When the North Carolina Department of Transportation (NCDOT) wants to determine the feasibility of a new project, it first needs to arrive at a cost estimate, sometimes years before a single survey stake goes in the ground. In the past, those estimates were built on historical unit costs and educated guesses. For routine projects in stable conditions, that approach might have worked well enough. But unforeseen circumstances, like the supply disruptions and construction inflation during the COVID-19 pandemic, combined with new legal requirements and the particular qualities of the site, often mean these estimates fall short. A project budgeted at $2 million may arrive at the design phase with a $20 million price tag. This is a scenario that express design aims to help resolve.
A Faster Path to a Defensible Estimate
An express design is a rapid, low-level 3D design that provides a more reliable estimate of a proposed project’s eventual costs. The program was developed with rapid turnaround in mind, and a typical express design can be completed in six to 12 weeks. It uses state-plane lidar data rather than a conventional survey, which means it carries an accuracy range of roughly plus or minus six inches. While that level of detail is sufficient for programming purposes, it’s not a substitute for final design. What it produces is a basic horizontal alignment and vertical profile, a simplified 3D model, and enough geometry to generate meaningful quantities for pavement, earthwork, drainage, and structural element needs.
From those quantities, NCDOT applies unit costs and estimate utility relocation and right-of-way impacts. The result is a cost figure that is far more grounded than a historical average, one that agencies can use with confidence when they submit projects for prioritization and when those projects are added into their statewide transportation improvement program (STIP).
In North Carolina, every project that makes it into the STIP goes through this process. That's hundreds of projects per year across the state, covering everything from intersection improvements and bridge replacements to interchange reconfigurations and interstate widening.
More Than a Spreadsheet Exercise
Cost accuracy is the primary objective, but transportation projects respond to specific community needs. Each express design includes basic traffic and safety analysis, with crash data pulled and reviewed for every project. That analysis confirms that the proposed improvement addresses the stated purpose, whether that's a safety correction, a congestion reduction, or a pedestrian access improvement, before any estimate is finalized.
Stakeholder engagement is also built into the process. The communities and agencies that nominated the project have the opportunity to confirm that the design intent matches what they asked for. That early alignment reduces the risk of expensive course corrections later.