Geotechnical Investigations. The proposed project is to remove the existing single-lane bridge crossing of ▇▇▇▇▇▇▇▇ Creek and replace it with a new bridge structure. The existing railroad flatcar bridge is 120-feet long and 13-feet wide. According to Caltrans bridge inspection reports, the existing foundations are spread footings at the abutments and steel H-piles at the piers and the structure is considered scour critical. Geologic mapping shows the site at the contact between Jurassic-Cretaceous Fransican Formation and Plio-Pleistocene Non-Marine sediments. The alluvial sediments are typically not associated with Naturally Occurring Asbestos (NOA) but this will be evaluated during the ISA. Bedrock is not exposed in the channel and bedrock may be deep below ground surface based on the surrounding terrain and geologic mapping. Bridge structure type has been tentatively defined in the RFP. It is indicated to be a reinforced concrete slab bridge in the range of 150±ft long and 22±ft wide supported on reinforced concrete wall-abutments. Suggested foundation types in the RFP include driven piles to 50-ft depths. CIDH piles may also be a feasible alternative for this site. Abutment locations and depth of pile caps will be established, in part, on the basis of projected channel grade and bank slope configuration/stability. It is assumed that abutments will be located at equal distances from the thread of the channel. Bridge line and grade are expected to generally match existing roadway. The existing roadway approaches appear to be on native ground (terrace materials) and it is understood that the roadway will be widened to accommodate wider travel lanes and shoulders.
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Geotechnical Investigations. The proposed project is to remove the existing single-lane bridge crossing of ▇▇▇▇▇▇▇▇ Creek and replace it with a new bridge structure. The existing railroad flatcar bridge is 120-feet long and 13-feet wide. According to Caltrans bridge inspection reports, the existing foundations are spread footings at the abutments and steel H-piles at the piers and the structure is considered scour critical. Geologic mapping shows the site at the contact between Jurassic-Cretaceous Fransican Formation and Plio-Pleistocene Non-Marine sediments. The alluvial sediments are typically not associated with Naturally Occurring Asbestos (NOA) but this will be evaluated during the ISA. Bedrock is not exposed in the channel and bedrock may be deep below ground surface based on the surrounding terrain and geologic mapping. Bridge structure type has been tentatively defined in the RFP. It is indicated to be a reinforced concrete slab bridge in the range of 150±ft long and 22±ft wide supported on reinforced concrete wall-abutments. Suggested foundation types in the RFP include driven piles or CIDH piles to 5060-ft depths. CIDH piles Depending on the consistency of the Plio-Pleistocene materials and the scour potential for the bridge, spread footings may also be a feasible viable alternative for this sitethe bridge. Abutment locations and depth of pile caps will be established, in part, on the basis of projected channel grade and bank slope configuration/stability. It is assumed that abutments will be located at equal distances from the thread of the channel. Bridge line and grade are expected to generally match existing roadway. The existing roadway approaches appear to be on native ground (terrace materials) and it is understood that the roadway will be widened to accommodate wider travel lanes and shoulders.
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