That’s a Rebar Wrap

Autonomous Robots Helping Bridge Contractors Improve Productivity

Rebar-tying robot ties wires on bridge deck on Snake Run Bridge in Beaver County, Penn. Photos: Advanced Construction Robotics, Inc.

Autonomous rebar-tying robots are helping bridge contractors improve productivity by completing one of the industry’s most tedious and monotonous tasks – tying rebar on bridge decks.

The use of steel reinforcement bars to strengthen a concrete bridge deck is common practice that typically requires crews with specialized tools to hand tie wires around rebar intersections to stabilize the frames.

Fifteen months ago, TyBot, LLC, a wholly owned subsidiary of Pittsburgh, Penn.-based Advanced Construction Robotics, Inc., introduced TyBot, an electro-mechanical system that combines artificial intelligence and robotics to automatically tie rebar. According to Ty-Bot co-founders, Stephen Muck and Jeremy Searock, it is the first artificially intelligent (AI) robot in heavy civil construction.

Muck, still CEO and Chairman of Brayman Construction Corp, a  heavy contractor, talks about the need for a robot to tie rebar. He explains, “In the bridge world, tying rebar is a critical path activity that typically requires a crew to spike up to meet the desired schedule. It’s one of the least palatable jobs on a project, and studies show that productivity has dropped year-to-year. The robot is predictable and productive, doesn’t get hurt and works multiple shifts, day or night.”

Designed to attach to and run on the screed rails that contractors use for deck finishing, TyBot is an intelligent machine that combines sophisticated, tightly coupled algorithms, electronics and sensors set on a frame that spans the bridge deck.

Crews do not map the job beforehand—the entire task is autonomous. When deployed on a bridge with steel reinforcement bars, the robot will “see” an intersection and tie it. That said, Muck and Searock did include a wireless controller for monitoring that incorporates an override feature.

Installing TyBot system on Park Quarry Bridge in Beaver County, Penn.

“From day one in the design process, we put a lot of effort into making sure this is transparent to the industry,” says Searock. “You turn on the engine and the robot does the job. Technology-wise, it’s closer to a self-driving car than a conventional industrial robot in a factory.”

TyBot is designed to be used on bridges from 10 feet to 140 feet wide. It’s compatible with #8 by #8 rebar intersections and works to bridge design limits of 12% grade and 12% super-elevation and light enough that F-250 pulling a specialized aluminum trailer can haul up to 60 feet of the robotic system. The TyBot team estimates an effective production rate of 800 ties per hour.

TyBot was first used to tie rebar on the PennDOT Freedom Road bridge project in October 2017. Since then, it has been used to tie concrete deck slabs on the Snake Run and Park Quarry Road Bridges in Beaver County, Penn., and on bridge projects in New Hampshire, Virginia and Maryland. The TyBot team is gaining considerable momentum internationally as well. Look for the autonomous robot on bridges around the world in the coming years.