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Recent AT Guideline Changes

Recent AT Guideline Changes. Existing Documents New Technical Documents Bridge Structure Design Criteria Bridge Design Bulletins Bridge Best Practice Guidelines Roadside Design Guide. Existing Documents. Hydrotechnical Design Guidelines Bridge Size Culvert Design Guidelines

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Recent AT Guideline Changes

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  1. Recent AT Guideline Changes • Existing Documents • New Technical Documents • Bridge Structure Design Criteria • Bridge Design Bulletins • Bridge Best Practice Guidelines • Roadside Design Guide

  2. Existing Documents • Hydrotechnical Design Guidelines • Bridge Size Culvert Design Guidelines • Culvert Sizing Considerations • BPG # 7 – Spread Footing

  3. New Technical Documents • Context of Floods in Alberta • Flood Envelope Curve Analysis • AT Open Channel Flow Equation • Alberta Rainfall Runoff Analysis

  4. Bridge Structure Design Criteria • Section 4e – Bridge Fills • No more CB6-2.3M22 • Headslope tool – elliptical fill transition • Bridge Fill Width = Gross Width + 2m • Fill taper rate – max. 30:1 • Section 4b – Min. Bridge Grade • Target minimum = 1% (drainage) • Every effort for 0.5% min. grade

  5. Bridge Design Bulletins • BD # 5 – Retaining Walls near Rivers • Issues : • Erosion - outflank/undermine • Failure – little warning, catastrophic • Repair – extensive, expensive • Inspection – specialized, systematic • Flexibility – accommodate future stages? • Recommendation : • Consider Other Options • Design – RPW, piling, structure mod.

  6. Bridge Best Practice Guidelines • BPG # 9 – Rock Protection • Typical details • Why preferred option • Bio – not at bridges

  7. Roadside Design Guide • Bridge Width (Section H5.4.1) : • Min. Bridge Clear Roadway = 9.0m • Match Road Design Clear Roadway • > 9000 AADT, shoulder = 3.0m • Max. shoulder width = 4.0m** • Urban – TAC shy distance (T3.1.6.4) ** Maximum for ring road structures is 3.5 m based on safety audit for AHD SW

  8. Roadside Design Guide Fig. H7.1 (Underpass Clearance)

  9. Roadside Design Guide • Section H9.2 – Pedestrian/Cyclist • Rural – shoulder OK • Systems Interchange – no pathway/sidewalks • Pathways ( TAC bidirectional multi-use min. ) – 4.2m wide on structure ( 3.0 plus shy dist. ) • WOL + Sidewalk (2.5m wide) typical on low speed/volume arterial bridges *** NOTE: warrants for supplemental urban planned facilities beyond basic in urban areas currently under review

  10. Future Guidelines/Clarifications • Vertical clearances – Pedestrian Structures • Parallel versus tapers on urban bridges • Use of retaining walls on high speed roadway bridges • Maximum/minimum grades/crossfalls on bridges • Combined effects of horizontal and vertical geometry on ramp bridges

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