page_title: High Five Interchange
section_title: History
hierarchical_section_title: High Five Interchange / History
context_page_description: The High Five Interchange is one of the first five-level stack interchanges built in Dallas, Texas. Located at the junction of the Lyndon B. Johnson Freeway and the Central Expressway, it replaces an antiquated partial cloverleaf interchange constructed in the 1960s.
  The $261 million project was started in 2002 and completed in December 2005. It was designed by the HNTB Corporation and built by Zachry Construction Corporation.
  The interchange is considered by Popular Mechanics to be one of "The World's 18 Strangest Roadways" because of its height, its 43 permanent bridges and other unusual design and construction features.
  In 2006, the American Public Works Association named the High Five Interchange as "Public Works Projects of the Year".
context_section_description: The High Five Interchange project was planned as a replacement for the existing, antiquated interchange that accommodated 500,000 vehicles daily and was located in one of the most intensely developed commercial zones in Dallas. It was a collaborative project between the TxDOT, affected motorists and property owners, and the primary contractor, Zachry Construction. An essential consideration was to complete the project with as little disruption to the traffic flow as possible.
  Reasons for upgrading the interchange, in addition to the need to increase traffic flow and reduce congestion, were to improve air quality, safety, and local access.
  Zachry Construction Corporation submitted the lowest bid and was awarded the $261 million contract by TxDOT, the largest ever by that agency. The construction contract for the High Five Interchange was unique in that it contained elements not found in other construction project contracts. For example, it specified the concrete maturity method to be used to ensure the concrete's strength (the first time TxDOT had ever done so), and contained an early completion bonus, a sliding scale of up to $11 million if the company completed the contract within four years.  Also built into the construction contract was a provision that Zachry was charged for "lane rentals" by TxDOT for time they closed down traffic lanes—fees based on hourly assessments and the time of day the lane was closed. The fees ranged from $50 to a high of $110,000 for rush hours. In order not to interfere with traffic flow during construction, the new interchange was designed largely as elevated flyover ramps and viaducts so they could be built high over the existing junction lanes; once traffic was transferred to the new structures the old lanes could simply be closed off and removed. Little of the original interchange remained when the project was finished.
  To save time and money, innovative construction methods were employed: The original plans called for the segments of the long ramps and spans (used to direct-connect roads) to be made of steel, but because building with steel would interfere with heavy traffic flow during construction, cast-in-place segmental concrete was substituted in the plans. However, Zachry decided to use precast concrete segmental bridges, rather than casting the bridge elements in place, and used a unique machine, designed and constructed by Deal S.R.L. of Italy and costing about $1 million, to move the pieces into place.
  During the construction, 2.2 million cubic yards of earthwork was used, 350,000 cubic yards of concrete was mixed on site, and 300,000 square feet of retaining walls were built. Additionally,  40,000 feet of drilled shafts  and 75,000 linear feet of drainage pipe were completed. In addition to the construction of 43 permanent bridges, six temporary bridges were built, resulting in 2.3 million square feet of bridge deck.
  The project was designed by the HNTB Corporation who provided professional engineering consultation throughout the construction, which had begun in 2002 and was completed in December 2005, more than 13 months sooner than planned.
caption: High Five Interchange under construction in 2005
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