Partnering to Preserve a Historic Piece of Miami
The Hanover Skew Bridge was built in 1952 as a way to transport the increasing automobile traffic to and from Miami International Airport from the east, specifically Miami Beach and booming downtown Miami.
In the early 1950s, Miami politicians were closely monitoring municipal spending and chose this affordable bridge design to reduce costs and improve traffic flow. The bridge was necessary to accommodate both vehicular and increasing boat traffic on the Miami Canal. While this structure was constructed, traffic was detoured upstream for 16 months, as reported in news articles from the 1950s.
This structure replaced the antiquated lift bridge built in the 1920s. The engineering firm of Hardesty & Hanover developed the Hanover Skew bridge design, which provided 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.
In the 1970s, 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. The traffic jams caused vehicles to back up onto SR 112 from the off ramp to NW 36th St., causing 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. They 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 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 design 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 us. We 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's commitment to FDOT to maintain traffic during the demolishing and construction phases.
When construction started, the machinery was partially submerged in its original location inside the pier. MCM’s Senior Project Manager Ana DePriest recognized that a portion of this historic bridge needed to be preserved. She contacted the principal and staff at Miami-Dade County Public Schools (M-DCPS), and GT Baker Aviation Technical College Principal Rene Mantilla and Air Frame Instructor Alan Munoz, who have partnered with MCM in the past.
Ana requested that the Airframe Program at GT Baker assist with restoration of the gear. 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 Mario Saavedra, a student and owner of Bull’s Eye Sandblasting. Saavedra volunteered his time resources and expertise. In addition, M&M Steel provided tools, materials and welding assistance to the students. With a collaborative effort between industry and students, the gear was restored.
Recognizing the historic nature of the bridge and its components, the FDOT and MCM project staff approached Gus Pego to request presentation of this motor gear to the department as a historic art piece. Pego agreed to display the motor gear at the entrance to the Miami FDOT District 6 Headquarters, and FDOT maintenance staff prepared a display pedestal for the gear.
The historic importance of the gear demonstrates mechanical significance and engineering ingenuity of the 1950s. The collaboration between the Florida Department of Transportation, GT Baker Technical College and MCM reflects the importance of partnerships between industry and education.
The dedication was made on February 25, 2015 as part of the National Engineers Week celebration at FDOT D-6.