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ST0301-CS040415FEEESE- NICHOLS MEMORANDUM TO: FROM: SUBJECT: DATE: CC: Suzan Taylor Melinda Polley Bethel Road and Grapevine Creek Bridge Options April 15, 2004 Chris Moomaan; Tricia Hatley The Bethel Road bridge that crosses over Grapevine Creek is scheduled to be replaced. The existing two-lane bridge is approximately 28 feet wide and 188 feet long. The bridge has three spans with two sets of piers carrying the middle span. The bridge consists of concrete beams supported by the concrete piers and concrete bridge abutments. The proposed bridge will be 43.5 feet wide with room for sidewalks on both sides of the roadway. FNI was asked to investigate and develop several options for the bridge reconstruction. Four options will be presented in narrative format. The narrative will include a brief description, advantages and disadvantages, a conceptual cost estimate and an estimate of time required for construction. Lastly, a summary matrix is provided as a single page reference. The four options that will be presented are 1) close road during construction, 2) remove bridge and reconstruct 1/2 at a time, 3) build a temporary crossing and 4) realign the roadway. Option 1 - Close Road This option would require that the road be closed during the duration of the bridge construction phase. Access would be allowed up to the bridge; however all traffic would need to be detoured during construction. Advantages · No concern with traffic conflicts · Open/accessible work area · Shorter time of construction · Less cost for construction · Ability to use standard bridge beams · Able to eliminate piers currently in creek C:\Documents and Settings/staylor\Local Settings\Temp',Bridge Options doc FREESE AND NICHOLS ~ 4055 INTERNATIONAL PLAZA, SUITE 200 ! FORT WORTH, TEXAS 76109-4895 TELEPHONE: 817-735-7300 ! METRO: 817-429-1900 ! FAX: 817-735-7491 Bridge Alternatives April 15, 2004 Page 2 of 5 Disadvantages · Disruption of traffic · Need to try to attempt major construction elements during summer school vacation · All traffic will need to be detoured · Detoured traffic will potentially impact other roads (residential) · Public safety routes could be impacted · Disruption to school bus routes Discussion - This bridge currently has three spans across the creek. The precast concrete members used in the middle span are not "standard" TxDOT beams, meaning they are not readily available. If the entire bridge is demolished prior to the start of construction, a TxDOT standard beam can be used that will eliminate the need for the piers in the creek. This will allow the bridge construction with a single span. In order to do this the beam will be deeper (greater distance from top to bottom of the beam). Traffic will need to be rerouted during the construction process. The traffic will either have to be rerouted along Sandy Lake to the north or Southwestern Blvd. to the south. Public safety access routes as well as school bus routes would also need to be reevaluated. Construction of the bridge could be accomplished with relative ease because the contractor could work unimpeded with no interference with continual traffic. The fact that a bridge could be built with piers into the creek also provides for a benefit since there is less chance of pier scour from the creek and there would be less encumbrance to storm water flows in the creek. Option 2 - Construct 1/2 at a time This option would remove enough of the bridge to allow for one lane of traffic and to construct 1/2 of the new bridge. Once this portion the bridge was constructed, the other portion would be removed and the construction of the remaining half would take place Advantages · Allows limited travel · Allows public safety access Disadvantages · Possible structural instability of the bridge · Conflicts of the existing bridge components with the new bridge · Piers would need to be left in place · Safety concerns regarding edge protection during construction · Limited work space due to traffic and in-place bridge components Bridge Alternatives April 15, 2004 Page 3 of 5 · More comprehensive traffic control would be required · Bridge would need to be larger than necessary Discussion - This process would require that a portion of the existing bridge be demolished and a portion of the new bridge be constructed, while leaving enough of the existing bridge to allow for one lane of traffic. In order to provide for one lane of traffic less than half the bridge could be demolished during the first phase. A travel lane plus sufficient space to place traffic barriers along the edge for safety considerations would need to be provided. The demolition could only consist of the bridge deck and longitudinal beams. The piers and pier bents would need to stay in place in order to carry the remaining traffic lane. The pier bents were not designed as cantilever sections therefore can not be removed. There would be significant construction conflicts between the new bridge and the remaining bridge components. A single span bridge could not be constructed since the depth of the longitudinal beams would conflict with the remaining piers and pier bents. Additional traffic control would need to be put in place to insure adequate safety. There would be two primary options: 1) allow only one way traffic (either east or west) during the entire construction or 2) install temporary traffic signals which would allow alternating traffic flows on a set timer. Option one would be a more consistent alternative. If drivers know that hey can only go one direction at all times they will adjust their routes for their opposite direction trip. Option two would cause significant delays since traffic would be stopped in each direction for a set period of time. This control could be supplemented by flagmen during the day, but at night would only be controlled by the temporary traffic signals. The work area would be restricted and costs would increase based on this factor. Option 3 - Temporary Creek Crossing This option would construct a temporary crossing adjacent to the existing bridge. Advantages · Traffic will be maintained · Public Safety access will be maintained · Construction can be accomplished with minimal interference Disadvantages · Cost of building 2 bridges · Additional ROW would be required · Exiting lift station and sewer line might be in conflict with temporary structure · Need to build temporary road for temporary bridge · Potential environmental issues Discussion - This option would require the construction of a temporary creek crossing, demolition Bridge Alternatives April 15, 2O04 Page 4 of 5 of the existing bridge, construction of the new bridge and demolition of the temporary crossing. Due to the depth of the charmel section and the potentiaI stormwater flows a box culvert would be impractical. A new bridge, designed to all the same parameters as a permanent bridge would need to be constructed. Additional ROW would need to be obtained. The crossing would probably need to be constructed to the north of the existing bridge due to constraints to the south. A new road would have to be constructed to be used only for the temporary crossing. Once the temporary facility is completed the existing bridge can be demolished. Construction of the new permanent bridge could proceed with little interference. There is a lift station and sewer line that might be in conflict with a temporary facility. These would need to be permanently relocated. The major issue with this option is the time and expense of constructing t~vo bridges. Option 4 - Realign Roadway This option would be similar to Option 3 with the exception that the "temporary" bridge would become the permanent bridge. Advantages · Traffic will be maintained · Public Safety access will be maintained · Construction will take place with a minimum of interference · Single span bridge can be constructed · Piers within the creek will be eliminated Disadvantages · Requirement for additional ROW · Roadway alignment · Required relocation of lift station and sewer line Discussion All the elements of Option 3 would apply here with the exception that only one bridge would be constructed. There is some concern with the realignment of the new roadway. Due to the proximity of Denton Tap Road to the east there would need to be a reverse curve from the bridge approach to Denton Tap Road. Provided there is enough space this should not be a major issue and could actually be used as a traffic calming feature in this area.