GIS Keeps North Carolina DOT Working Efficiently with Transportation Project Prioritization

A suite of GIS tools is enabling North Carolina DOT to dramatically reduce the time and effort needed to produce its long-term Comprehensive Transportation Plans.

With the federal passage of the Moving Ahead for Progress in the 21st Century Act in 2012, state departments of transportation and metropolitan planning organizations were required to follow a more comprehensive performance-based approach to decision-making. Performance-based planning is built around defining the goals and objectives a state or region wishes to achieve and then identifying the strategies and investments to realize those goals. Central to this approach is that decisions should be data driven, and performance should be continually monitored to ensure the success of the investments in realizing the stated goals.

While this was a new language for many transportation agencies at the time, the North Carolina Department of Transportation (NCDOT) was ahead of the curve in meeting these requirements. The Strategic Transportation Investments law was already under consideration in North Carolina, and with the law's passage in 2013, it set in motion a process to ensure that NCDOT used funding efficiently and effectively to enhance infrastructure while supporting economic growth, job creation, and a higher quality of life.

NCDOT is composed of 14 geographic divisions, with 18 rural planning organizations, and 19 metropolitan planning organizations, all required to collaborate to develop the state's long-range Comprehensive Transportation Plan (CTP) and the State Transportation Improvement Program (STIP). Rapid growth in North Carolina during the turn of the last century—1.4 million people added between 1990 and 2000—led to greater transportation demands to keep up with the growth and greater demands for a more strategic and transparent process for the state's infrastructure investments.

Previously the processes for developing these plans were often inconsistent and ad hoc, focused on short-term rather than long-term needs, and often shortchanged the statewide needs over local priorities. Instead, the Strategic Transportation Investments law sought to change these processes and place greater emphasis on developing a formalized outcome and data-driven process, which also involved greater collaboration between NCDOT and its stakeholders.

This led to the current six-step process that NCDOT utilizes for its project delivery cycle, from planning to construction. Three of the steps facilitate development as far as the design stage: Planning, Prioritization and Programming, and Project Development and Environmental Analysis.

Step one: Develop the publicly available CTP, a statewide transportation vision for the next 30 years that contains a multimodal strategy to identify transportation system improvements necessary to meet future mobility demands. The CTP represents the long-term vision for how the transportation network should evolve to serve the area's residents and employers, optimizing such agreed-upon values as safety, system reliability, economic development, and environmental preservation.Develop the publicly available CTP, a statewide transportation vision for the next 30 years that contains a multimodal strategy to identify transportation system improvements necessary to meet future mobility demands. 

Step two: Identify the construction funding and the commitment to schedule and construct the transportation projects through STIP, a 10-year state and federally mandated plan. This project prioritization and selection process to develop the STIP is driven by a geographic information system (GIS)-based application called SPOT Online, which gives projects a score and an estimated cost for each project to help manage a project selection process driven by data.

Step three: Fund projects and assess their environmental impacts in Project ATLAS (Advancing Transportation through Linkages, Automation, and Screening), which was developed as a means of guaranteeing project development timeframes.

These first three steps are served by GIS-based applications that use Esri products and were developed on behalf of NCDOT by the North Carolina Department of Information Technology-Transportation (NCDIT-T). A fundamental component of the work carried out by NCDIT-T is the standardization of both the data and the data handoff at the end of each step: the data used within the CTP, then SPOT Online, and, later, ATLAS has a common baseline.

All three application teams (CTP, SPOT, and ATLAS) are unified under one management umbrella to coordinate the IT support for the project delivery pipeline and coordinate the utilization of the same enterprise data and external web services. As Eric Wilson, NCDOT's GIS manager related: "In 2017, NCDOT had clearly identified that utilizing various 'historical flavors' of the same data for impact screening across the project delivery pipeline was causing serious problems in the analysis of costs and awareness of impacts, and it tasked us with tightening that process up."

"The bigger picture is the use of GIS data," says David Chrest, a senior GIS analyst from the Timmons Group who works within the NCDIT-T.

"A main goal is the use of a common geodatabase. The data within that geodatabase is multifunctional, and we provide a suite of custom tools for analysis. The aim of the CTP group within NCDOT is to come up with data-driven requirements, which are underpinned by the exploitation of the geodatabase's analytic capabilities. The schema that underlies this is designed for intakes of recommendations across multiple modes—highway, bicycle, pedestrian, multimodal paths, public transportation, and rail.

"The GIS unit here within the NCDIT-T updates the LRS (Linear Referencing System) for the roads within its database every quarter. That LRS is boiled down to individual road characteristics and then processed further to simplify segmentation so that it's of more practical use to the engineers who are inputting information for their CTP submissions.

"The main feature classes for information intake are the road structures, bridges, rail tracks, and rail and public transportation facilities. There is a huge array—over 150—of supporting feature classes. Around a third of those are environmental data, designed to help with the best possible decisions over recommendations."

The use of a unified database, says Chrest, addresses a historical issue whereby the use of data that was not from a common source was skewing outcomes when project recommendations were being formulated.

A complete CTP is generated every 5 to 10 years, and it is not a prioritization list. Rather, it is a compendium of all recommendations for possible improvements to the transportation network. Projects selected to go into the CTP are not done algorithmically but rather are the consensus of transportation planners and engineers from the DOT and the various regions for that area plan.

To prepare a project report for eventual incorporation into the CTP, an engineer defines on-screen the relevant geographic area and then goes on to complete several fields, such as road type (freeway, expressway, and so on), using a series of drop-down menus. As the process continues, a great deal of field mapping/automatic population occurs.

For example, the Capacity Calculation Tool provides—instantly—average annual daily traffic volumes for different road types. Such calculations used to be a manual process that involved looking up values on physical tables. The Long Text Tool enables the engineer to add larger volumes of text that will then be automatically formatted when the final report is generated.

In addition to the uniformity and accuracy that is imparted, the cumulative time savings are notable; this is a product reflective of the level of programming carried out by the NCDIT-T team. The Inventory Table Tool, for example, reduces to just 20 seconds a population exercise which, before the use of the geodatabase, would have taken a month.

Feedback on the application's ease of use has depended on individual experience levels, says Chrest.

Most of the feedback so far has been great. In other cases, it's driven by how quickly engineers can learn to use the geodatabase. Some of them, for example, have been surprised to see drop-down menus when they click on a domain because, in the past, all they've been used to is just typing in data.

"We have had some pushback that some things used to be faster, but that highlights the issue of standardization. Someone might think that they have a 'quicker' way of doing something, but replication of that work by anyone else then proves to be impossible because it was never done the same way twice. That's not good in terms of consistency and transparency, which is what we're aiming for here."

The effort to automate many of the processes that go into creating the CTP started in 2017.

"The downstream ATLAS project was using a lot of analytic tools that were attractive to the CTP team, who wanted them on their own desktops for use at the regional level," said Wilson.

"The first release of the database to engineers took place in January 2019, and by October 2021, we had something to show in terms of the first CTP document generated using the new processes.

"What we've created worked very well from the outset. We're now at the very fine level—there's lots of paying attention to detail to make things work better."

It took two years to bring together a CTP using the new tools, said Wilson. The goal is to reduce that to between 6 and 12 months. That would put NCDOT even further ahead of the curve.