A digitally constructed highway segment is starting to come together outside San Antonio.
By Angie Schmitt
FM 1977, a short highway segment that is just three-tenths of a mile, is being reconstructed outside San Antonio. As part of the reconstruction, TxDOT is adding a shoulder. This is routine work for the agency, but the way this project is being built is anything but typical.
FM 1977 is a pilot for TxDOT as it charges ahead with 3D construction. The project will be entirely built using digital delivery. As Jacob Tambunga, TxDOT’s Digital Delivery Director, told attendees at FHWA’s Digital As-Built Webinar, all of the processes from design to inspection to asset management have to be reconsidered and refined.
The pilot is intended to be a learning process for both TxDOT and its private partners.
TxDOT has been moving toward paperless construction for a while now. Employees in all 25 of the agency’s districts have been trained to use a software platform that allows for 3D modeling. Last June, TxDOT put out word that the program would be the standard for all its project designs moving forward.
However, Tambunga said the agency is still adapting its processes to meet the standards of the digital era.
FM1977 is one of four digital construction pilots TxDOT is overseeing right now.
“We’re going to be a support mechanism for the contractor during construction,” Tambunga told listeners. “We want to make sure we can help this contractor get this project constructed while we gather information about what works well.”
TxDOT is still navigating a lot. For example, how will a paperless process affect inspection? The agency has a consultant helping them work through these issues and train employees. TxDOT has working groups looking at software issues, such as how to handle change orders and other process questions.
The agency is also involved with many committees and initiatives aimed at developing universal standards and overcoming other procedural hurdles. One of those committees is AASHTO’s Joint Technical Committee on Electronic Engineering Standards.
“We’re developing a data dictionary,” Tambunga said. “What do the words that we say mean? We need a very good definition, so that we are talking the same language.”
TxDOT expects that the hard work going into making process adjustments will pay off.
“One of the biggest benefits is we’re designing every square inch of a project with design intent,” he said. “And what that really does is it puts that responsibility onto that sealing engineer that everything that’s designed — number one — is safe — number two — is constructible.”
Another major benefit is greater accuracy in judging earthwork quantities, he said. 3D modeling reduces the need for costly change orders.
Historically, the agency has frequently “overrun and underrun our quantities based on the straight-line interpretation from our cross section,” he said. “We all know that the world isn’t straight lines. Using model-based quantities really does give us more accurate interpretations.”
Tambunga also said digital construction streamlines the entire process.
“With everyone getting busier and having less people, we really need to figure out how we’re going to be more efficient in our design and construction,” he said. “We really feel like utilizing models in the field is one of those ways.”
To that end, the agency has begun incorporating 3D models, and in some cases digital twins, from the outset.
“We’re going to start providing 3D models to all of our contractors once they get the job,” Tambunga said. “Every project that has geometry or needs cross sections will incorporate 3D modeling.”