A Zoo Keeper

March 1, 2006

The Fulton Road Bridge in Cleveland, Ohio, is a 70-year-old concrete arch bridge that for many years has carried a significant volume of traffic 100 ft above the Cleveland MetroParks Zoo, Brookside Park, Big Creek and two active railroad lines. Replacement of this concrete open-spandrel-deck arch bridge, which was constructed in 1932, has become imperative because of its severely deteriorated condition.

The Fulton Road Bridge in Cleveland, Ohio, is a 70-year-old concrete arch bridge that for many years has carried a significant volume of traffic 100 ft above the Cleveland MetroParks Zoo, Brookside Park, Big Creek and two active railroad lines. Replacement of this concrete open-spandrel-deck arch bridge, which was constructed in 1932, has become imperative because of its severely deteriorated condition.

Because of its location inside the Cleveland MetroParks Zoo, which is patronized by over a million visitors yearly, the bridge has long been a highly visible and important symbol to the community. The bridge also is one of the few of its type and era still in use in Ohio. Great care has therefore been taken to solicit and implement feedback from stakeholders to fully appreciate and understand the context of the bridge site. A bridge alternative study has been performed to evaluate replacement bridge types, focusing on maintaining the unique character and significance of the structure and minimizing negative impacts to the zoo, in the spirit of context-sensitive design.

Based on preliminary engineering and public input, a precast concrete arch alternative, with six 210-ft spans to resemble the existing structure, has been selected and advanced to final design, which is currently ongoing. Final design has continued the context-sensitive approach by attempting to incorporate design solutions and construction methods that best address the unique context of the bridge and its site. Parabolic arch rib segments will be fabricated in 65-ft, 70-ton pieces and erected using temporary towers and stays supported on the pier columns. This proposed top-down approach to the arch construction will minimize the negative impact to the zoo and the railroads.

Remaking history

The conceptual design effort encompassed a number of environmental, cultural and historic issues associated with the prominence of the structure and its unique context.

The Fulton Road Bridge consists of six 210-ft concrete open-spandrel cast-in-place deck arch spans and concrete approach spans. The overall length of the bridge is approximately 1,600 ft. Four lines of arch ribs support the deck, which is a flat-slab that is integral with the spandrel columns. The structure carries four lanes of vehicular traffic over the Cleveland Metroparks Zoo, Big Creek, John Nagy Boulevard, the Norfolk Southern and CSX railroad lines, and Brookside Park Bridge. The Brookside Park Bridge is a three-hinged concrete arch which was constructed in 1909 and currently carries pedestrian traffic in the Zoo directly under the Fulton Road Bridge. This structure is on the Ohio Historic Bridge Inventory and must be protected during removal of the existing bridge and construction of the new bridge.

As a result of the structure’s age and long-term exposure to deicing chemicals, significant deterioration has occurred, including moderate to severe spalling of concrete and exposure and corrosion of reinforcing steel. Cantilevered sidewalks were removed from the structure many years ago, and in 2004 the four lanes of traffic on the structure were reduced to two lanes. Because of the extensive nature of the deterioration in the structure, rehabilitation of the structure was not judged to be a practical alternative.

The existing Fulton Road Bridge possesses a number of unique characteristics that originate primarily from its appearance and its location. The bridge crosses over the Cleveland Metroparks Zoo and is very visible from Brookside Park, I-71 and Pearl Road. The concrete cast-in-place deck arches comprising the structure give the bridge a unique appearance that is considered very desirable to maintain in this prominent site.

General geometric parameters which provide the basis for the context of the bridge site include the overall form of the bridge, the span lengths, pier locations and vertical clearance limitations. Specifically, the following geometric parameters were decided upon early in the preliminary design.

  • Because of the strong sentiment and personal attachment to the existing arch bridge, it was decided prior to the development of alternatives that the new bridge would be “arch-like” in appearance;
  • Similarly, because of the appeal of the existing structure’s appearance, it was agreed that a dramatic change in span lengths from the existing 210-ft spans would not be desirable. More importantly, to limit the impact to the zoo and Brookside Park and to minimize right-of-way acquisition, it was deemed important to maintain piers at the existing locations; and
  • The two railroads at the north end of the structure introduced vertical clearance requirements that affected the permissible structure depth at this location. Since the bridge is very high over the valley, this would not prevent the use of normal structure depths for typical structures, however it does have an impact on the geometry of deck arch structures.
These geometric parameters provided a context for the development of bridge replacement alternatives and put practical limitations on feasible replacement types. By establishing these parameters early, the determination of the preferred bridge replacement type was facilitated by eliminating some clearly inappropriate structure types.

TACful approach

The development of appropriate concepts for the replacement of the Fulton Road Bridge was carried out in a systematic process whereby the design team started with a wide range of possible structures, and in a step-by-step fashion, with the guidance of a Technical Advisory Committee (TAC), narrowed the options to a final preferred alternative. The process of eliminating concepts and determining a final preferred alternative was performed by measuring alternatives against a well-defined set of evaluation criteria, which were weighted on the basis of perceived importance and impact on the overall success of the project.

A critical component of the design team’s approach to the concept development was the formation of a TAC to supervise the development and evaluation of bridge replacement concepts. The TAC group was comprised of key technical staff from the major stakeholders who best understood the context of the bridge, including the Cuyahoga County, Ohio, engineer’s office, city of Cleveland, Ohio Department of Transportation, Cleveland Metroparks Zoo and the Federal Highway Administration. The TAC has been instrumental in reaching consensus from the multiple stakeholders and keeping the project on schedule.

Based on analysis of preliminary alternatives, the design team determined three feasible alternatives which best met a series of objective criteria. This was accomplished by evaluating and ranking each preliminary concept according to the following key criteria:

  • Aesthetics—For the reasons of visibility and cultural significance, global aesthetics was a very important criterion for evaluating the bridge concepts;
  • Stakeholder preference—This criterion is a measure of the reaction of stakeholders to the appearance of the structure and of the extent to which the public could be expected to accept and embrace the bridge;
  • Initial cost—This criterion is an evaluation of the estimated initial cost of construction for each alternative. Initial cost estimates were approximate and based on approximate structural quantities that had been determined from preliminary engineering analysis;
  • Construction impact—This criterion evaluated the extent to which construction would result in significant temporary or permanent impact on the surroundings, including the Metroparks Zoo and the railroad lines;
  • Constructability—Each alternative was evaluated on the basis of the ease of construction, the extent to which complexity and the potential for delays or problems in construction were minimized and the extent to which the alternative would maximize the use of local labor and materials; and
  • Future maintenance and life-cycle costs—Future life-cycle costs refer to expenses that recur over the life of the structure that are necessary to maintain the functionality, serviceability and safety of the structure. On the basis of this evaluation, three feasible alternatives were identified:
Feasible Alternative A—Precast (Contemporary) Concrete Arch: This alternative is a precast concrete arch bridge with 210-ft arch spans similar to the existing structure. This alternative employed the use of modern materials and construction methods with four spandrel columns in each span, giving it a more contemporary appearance than the existing bridge.

Feasible Alternative B—Precast (Traditional) Concrete Arch: This alternative is intended to match the appearance of the existing bridge. A cast-in-place concrete arch similar to the existing bridge evaluated very positively on the strength of its aesthetics and stakeholder preference. Recognizing the impact that the formwork required for a cast-in-place solution would have on the park and zoo, this alternative attempted to recreate the appearance of the existing bridge with precast elements.

Feasible Alternative C—Concrete Delta Frame: The third feasible alternative was a precast concrete delta frame bridge with 210-ft spans. This alternative represents a more significant visual departure from the existing bridge. The delta frame was made to appear more arch-like by increasing the curvature of the supporting legs at the piers.

Input from the public on the selection of a preferred alternative followed the identification of the three feasible alternatives. An important element in successfully achieving a preferred alternative is that the design team worked carefully to make sure that all of the feasible alternatives shown to the public were constructible and could be funded with available resources.

Input on a variety of issues associated with the project was obtained from key community stakeholders at various stages of the concept development. This input was a critical element in arriving at a true context-sensitive solution. After defining the feasible alternatives a public meeting was held and the public was asked to select a preferred alternative. After receiving all public input, the Contemporary Concrete Arch alternative was selected as the preferred alternative.

Final thoughts

With the identification of a preferred alternative achieved, final design proceeded with the same focus on providing context-sensitive solutions to the replacement of this bridge. The primary goal of the context-sensitive approach was to identify final design elements and construction methods that will satisfy the commitments made to the stakeholders in the conceptual design phase and to minimize negative impact. The primary focus of the preliminary design consisted of the following:

  • Defining a construction scheme with precast concrete elements that will minimize negative impact to the site. The current design scheme uses three precast arch segments for each arch span, which will be prefabricated and shipped to the site. Where possible, arch elements will be temporarily supported on shoring towers during construction. Where the use of shoring towers is not feasible, arch elements will be temporarily supported by stay cables supported from pier columns;
  • Further aesthetic enhancement. The public outreach effort and the use of a context-sensitive approach to enhance the aesthetics has focused on bridge barriers, fencing, structure lighting and feature lighting. Continued efforts to solicit public input have helped maintain support and enthusiasm and have enhanced the context-sensitive nature of the project; and
  • Structural design elements. The final structural design also has focused on other elements important to a comprehensive context-sensitive approach, such as initial cost and life-cycle costs. For example, the new bridge will be designed to have no intermediate expansion joints between the two abutments. In addition, a vertical curve has been introduced into the final bridge profile such that the drainage can be accommodated at the ends of the bridge only, with no intermediate downspouts or scuppers.
Final design of the preferred alternative was ongoing and completed in March. The new Fulton Road Bridge is scheduled to be open to the public by the end of 2008.

About The Author: Dietrick and Broadwater are with Michael Baker Jr. Inc., Cleveland.

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