SR-158 Bridge Value Engineering: A Calibrated Effort-PPT Presentation

PPT Presentation

Pdf Summary

The SR-158 bridge project near the Alabama–Mississippi state line involved a 2,520-foot bridge with 21 bents. Its location in a protected MAWSS watershed made sediment control especially important. The conventional foundation plan required predrilling or jetting, with strict containment and disposal of water and spoils—adding substantial time and cost.<br /><br />As a value-engineering alternative, the team proposed 30-inch open-ended steel pipe piles (OEPs) for intermediate bents, instead of the specified 36-inch square concrete piles. The piles could be installed without jetting or predrilling, avoiding spoils. A project-specific testing plan included five static and five dynamic load tests; piles were vibrated to within 15 feet of their target tip elevations.<br /><br />Load tests showed that dynamic end-of-driving resistance was substantially below static resistance. Ratios of static to dynamic resistance ranged from 1.9 to 2.8, leading to calibrated factors of 1.5–2.0 for bearing graphs. The results were used to revise target resistance and guide field installation.<br /><br />At most tested bents, OEPs reached or exceeded the VE study’s estimated tip elevations. One notable exception was Bent 17, where an as-built tip elevation of 56 feet differed substantially from the 114-foot estimate.<br /><br />The alternative foundation approach was estimated to save about four months and $400,000—approximately 4% of the bridge cost—while reducing environmental impacts and giving the contractor greater control over testing.

Keywords

SR-158 bridge

Alabama-Mississippi state line

bridge foundation

open-ended steel pipe piles

value engineering

sediment control

load testing

dynamic resistance

bearing graphs

cost savings