making process at the MRTMC.  This data includes vehicle counts, lane occupancy, and speed data. MRTMC personnel can use this data to verify information that may or may not be able to be seen on the CCTV system.  These same sensors are used by NCTA to evaluate the roadway conditions and determine the value of the express lanes.  Because these sensors have multiple uses along the corridor, there are a lot of them across this project.   

Only Second Express Lane System in North Carolina

There are no other tolls on I-485 around Charlotte.  This 20-mile section of road will be a standalone expressway system that will be tied into the NCDOT/NCTA system. It’s a system with multiple ITS devices working together with locations that are interdependent with the other devices.  This is only the second expressway in North Carolina to have separated tolled express lanes.

The first expressway design done in North Carolina was for I-77, which was under a public-private partnership, to leverage private funding to build and open the project sooner than with state funding.  The I-77 project was still in construction during the design of this project, therefore, NCDOT/NCTA were still unsure of how everything would actually work.  This is the first ITS design of its kind in North Carolina for an NCDOT/NCTA project.

This ITS project was broken down into two parallel systems: general-purpose lanes and express lanes. The general-purpose lanes are what you would see on any freeway or highway for all traffic. The expressway lanes are tolled lanes (or managed lanes) in the center of I-485 and are separated from the general-purpose lanes by plastic tubular markers. With the traffic going in the same direction, the tubular markers are a safe way to separate the two systems and are safer than concrete barricades because they are designed to fall over and pop back up if a vehicle hits them.

The tolled express lanes are just another way to try and keep traffic flowing. If the general-purpose lanes are congested, you can pay and use the express lanes.  The goal is to give the driver an alternative with a reliable trip time.   At each end of this 20-mile project, there will be a DMS sign that will specifically be used to give speed and travel times information for the corridor for both the tolled expressway and the general-purpose lanes.   This information helps drivers determine if the toll lane fees outweigh the delays associated with the general-purpose lanes.   

This roadway will use a variable toll system in which toll rates fluctuate during peak and off-peak hours based on need. The smaller DMS signs on this project show the variable prices of tolls, like the small DMSs used for travel time information.  That’s part of the reason there are MVDs all along the corridor. The vehicle detection is not only counting cars it’s looking at speed data. The slower the general-purpose lanes are going, the more value there is for the express lanes.

Coordination

DRMP coordinated directly with the NCDOT ITS section and NCTA for approval of the plans.  We also coordinated with the Metrolina Regional Transportation Management Center (MRTMC) for existing fiber architecture, existing equipment information, and proposed routing using existing fiber. We also had to coordinate with numerous other agencies and consultants on this project.

Because all the components of this project are inter-related, we coordinated with the designers for AET, roadway, pavement marking, and signing.  One of our main goals was to create the communications for the toll system.  Our design connected the AET equipment, so coordinating with the AET designers was crucial. 

Our design also addressed power needs for the ITS devices.  We coordinated with Duke Energy, Pineville Power, and Union County Power to identify service points for all the new equipment.  

I had to coordinate with the sign designer as well. The DMS signs, both large and small, were incorporated with the overhead sign designs for placement.

This is a big project that involved getting two different communications systems designed along one main trunk line and then back to one central location.

This particular ITS project for I-485 is actually my first time doing ITS design for tolled express lanes.  The infrastructure we’re talking about is the same whether you do it on a signal system or a toll road, or in this case tolled express lanes. 

I’ve been working on city signal systems for more than 20 years. They connect signal, CCTVs, and DMS at times to centralized traffic management centers as well. 

I recently was the project manager for the Elizabeth City signal system.  For the I-485 project, we incorporated the AETs, which I had designed previously for the Monroe Bypass, and the MVD sensors.   I learned a little bit more about the MVDs during this project because there were so many on this job. 

The cool part about this particular job was to be able to take my experience from the last 20 years working on ITS and apply it to a new type of project.