When MCM started the reconstruction of the 63-year-old skewed bascule bridge, the machinery was partially submerged inside the machinery room.
“We knew as soon as the outside wall of the bascule pit was cut, the water would become a problem,” said MCM’s Senior Project Manager, Ana DePriest. “We took great precautions to sheet pile the exiting roadway to maintain three travel lanes, while still removing the existing structure on both sides.” The historic importance of the gear demonstrates mechanical significance and the engineering ingenuity of the 1950s. Preservation of the gear included major sandblasting, welding to repair the base and a final restorative paint coat.
The collaboration between the Florida Department of Transportation, George T. Baker Avitation School and MCM reflects the importance of partnerships between industry and education.
Partnering to Preserve History
The Hanover Skew Bridge was built in 1952 and was built as a way to transport the increasing automobile traffic to and from Miami International Airport from the east, specifically Miami Beach and the booming downtown Miami.
In the early 1950’s, Miami politicians were closely monitoring municipal spending and chose this affordable bridge design which would reduce costs and improve traffic flow. The bridge was necessary to accommodate both vehicular and increasing boat traffic on the Miami Canal. This structure replaced the antiquated lift bridge which was built in the 1920’s. The engineering firm of Hardesty & Hanover developed the Hanover Skew bridge design. This design would provide a solution to the skewed crossing of the Miami Canal at NW 36th Street. The design scheme would efficiently use only one lift and one bascule leaf mounted on a single lift pier. This bridge design is one of only three constructed in Florida and one of four constructed in the United States; all were built between 1945 and 1963. Hanover Skew bridges are unique because of the angled Tail Girders. While this structure was constructed, traffic was detoured up stream for 16 months, as reported in news articles from the 1950’s.
In the 1970’s the Miami Canal was closed to navigation at NW 36th Street and therefore the bascule leaf was placed out of operation. In 2010, the Florida Department of Transportation, D-6 (FDOT) recognized that this 65 year old bridge needed replacing due to the insurmountable number of repairs required to the steel grate leaf, other maintenance issues and traffic concerns as well as increasing capacity within this corridor. As you are aware of the traffic jams caused vehicles to back up onto SR 112 from the off ramp to NW 36th St. causes many delays on SR-112.
PROCUREMENT PROCESS TO REPLACE THE BRIDGE
The Department of Transportation was designing the replacement of the Hanover Skew using its internal forces. The Department encountered many challenges 
during the final stages in developing the traffic control plans in order to allow the bridge to remain open during the demolition and construction of the new bridge. The original concept proposed by FDOT resulted in an extensive maintenance of traffic detour plans that would adversely affect the traveling public, business and inroads to Miami International Airport. FDOT originally estimated the project to take 500 days with full closure of NW 36th St at the canal for a minimum of 200 days. Knowing the advantages of a “Design Build” process, DOT opened the project to other contractor and engineering firms. In an attempt to utilize the industry’s innovative ideas and to overcome some of the design and construction challenges of the project, a decision was made by Gus Pego, FDOT District 6 Secretary to advertise the project as “Design Build”. This allowed for MCM (contractor) and APCTE (lead designer) to provided innovation with significant cost and time savings implementation as compared to the traditional design-bid-build delivery method.
In July 2013, the Design Build Team of MCM and APCTE, both Miami firms, submitted a successful technical and price proposal to remove and replace the skewed bascule bridge. In January 2014 construction began on the new structure. The winning team proposed to remove and replace the bascule with twin single span fixed bridges while maintaining traffic across the canal. Accomplishing this task required phased demolition of the old bridge concurrent with the construction of both new bridges; consequently, reducing the construction time by 120 days and the closure of the bridge to zero (0) days.
CHALLENGES AND OPPORTUNITIES
Inside the bascule bridge the floor of the counterweight pit was elevation -15 feet. The existing machinery was on the mezzanine platform at elevation – 1 foot inside the bascule pier. The Miami Canal mean water elevation is + 2.5 feet. Removing the existing bascule pit and shoring the counterweight inside with the below canal elevation took ingenuity from both the Designs and the Project Construction Staff. MCM knew that as soon as the outside wall of the bascule pit was cut, the water would be upon them. MCM took great precautions to sheet pile the exiting roadway to maintain three travel lanes while still removing the existing structure on both sides. This was part of MCM commitment to FDOT to maintain traffic during the demolishing and construction phases.
When the construction started, the machinery was partially submerged in its original location inside the pier. MCM’s Sr. Project Manager, Ana DePriest, recognized that a portion of this historical bridge needed to be preserved. She contacted the principal and staff at Miami-Dade County Public Schools (M-DCPS) GT Baker Aviation Technical College; Principal, Rene Mantilla and Alan Munoz (Air Frame Instructor), who have partnered with MCM in the past. Ana DePriest requested that the Airframe Program at GT Baker to assist with restoration of the gear. The restored piece would be on permanent display at the Florida Department of Transportation’s District Office in Miami. The request was accepted and GT Baker students and staff volunteered their time and resources. The preservation work included, major sandblasting and welding to repair the base as well as a final restorative painting. The sandblasting was performed by a student, Mario Saavedra who owned his own sandblasting company – Bull’s Eye Sandblasting. Mr. Saavedra volunteered his time resources and expertise. In addition, M&M Steel also provided tools, materials and welding assistance to the students. With a collaborative effort between industry and students, the gear was restored.
The FDOT Project Staff and MCM Project staff realizing the historical nature of the bridge and the components approached Gus Pego to see if this motor gear can be presented to the Department as Historical Art Piece. Mr. Pego agreed to display the historical motor gear at the entrance to the Miami FDOT District 6 Headquarters. The historical importance of the gear demonstrates mechanical significance and engineering ingenuity of the 1950’s. FDOT Maintenance staff prepared the display pedestal for the gear.
The creative willingness to work together between Florida Department of Transportation, MCM and GT Baker Technical College reflect the importance of collaboration and partnerships between industry and education.
This dedication was made on February 25, 2015 as part of Engineers Week of Celebration at FDOT D-6.
For more information on the gear and the reconstruction of the Hanover Skew Bridge, please contact Carolina Norgaard at cnorgaard@mcm-us.com or (305) 541-0000. Visit http://www.mcm-us.com for more details.
