3D design and construction analysis

Proposed highway design model shown in its real-world environment. Image: courtesy of Bentley Systems

BIM workflows help Alabama Department of Transportation maintain schedule on I-59/I-20 reconstruction.

The Alabama Department of Transportation (ALDOT) initiated an estimated $750 million reconstruction project to replace structurally deficient and functionally obsolete interstate bridges through downtown Birmingham. The existing bridges are located along the only east-west interstate through the Birmingham Business District, which is primarily an elevated six-lane-divided highway through this 3.5-mile section of the city. The twin bridges include 189 bridge spans that require new girders and deck sections. The reconstruction project consisted of 23 new bridges, eight bridge widenings, five bridge replacements, and 16 retaining walls.

ALDOT understood that the construction process had to be precise and efficient with as few construction delays as possible. For these reasons, ALDOT used 3D design and construction analysis to identify potential issues and potential construction delays before the project broke ground. The visualization group of ALDOT’s design bureau was tasked with providing a complete 3D model. To support precise cost estimation and lower bids for the project, it was critical that the digital engineering model include accurate and timely data to support multiple uses, including visualizations, design checks, construction analysis, clash detection, right-of-way negotiations, lawsuits, aesthetics, and construction bidding.

The project faced many challenges, including a fast-paced schedule, information coordination, utility coordination, public involvement, and changes in the overall design. Because of public and stakeholder concerns, the visualization group used MicroStation Luxology rendering capabilities and LumenRT to create visualizations that were instrumental in winning approval for the project.

To meet the objectives of replacing the structurally deficient and functionally obsolete interstate bridges, ALDOT used 3D design technology to ensure efficient designs, and eliminate costly construction delays. Scheduling of the project was critical, and the design needed to be created quickly and information exchanged across teams to support the 14-month construction schedule.

A critical element in any construction project are utilities, and ALDOT invested millions into locating and relocating them, engaging the visualization group to ensure that there were no clashes in the model. The organization used MicroStation’s clash detection capability to ensure that utilities were properly located in the design to minimize errors in construction. ALDOT saved more than $10 million by implementing the BIM review methodology supported by Bentley’s technology.

Bentley’s applications also allowed ALDOT to reduce the environmental impact by minimizing noise levels in a developed urban area and eliminating dangerous and unnecessary access points along the interstate. OpenRoads was used to create the digital terrain models, and StormCAD, CulvertMaster, and FlowMaster were used to address drainage and utilities design. ALDOT used ProjectWise to allow designers, department heads, drafters, reviewers, and consulting teams to have access and ensured that everyone was working on the right data.

Using ProjectWise on the project, which is currently under construction, helped the consulting firms save thousands of dollars on time and delivery, and ALDOT to save tens of thousands of hours creating 3D models to meet the rigorous scheduling demands. ProjectWise enabled inspectors and contractors to access design files on tablets, saving hundreds of hours in meeting time and processes used on previous workflows.

“Using Bentley’s integrated civil design and collaboration applications allowed us to quickly produce an accurate 3D model that included grade, terrain, signage, pave, striping, signals, lighting, bridges, drainage, and utilities, said Matt Taylor, P.E., state engineer, ALDOT. “It eliminated design errors, minimized construction change orders, and helped save waste in public money while building safer infrastructure.”

Information provided by Bentley Systems (www.bentley.com).