Context-Sensitive Design for the Fulton Road Bridge Replacement
John C. Dietrick, PE, SE, and Jeff W. Broadwater, PE, Michael Baker Jr., Inc., Cleveland, OH
The Fulton Road Bridge in Cleveland OH, is a seventy-year-old concrete arch bridge. For many years this bridge has carried a significant volume of traffic 100' above the Cleveland MetroParks Zoo, Brookside Park, Big Creek, and two active railroad lines. Replacement of this concrete open-spandrel deck arch bridge has become imperative because of its severely deteriorated condition.
Because of its location over the Cleveland MetroParks Zoo, which is patronized by over a million visitors yearly, the bridge has long been a highly visible structure and an important community symbol. The bridge is one of few of its type and era still in use in Ohio. Great care has been taken to solicit and implement feedback from stakeholders and the public. A bridge alternative study has been performed to evaluate replacement bridge types, focusing on maintaining the unique character of the structure and minimizing negative impacts to the zoo, in the spirit of context sensitive-design.
After evaluating a number of conceptual bridge replacement types, three feasible alternatives were advanced for more detailed study and presented in a public forum. Based on preliminary engineering and public input, a precast concrete arch alternative, with six 210-foot spans to resemble the existing structure, was selected and advanced to final design.
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 railroads.
The conceptual design effort also encompassed a number of environmental, cultural and historic issues associated with replacement of the structure. The prominence of the structure, its location in a culturally significant neighborhood, and its visibility from afar provided incentive for a context-sensitive approach guided by an extensive bridge concept development and type study effort assisted by significant input from key stakeholders and public involvement.
The Fulton Road Bridge was constructed in 1932 and consists of six 210-foot concrete open-spandrel castin-place deck arch spans and concrete approach spans. The overall length of the bridge is approximately 1,600 feet. Four lines of arch ribs support the deck, which is a flat-slab integral with the spandrel columns. The structure carries four lanes of vehicular traffic over the Cleveland Metroparks Zoo, Big Creek, John Nagy Boulevard, and the Norfolk Southern and CSX railroad lines. 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.
Environmental, Cultural and Historic Issues
The existing Fulton Road Bridge possesses a number of unique characteristics that originate primarily from its appearance and location. The bridge crosses over the Cleveland Metroparks Zoo and is very visible from Brookside Park, Interstate I-71, and Pearl Road. The concrete cast-in-place deck arches give the bridge a unique appearance that is considered very desirable to maintain in this prominent site. Because of the significance of the existing structure and sensitivity of the site, considerable effort was put forth to identify environmental, cultural and historic issues that could impact the selection of replacement bridge types. Key issues included:
- Brookside Park Bridge under Fulton Road 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.
- Big Creek - Big Creek runs directly under the Fulton Road Bridge and flows nearly parallel to the alignment of the bridge near its center spans. The creek will affect access to portions of the bridge during construction and will affect the means available to the contractor for construction and demolition.
- Railroad Coordination - The Fulton Road Bridge crosses over two sets of tracks near the north end of the bridge, operated by CSX and Norfolk Southern. Measures will need to be taken during construction to ensure that negative impact to the operation of the railroads is minimized.
- Zoo Operations - Portions of the bridge are in close proximity to animal enclosures and zoo facilities; pedestrian trails are located directly under two spans of the bridge. Noise, vibration and reduced air quality from demolition and construction, as well as limitations on access to portions of the zoo during construction, have potential for negative impact on zoo operations.
The issues described above helped to establish some overall geometric constraints for the new replacement bridge and provide the basis for the context of the bridge site. These general parameters included the overall form of the bridge, span lengths, pier locations, and vertical clearance limitations. Specifically, the following geometric parameters were decided upon at the outset of the preliminary design after careful consideration of the key issues described above.
- Because of 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.
- Because of the appeal of the existing structure's appearance, it was decided that a dramatic change in span lengths from the existing 210' spans would not be desirable. More importantly, to limit the impact to the zoo and Brookside Park as described above, and to minimize right-of-way acquisition, it was deemed important to maintain piers at the existing pier locations.
- The presence of 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 supporting arch ribs for deck arch structures.
These geometric parameters, established early in the conceptual design, provided a context for the development of bridge replacement alternatives and put practical limitations on feasible replacement types. By establishing these parameters early, determination of
the preferred bridge replacement type was facilitated by eliminating some clearly inappropriate structure types from the beginning, and negatively or positively affecting the evaluation of others. This early focus was consistent with the context-sensitive approach established for the project and helped lay the foundation for the context-sensitive solutions developed in the preliminary design phase.
Development of appropriate concepts for replacement of the Fulton Road Bridge was carried out in a systematic process: 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, narrowed the options to a final preferred alternative. 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.
Technical Advisory Committee
A critical component of the design team's approach to the concept development was the formation of a Technical Advisory Committee (TAC) to supervise the development and evaluation of bridge replacement concepts. The TAC was comprised of key technical staff from the major stakeholders involved in the project, including Cuyahoga County (OH) Engineer's Office, City of Cleveland, Ohio Department of Transportation, Cleveland Metroparks Zoo and the Federal Highway Administration.
This group was comprised of those individuals who best understood the context of the bridge and could best promote a true context-sensitive solution for the new structure. The main functions this group provided included:
- Liaison between the design team and important stakeholders with significant interest in the project;
- Direction on the development of evaluation criteria used to assess
concepts, as well as comparative weighting of evaluation criteria;
- Technical assistance with evaluation of alternatives against
- Assistance with communicating decisions and potential alternatives to the public.
Determination of Feasible Alternatives
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 reasons of visibility and cultural significance, global
aesthetics was a very important criterion for evaluating the bridge
- 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 were 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 zoo and 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.
- 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.
At this stage, the design team and the TAC cooperatively rated the preliminary concepts on a scale from one to ten on each of the evaluation criteria. These ratings resulted from extensive discussion among the TAC members from which a consensus was achieved on both the ratings and the weighting of the importance factors for each criterion. Each criterion was assigned a weight factor in relation to its perceived relative importance. An overall score for each preliminary alternative was then calculated based on the sum of the ratings multiplied by the weighting factor. In this manner, the three feasible alternatives were identified:
Feasible Alternative A - Precast (Contemporary) Concrete Arch - This alternative is a precast concrete arch bridge with 210-foot 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-foot 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.
Public Involvement Process and Selection of Preferred Alternative
Public input on selection of a preferred alternative followed identification of the three feasible alternatives. The design team worked carefully to make sure that all feasible alternatives shown to the public were constructible and could be funded with available resources. No options were communicated to the public unless the alternative could meet these key criteria.
Input on a variety of issues associated with the project was obtained from key technical stakeholders and 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, 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.
With a preferred alternative identified, final design has proceeded with the same focus on providing context-sensitive solutions to the replacement of this bridge. The primary goal of the context-sensitive approach at this stage is to identify final design elements and construction methods that will satisfy commitments made to stakeholders in the conceptual design phase and to minimize negative impact. The primary focus of the preliminary design that is currently ongoing consists 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. The end arch elements will be temporarily supported using stay cables attached to the pier columns; crown segments will be erected as drop-in elements and post-tensioned to the end segments.
- Further aesthetic enhancement. The public outreach effort and use of a context-sensitive approach to enhance the aesthetics of this highly visible structure have not yet concluded with the selection of a preferred alternative. The design team continues to solicit public input on focused elements of the bridge where aesthetic enhancement has been deemed to be appropriate. These elements include bridge barriers, fencing, structure lighting and feature lighting. This continued effort to solicit public input has helped maintain support and enthusiasm and has enhanced the context-sensitive nature of the project.
- Structural design elements. The final structural design has also 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 is ongoing and will be completed by the end of 2005. The new Fulton Road Bridge is scheduled to be open to the public by the end of 2008.
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