Cochran Mill Road Bridge over Tuscarora Creek

Transcription

1 Cochran Mill Road Bridge over Tuscarora Creek July 15, 2014 Brian Morrison, P.E. NOVA District Senior Structural Engineer (703)

2 Purpose & Need Purpose Update project status for permanent bridge on Cochran Mill Road Bridge over Tuscarora Creek. Existing Bridge Summary Bridge Condition New Bridge Design Criteria Plan and Typical Section The Way Ahead 2

3 Existing Bridge Summary The current structure is a 52-foot long steel beam timber deck superstructure supported on rubble masonry piers/abutments. Bridge was constructed in Bridge is currently classified as structurally deficient. Bridge is only capable of carrying about half of the current design live load. Superstructure is rated as poor due to severe steel deterioration. Following a 2012 inspection temporary repairs were completed in lieu of weight restrictions. Bridge hydraulic opening does not meet minimum 2-Year DEQ criteria.

4 Bridge Condition Significant rust scale with section loss & holes on beams ends with loss of support. Surface rust with isolated areas of section loss throughout beams. Bridge railing & approach guardrails do not meet current standards. Potholes, deteriorated patching, & depressed areas on wearing surface. Edge spalls below beams at pier. Voids & cracking in mortar at both abutment breastwalls. Scour holes below bridge.

5 Substructure Condition Have a condition rating of fair. Are constructed from rubble masonry (no reinforcing steel) and are of unknown capacity. Situated in a configuration that does not allow a replacement superstructure to meet minimum hydraulic opening criteria (requires longer bridge and raising profile). Are undermined and are scour prone. Typically, the above conditions render existing substructures unsuitable for reuse.

6 New Bridge Design Criteria The bridge section will carry two 12-0 lanes and 2-0 shoulders with a 17-6 wide shared-use path as recommended in the alternatives study report and is consistent with the County comprehensive plan ultimate configuration. The bridge opening will be sized to pass a 10-year flood level DEQ Criteria & satisfy FEMA floodplain criteria. Cochran Mill Road (ADT 1,600) will be open to traffic during construction and traffic will utilize a temporary one lane (reversible with signals) bridge. Incorporate aesthetic features for the approach retaining walls. Details will be coordinated with local stakeholders and finalized after a public hearing. Minimize Right-of-Way impacts.

7 Interim Roadway Plan

8 Roadway Plan

9 Construction Phasing

10 Construction Phasing

11 Interim Typical Section

12 The Way Ahead Preliminary design started in December 2012 with VDOT prescoping funds. Final design will begin late summer Public Hearing could occur in Winter 2015 and the project could be ready for advertisement in late Spring 2016 if construction is funded. Construction complete Summer Engineering costs: $500,000 (need additional funding) Right-of-Way and Utility costs: $40,000 Construction: $3,200,000 (currently unfunded) Total: $3,740,000 Ultimate 4-Lane Configuration Cost: $2,000,000 increase

13 QUESTIONS & COMMENTS Send comments via to: Brian Morrison, P.E. NOVA District Senior Structural Engineer (703)