Section 5 Palmetto SR826/836 Interchange (Bridges 9, 11, 15, and 19) – Miami, Florida
The reconstruction of Section 5 Palmetto SR 826/836 Interchange will create safer and less congested travel for 430,000 vehicles traveling through the interchange daily.
This $559 million design-build-finance project involves the construction of an Interchange between SR 826 and SR 836, two limited access facilities, as well as the reconstruction of SR 826 at Flagler Street and SR 836 at NW 72nd Avenue interchanges. Capacity improvements include the reconstruction and widening along both SR 826 and SR 836, and the construction of 46 bridges. The project will provide new direct connector ramps for major improvements and collector-distributor ramps to eliminate existing geometric and operational deficiencies.
Four high-level precast segmental bridges traverse the core of the inter-change and form the centerpiece of the intersection. These bridges are 46 feet wide and range in length from 31,100 feet to 2,450 feet. Total deck area is 360,718 square feet, with 7,764 linear feet for the segmental bridges. The longest span is 266 feet, the tallest pier is 81 feet and there are 783 total segments.
The curved segmental bridge ramps are the third level of the interchange with radii down to 590 feet and a proposed maximum superstructure deck height of 95 feet above ground. All of the bridges are supported on 24 inch pile foundations and reinforced concrete piers and caps.
Innovation of Design and/or Construction
Design innovations reduced construction costs by nearly $100 million dollars. The redesign reintroduced three points of access to the Expressway that would have been lost in the original design plan, a much-preferred option for the Florida Department of Transportation (FDOT) and the area’s traveling public. Three out of four Alternative Technical Concepts (ATCs) were accepted for segmental bridges:
- FIRST USE OF DIABOLOS IN THE STATE. FDOT allowed diabolos for the first time based on the advanced design and demonstration of their successful application on segmental bridges in other states. Traditional bent steel pipes were eliminated, segment weight was reduced allowing for variable tendon geometry and continuous external tension ducts. External tendons will reduce future maintenance costs through improved future access for tendon replacement, as well as upgrading and stressing of any single strand inside the box.
- HAUNCHED SEGMENTS. Increased in span lengths reduced the amount of temporary supports adjacent to the highway and simplified the design of the interchange. Expansion joints were eliminated. This also increased the efficiency of post-tensioning and provided the capacity to support the launching gantry.
- POLYSTYRENE HOLLOW PIER COLUMNS. Use of Polystyrene in the hollow pier columns cores (except for solid bases and caps) eliminated the need for interior formwork, thereby reducing the amount of concrete material and overall mass of the structure.
- PIER CAPS. The pier caps were designed to support the balanced cantilever during construction, and include loop tendons through the caps to tie down the launching gantry and curved balanced cantilever superstructure. In addition to their vital functional role in the construction process, the pier caps contribute to the overall aesthetics, an important factor considering the prominent location of the interchange.
- NON-TRADITIONAL SHAPED PIERS. Using non-traditional shaped piers, adjusting the footing size to accommodate conditions, and increasing span lengths all helped improve maintenance of traffic sequencing, which was critical to accelerating the project schedule. Advance planning for building the foundation, for what would be the last segmental bridge, much earlier in the schedule was another critical aspect.
The design-build team realized that the critical path depended on speed of construction of the high-level segmental bridges. Most notable and significant among these design solutions was the decision to build the four segmental bridges “from the top down.”
- Use of a 460-ft. self-launching overhead gantry to build the precast segmental bridges in balanced cantilever over the core of the interchange reduced the need for temporary supports on the ground and segments that were stabilized off the pier caps.
- The casting yard was located 8 miles away from the project and transportation time of the segments ranged from 30 to 90 minutes.
- Three casting machines were utilized, one for pier and expansion segments, and two for typical segments. There were no rejected segments.
- Equipment and construction had to move fast and Quality Control was a key to keeping the project on the critical path. The engineer of record for the high-level segmental bridges understood these challenges and built the design into the construction methodology.
Aesthetics/Harmony with Environment
The bridge design, which included haunched segments, met a major project goal – strong aesthetic requirements. The segmental bridge design is highly-aesthetic and features mechanically stabilized earth (MSE) walls. Multi-color, Energy Star LED lighting that are mercury-free, long-lasting and economical will be added to the four high level segmental bridges to enhance the stunning architectural details at night.
- $332.67 per square foot.
- Segmental bridge costs: $120 million.
Total deck area: 360,718 sq. ft.
Minimization of Construction Impact
The design offered unique challenges integrating underlying roadways, canals and Maintenance of Traffic (MOT) requirements into the layout of these segmental bridge ramps. Nightly road closures were implemented to allow for erection of segments (11PM – 5AM).
This project was constructed in the Miami International Airport flight path and had FAA Requirements. The high level segmental flyovers are built over multiple roads that carry 430,000 vehicles per day and are the tightest elevation curves erected in the United States. The all overhead erection method eliminated the need for falsework and cranes, as well as 5 MOT phases that would have impacted traffic, while providing a safer work environment.
Great solution in a difficult urban environment. Proportioning piers caps to accept temporary jacks for cantilever stability during construction was an innovative way of eliminating temporary stability towers, reducing impacts to the motoring public. Rapid construction completed 4½ years ahead along with significant cost savings proves once again, segmental is a competitive structure type. First use of diabolos in Florida was proven successful.
Florida Department of Transportation
BCC Engineering, Inc.
Community Asphalt Corporation,
Condotte America, Inc.,
the De Moya Group, Inc., JV, LLP
Contractor Engineering Services:
Finley Engineering Group, Inc.
Construction Engineer and Segmental Bridge Design:
Finley Engineering Group, Inc.
Construction Engineering Inspection:
AIM Engineering and Survey, Inc. and Eisman & Russo, Inc.
Constructability Review/Estimating Services:
Formwork for Precast Segments:
VStructural, LLC (VSL)
The D.S. Brown Company
The D.S. Brown Company
Sika Corporation and Pilgrim
The Euclid Chemical Company
Rizzani de Eccher
Overhead Gantry and Casting Machines:
Casting and Erecting Segments:
Rizzani De Eccher
2015 ASBI Award of Excellence