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-P 1 ' Bridge Structuml Design Services The existing bridge also has no abutments. The end spans are cantilevered from the piers with no substantial end support which has resulted in approach pavement maintenance problems. (Photo 13) Surface runoff on the bridge deck currently drains directly off into the river through the metal barrier rail on the south side. On the north side it flows along the sidewalk curb until it gets to the end of the bridge where it further aggravates the problem at the joint between the bridge and the approach pavement. The bridge deck is cracked and in need of sealant or perhaps a concrete overlay. There are two hinges in the superstructure which also have had ongoing maintenance problems due to failing joint protection anchorage. If we widen the bridge as proposed, we would need to match the existing structure type, span arrangement, hinge locations, and cantilevered end conditions in order to simulate the same deflection characteristics of the superstructure and all of these problems will be perpetuated. In order to stage the removal and widening construction while maintaining two lanes of traffic, the new superstructure would have to be constructed in 3 portions. (See stage construction, Figure 1) We could improve upon the photo 13. The approach hinge joints and add a small pavement is failing due seat abutment at each end in to a lack of abutment. order to reduce maintenance problems in these areas but the buried end span problem would still exist. Also, since the new piers would need to align with the existing piers, there would be conflicts with the existing foundations and piling that would need to be addressed during construction. None of these problems are insurmountable but the cost of the widening will be high due to the inefficient span layout, severe limitations on the contractor's work space, and many maintenance items that would need to be addressed along with the widening construction. Additionally, when all is done, there would still be a portion of this bridge that will be 50 years old. Another option would be to replace the entire bridge in two stages with a'completely different structure type and configuration See Figure 6. The replacement bridge could be substantially shorter, eliminating the buried end spans by locating the abutments just outside of the channel lining limits. The hinges could be eliminated altogether with a bridge of this length. The individual span lengths could easily be doubled reducing the number of piers in the river which in turn would reduce the construction activity in the river and shorten the construction duration. By re -spacing the piers, conflicts with existing foundations could also be eliminated. 04601 324.5557 DMJM HARRIS I AECOM The construction duration would be further reduced since a total replacement could be built in two portions rather than three for the widening option. Further reduction in construction duration could be realized by using precast girders which would also eliminate falsework in the river. Proper abutments with short approach slabs and joint seals could be constructed instead of the cantilevered end spans so that future maintenance of the approach pavement is minimized. An additional benefit of the shorter bridge is that the realignment of access roads from First Street will not be required. This will also reduce the length of the retaining wall required in the northeast quadrant as it will no longer wrap around the access road and extend northerly to support the road. The end result would be a brand new bridge with an anticipated useful life of over 75 years and minimal required maintenance. And the best part is, the total replacement cost would likely be less than the cost to construct the widening. The square foot cost to construct a bridge widening is typically higher than that of new construction. That will be the case in this instance as well, especially with the staging required for the construction while salvaging an 18 -foot wide segment. As currently proposed, the bridge widening would be 39,400 square feet. The replacement bridge would be 34,740 square feet, almost 5,900 square feet less (see Figure 6). DMJM Harris estimates that with this reduction in square feet, coupled with the lower cost of new bridge construction, might net the city significant savings for the bridge construction segment of work. The HBRR Guidelines provides for the possibility of replacing a bridge in the following instances if it the SR is greater than 50 (HBRR Section 6.2.2): 1) The bridge is functionally obsolete. This is the case with this project as First Street has six lanes of traffic in either side of the bridge, resulting in the bridge being a chokepoint with only four lanes. 2) The most cost effective solution is a replacement. If a detailed cost estimate determines that the replacement is more cost effective, along with no other impacts such as environmental, then the Caltrans local assistance liaison can approve the replacement. DMJM Harris is willing to champion the City's cause and open discussions with Caltrans, both here in District 12 as well as Structures Local Assistance in Sacramento, where we have an established relationship. With the substantial increase in construction costs over the past couple of years, the potential reduction in the bridge costs with the replacement option is worth exploring to bring the total project costs back down, providing a direct savings to the City's matching funds for the project.