Saving Time in St. Clair County, Michigan With Press-Brake-Formed Steel Tub Girders

Project Overview

In 2017, the St. Clair County Road Commission (SCRC) chose to replace two 70-year-old severely deteriorated steel superstructures with a new press-brake-formed steel bridge superstructure. These existing bridges carry the Marine City Highway, which is the main thoroughfare into and out of Marine City, Michigan for commercial and school traffic. The highway is a two-lane road that handles more than 10,000 vehicles per day. The two bridges included a 25-foot-span steel beam bridge (Structure 4-08) and a 35-foot-span steel beam bridge (Structure 4-09) on a 45-degree skew. 

Originally built in the early 1950s, the steel beam bridges were designed for H-15 loading and had reached the end of their long 60-year-service lives. The existing beams for both bridges consisted of hot-rolled W18 wide flange sections, 18 inches deep. The entire bridge cross-section depth, including concrete deck and overlays, totaled 2'-4.5".

The traffic detour route for each bridge closure included seven miles of gravel roads and more than 15 minutes out of the way for drivers, so SCRC considered options to expedite the schedule for a full-closure construction project. To reduce the duration of the construction closure and reduce costs, it was imperative to utilize and rehabilitate the existing abutments, requiring the new superstructure to match the existing superstructure's weight and depth. SCRC also wanted to maintain constructability by county maintenance crews. The best option for SCRC was the press-brake-formed steel tub girder bridge system, which allowed the team to meet all of these goals.

Methods of Construction 

The existing abutments were reused and rehabilitated, eliminating costly and time-consuming substructure demolition and replacement work in the water. This was made possible by the light weight of the press-brake-formed steel girder superstructure, which provided no additional dead load pressure on the spread footing abutments. Special steel tub girders were fabricated to match the depth of the existing superstructure so that no modifications were needed for the existing abutment bearing elevations. This also reduced the roadway approach pavement replacement limits and saved costs.

Fabrication of the Bridge System 

The Con-Struct™ Press-Brake-Formed Steel Prefabricated Bridge System was chosen for its light weight, adjustable depth, low cost, integral backwalls and ease of construction. Con-Struct™ consists of a precast concrete deck on galvanized, press-brake-formed steel tub girders. The superstructure was prefabricated by ADL Systems in Portland, Michigan, which provided a quality, cost-effective final product. The Con-Struct™ Prefabricated Bridge System was designed for the required HL-93 (MOD) Michigan Department of Transportation (MDOT) live load and met all applicable MDOT and AASHTO design criteria. The 8-inch-thick precast concrete deck was overlaid with a thin epoxy overlay which provided the final driving surface and additional protection from deicing salts. The galvanized steel tub girders were designed to be 18 inches deep, providing a total superstructure thickness of 2'-4", which closely matched the depth of the removed superstructure. The Con-Struct™ superstructure was manufactured with integral backwalls so there was no need to cast substructure concrete in the field, further expediting the installation schedule.

Shipping and Erection 

Both superstructures were transported to the construction site in six individual units. The 25-foot-span units of Structure 4-08 weighed approximately 10 tons and required only a county-owned excavator for erection. The 35-foot-span units of Structure 4-09 weighed 15 tons, so the county chose to rent a 150-ton crane to set them. For Structure 4-08, the superstructure units arrived at the job site before 8:00 a.m. and were all set in place by the county before 11:30 a.m. The crane for Structure 4-09 arrived at roughly 9:00 a.m. and was ready to lift the bridge units within an hour. Delivery of the superstructure units was timed to coincide with the readiness of the crane. By 1:00 p.m., the six units for Structure 4-09 had all been set in place.


The six individual units were then tied together with a concrete closure pour. The SCRC maintenance crew cast a 6-inch-wide High Performance Concrete deck joint, creating a continuous 41’-6”-wide concrete bridge deck. Transpo Industries T-17 Methacrylate Polymer Concrete was used in the deck joint. The deck joint width and rebar lap length were specifically designed for the T-17 material based on rebar development length testing provided by Transpo Industries. 

The deck for Structure 4-08 was overlaid with a thin epoxy overlay to further protect the concrete driving surface. Due to weather limitations, the thin epoxy overlay on Structure 4-09 will be placed in Spring 2018 under temporary lane closures.

Final Product 

Over the next three days, the roadway approaches were paved with asphalt, and the drainage ditches in all four quadrants were regraded and seeded. Guardrail was installed on the bridge deck utilizing anchor bolt holes that were precast into the Con-Struct™ bridge deck fascia units. The St. Clair County Road Commission was able to successfully replace these two deteriorated bridges in just over a week by using innovative prefabricated structural elements. With the use of the Con-Struct™ Prefabricated Bridge System, this project provided a new structure with a service life of over 60 years that is sustainable, cost-effective, aesthetically pleasing and environmentally friendly.

Structure 4-08

Structure 4-09

Marine City Highway Bridge Replacement Project Team

St. Clair County Road Commission

William Hazelton
Director of Engineering
Tel: 810.388.4030

Willbanks Metals 

Gabriel Castillo
General Manager
Tel: 918.836.2929

ADL Systems, Inc.  
Ryan Vroman
Project Manager
Tel: 517.647.7543

TEG Engineering, LLC

Guy C. Nelson, P.E., S.E.
Structural Engineer 
Tel: 616.261.8630