By BECKY GILLETTE
Wouldn’t it be nice to actually see how a road is going to look before building it? What if you could anticipate problems before encountering them in the middle of construction, thus avoiding delays that cost time and money? With the use of modern three dimensional computer-aided design and drafting (CADD) programs, engineers can come close to achieving that by being able to see the project in 3D on the computer screeN.
“The world of technology is changing and MDOT has to change with it,” said Gregory Geno, a CADD engineer for the Mississippi Department of Transportation. “It only helps us do our jobs better.”
MDOT uses the Bentley “OpenRoads” program to design projects from the ground up (surveying through construction), as well as using the software to create 3D models for projects that have already been designed in 2D.
“The 3D technology allows us to accurately design since it is actually designing a road based on a maximum of five-foot sections, as opposed to 50-foot sections like we did in 2D,” Geno said. “This allows for not only higher accuracy, but for finding issues that will need to be addressed during the design process as opposed to the construction process. This in turn saves money on the front end so that issues are less likely to pop up in the field during construction. When these models are used for construction in the field, it also helps keep people out of harm’s way because it helps remove stakes from a project since it is GPS based. This promotes a safe environment for MDOT surveyors and contractors.”
Currently, there are no projects in the MDOT construction phase that have been designed from the ground up in 3D. However, Geno said they have converted some 2D plans to 3D models. A few examples of this are the Lakeland Drive six-lane widening project, the Highway 98 and State Route 44 relocation in Marion County, and the State Route 501 bridge replacement in Scott County.
“Most contractors around the state use 3D models that were created using MDOT plans to generate a 3D model,” he said. “The Split Diamond Interchange in Madison County between Old Agency Road and Highway 463 on Interstate 55 are examples of projects generated in 3D using MDOT’s 2D model.”
Geno not only uses the technology himself, but teaches it to others. He recently conducted a class.
“I teach a three-and-a-half-day class two to three times per year to various design consultants and MDOT employees,” Geno said. “Most recently I taught the program to a group that included an employee who needed a refresher, an employee who had been here for 29 years but had never taken the class, and a new employee in his third week.”
A number of different types of professionals at MDOT benefit from learning how to use these programs. Geno said MDOT environmental staff benefit because it makes creating a model on a proposed alignment for environmental impact study very quick and easy. MDOT roadway designers benefit from using the software. And MDOT area engineers benefits since they will be evaluating models. Geno said MDOT field staff also benefit from it as it will be using these models in the field to build these projects.
As with any new technology development, it takes time and effort to learn how to efficiently use the programs. Geno said students studying civil engineering today are learning with these programs.
“It is completely different from 2D which, of course, presents a learning curve,” Geno said. “Engineers who have been designing in 2D are learning to change their design methods.”
The Alabama Department of Transportation used 3D CADD software to create a 3D virtual model of its $850 million I-10 Mobile River Bridge and Bayway Widening project proposed along Interstate 10. The 3D CADD program was used to help visualize projects to increase capacity for the existing bridge, reduce congestion, and provide a more direct route for transporting hazardous materials while minimizing effects to Mobile’s maritime industry.
Edwin Perry, project manager for the ALDOT 1-10 Mobile River Bridge project, said the 3D real-life, virtual visualization helped create stakeholder buy-in to construct a new six-lane, 215-foot vertical clearance bridge across Mobile River, and widen the current bridges across Mobile Bay from four to eight lanes. ALDOT used 3D CADD software to help people visualize how the expanded existing road and the proposed new bridge would fit in with the existing George C. Wallace Tunnel, the Battleship National Park and the skyline of Mobile.
“A lot of 3D renderings were used for the public hearings to give the public a better feel for the project and how it would fit in with the existing landscape,” Perry said. “There are a lot of issues with 1-10 in this area. Hopefully, by continuing with this project, we will be able to solve a lot of those.”
Currently, drivers have to slow down for a big curve before entering the Mobile Bay Tunnel headed east. The tunnel is only four lanes and has no shoulders.
“You can’t really widen a tunnel,” Perry said. “That is why we have to look at these various different alternatives.”
Perry said currently about once every three days, there is an accident in the heavily traveled corridor that causes traffic delays. The project is currently in the process of obtaining environmental permits with design work expected to begin in about a year. Perry said 3D CADD is getting more incorporated in their standard designs.
“More of our projects in the near future will be in 3D,” Perry said.