Worth The Challenge

July 24, 2006

The time has come to implement the studies and provide congestion relief to southwest Fort Worth, Texas. The SH 121T (Southwest Parkway) Project has been in the planning stages for more than 40 years by the city of Fort Worth, the Texas Department of Transportation (TxDOT) and the North Texas Tollway Authority (NTTA). Southwest Parkway is needed to provide congestion relief in southwest Fort Worth and to provide better access into downtown from Johnson County.

The time has come to implement the studies and provide congestion relief to southwest Fort Worth, Texas. The SH 121T (Southwest Parkway) Project has been in the planning stages for more than 40 years by the city of Fort Worth, the Texas Department of Transportation (TxDOT) and the North Texas Tollway Authority (NTTA). Southwest Parkway is needed to provide congestion relief in southwest Fort Worth and to provide better access into downtown from Johnson County. The 15-mile roadway, extending from downtown Fort Worth to FM 1187 in southwest Fort Worth, will consist of a six-lane controlled-access highway from IH 30 to Altamesa Blvd., and a four-lane controlled-access highway from Altamesa Blvd. to FM 1187.

The 9-mile segment from IH 30 to Altamesa will be designed by NTTA and the segment to FM 1187 will be a TxDOT Fort Worth project. The NTTA section of Southwest Parkway project is the subject of this article.

Stakeholders in this corridor include the cities of Fort Worth and Benbrook, Tarrant County, TxDOT, FEMA, Corps of Engineers, Union Pacific Railroad, organized local groups, and several local homeowners associations. The two main challenges of this project were to bring all the stakeholders to agreement and to find funding for the $825 million project. The NTTA, working with the local agencies and stakeholders, has accomplished both tasks.

The NTTA, a political subdivision of the state of Texas, was created under Chapter 366 of the Transportation Code to acquire, construct, maintain, repair and operate turnpike projects for the four counties around Dallas and Fort Worth. The four counties, consisting of Tarrant, Denton, Collin and Dallas Counties, compromise the board members who, along with a board member appointed by the governor, guide and direct the operations of NTTA.

Management of the $825 million Southwest Parkway Project was handled by NTTA using their standard management tools. Mark Bouma, P.E., the NTTA Director of Engineering, and Ghaleb Sunna, P.E., NTTA Director of Design, developed the program management process for NTTA. First, NTTA selected a general engineering consultant (GEC), who then assisted in selecting section engineers. This 9-mile Southwest Parkway project was divided into five sections, each with numerous challenges unique to each section that required innovative solutions.

Sectioned off

The major challenge of Section I is raising IH 30 approximately 20 ft while maintaining through-traffic. This is further complicated by the need to reconstruct all ramps to provide local access from the new roadway, while preserving local access.

Section II crossed the Clear Fork of the Trinity River twice and impacted nature trails along the river corridor. There also are several residential subdivisions adjacent to the corridor which required close coordination during plan development.

The Union Pacific Centennial Yard crossing requires placing bents between active tracks in Section IIB, which minimized the options for bent placement. The development of a clear-zone map for the dozen or so tracks that will be crossed identified potential bent locations which influenced the bridge type selection. Construction sequencing and beam placing activities require close coordination with UPRR, which set the allowable contractor working schedule which had to be incorporated into the design concept. In addition, the crossing of Hulen Road over the rail yard and the new Southwest Parkway requires unique construction staging planning for the street improvements.

Southwest Parkway crosses two freeways (IH 20 and SH 183), and requires the design of 10 direct-connect ramps, six braided ramps, 13 slip ramps and five pairs of overpass bridges. In Section III, existing SH 183 will be lowered about 25 ft to accommodate the new Southwest Parkway crossing, which requires an extensive staged construction plan in order to maintain local access and preserve freeway through-traffic. An existing city embankment stockpile is located within the right-of-way. This will need to be moved across both highways and trucked to the north to the other segments to balance project earthwork.

The most southern section, Section IV, requires a design to improve an adjacent low-water crossing at the Fort Worth and Western Railroad crossing of Altamesa Blvd., which is adjacent to the east right-of-way line of Southwest Parkway. Construction sequencing must preserve local access to the adjacent Oakmont Hospital District and impacts the proposed diamond intersections along the corridor.

The NTTA consultant selection process focused on the unique requirements of each section. Section I and III required section engineers with recent TxDOT interchange experience. Section II and IV required section engineers with freeway, controlled-access and Fort Worth municipal street design experience. Section IIB required a section engineer with extensive UPRR coordination and crossing design experience. By matching project requirements with section engineer experience, NTTA was able to focus the consultant selection process on the best-qualified team for each section.

In addition to standard freeway design components, NTTA developed context-sensitive aesthetic details for the project. These details were a significant contribution to the consensus building process with all the stakeholders. Unique features of the details included planter areas, landscaped medians, project-specific wall fascia treatment, a combination of concrete U-beams and prestressed concrete beams on each overpass bridge span and project-specific column details. In addition, pedestrian and bicycle traffic facilities were incorporated into the project to accommodate alternative modes of travel.

NTTA advertised a request for proposal on July 7, 2005, for section-design engineers. Proposals were submitted on Aug. 16 and interviews were held in October 2005. The short-listed consultants focused their presentations on the sections for which they felt they were uniquely qualified and identified issues and solutions during their respective interviews.

Although cost savings was a key element for NTTA, consultants also focused on the unique experience and resources their respective teams bring to the agency. HDR Engineering focused their presentation on leveraging multiple office resources and through teaming partners to design a $220 million interchange in the required 18 months. HDR used their previous design approach on the FM 1604-SH 281 five-level interchange for the San Antonio District of TxDOT as an example of a successful expedited design schedule. Design consultants for all five sections were selected, contracts negotiated and notice-to-proceed was given on Jan. 30, 2006. HDR Engineering was selected to be the section engineer for Section III, the IH 20/SH 183 five-level interchange.

12 months in a project

From the consultant's perspective, the HDR project manager decided the plan to solve the project issues with an expedited schedule was as important during the consultant selection process as it will be during design. HDR Engineering assembled their design team based on their understanding of not only the project requirements, but also the NTTA objectives. Understanding that the design of a five-level interchange in 18 months that crossed two freeways would be a significant challenge, HDR used the FM 1604/SH 281 design approach as an example of a proven project approach.

The FM 1604/SH 281 project had a compressed 12-month design schedule. Based on the schedule and design constraints, HDR Engineering utilized the resources of several HDR offices and subconsultant partners.

The roadway components of FM 1604 were designed by HDR and the roadway components of SH 281 were designed by a separate team member. The multiple bridges were separated by similar types and assigned to multiple bridge design teams. By identifying unique design segments that could be independently advanced through project development with minimal coordination points, HDR was able to meet the 12-month design schedule. This concept was proposed to NTTA during the consultant selection process with the added point that the same structural design teams that just completed the FM 1604/SH 281 interchange were available to start work on Southwest Parkway. This recent experience in expediting major freeway interchange design was an important component in consultant selection.

The large number of Southwest Parkway bridges dictated the use of four separate HDR bridge groups and two bridge subconsultants as well as four specialty subconsultants. HDR studied all 32 bridges and assigned bridges of similar types to each structural design team. This enabled each team to develop a common set of bent, abutment and slab designs and use those details for all of their assigned bridges. In addition, one design team was tasked with design of common structural elements that would be used by all structural teams. This will result in standardized details for all bridge elements which will facilitate the contractor’s ability to standardize forms. This should translate into an economical design in both design costs and construction costs.

With respect to the roadway design, HDR assigned the Southwest Parkway design segment to their Dallas roadway group and the SH 183 segment to the San Antonio roadway group. Using this approach, each design group could advance their plans independently of each other, requiring only minimal coordination interface points.

Money from everywhere

This $825 million project is too large for funding to come from one agency. Therefore, the major financing element will be tolling. NTTA will operate and maintain the facility after completion. In addition to tolling, several stakeholders also are providing funding for the project. For example, TxDOT will fund the two interchanges at IH 30 and IH 20/SH 183, and the city of Fort Worth will acquire right-of-way and adjust utilities. This unique partnership of several agencies was the key element in advancing the project to the design stage.

Through the use of creative financing, multi-agency participation, extensive public involvement, unique aesthetic concepts and a section-specific consultant selection process, NTTA has taken a major step towards improving mobility in Fort Worth. After decades of studies, Southwest Parkway is advancing from a planning concept to a much-needed transportation project.

About The Author: Sunna is director of design for the North Texas Tollway Authority. Ruth is project manager for HDR Engineering.

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