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Traffic Barrier Guidelines Section 3.0 Potential Roadside Obstacles Hands-On Workshop III July 2013 1
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Potential Roadside Obstacles (cont.) Design Options: 1.Remove obstacle 2.Relocate obstacle 3.Reduce impact severity 4.Shield obstacle 5.Delineate obstacle 2
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Design Process – Begins at Concept Roadside safety MUST be part of the design process from the start. Examples of common issues: Embankment Side Slopes Drainage Structures Drainage Gutter Bridge Design BWA Scope/Work Load Reduced 3
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Potential Roadside Obstacles Gutters and Curbs Embankments Sign Supports Bridge Piers, Parapets, Abutments & Bridge Cones Noise Abatement Wall Drainage Structures Ditches Riprap Roadway Lighting ITS Systems Utility Poles Trees Bodies of Water Rock Cuts 4
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Type G-3 Gutters 5
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Type G-2 Gutters 6
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Gutters and Curbs ( Article 3.2) 7 Type “C” Curb Ramp Toll Plaza Only
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Gutters and Curbs ( Article 3.2) Gutter may be used with or without guardrail. Guardrail may be used with or without gutter. The need for each is determined independently. Do not use guardrail to shield improperly placed gutter. Guardrail used with gutter shall be at correct offset. 8
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Embankments (Article 3.3) Roadside Geometry and Terrain Features, Section 5.2.1 of the AASHTO Guide. 9
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Embankments (Cont) 10 Recoverable Foreslope – 1:4 (V:H) and flatter Non-Recoverable Foreslope – Between 1:3 (V:H) (inclusive) and 1:4 (V:H) (exclusive) Critical Foreslope – Steeper than 1:3 (V:H)
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Vehicle on Critical Foreslope
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Comparative Risk Warrants for Embankments (RDG Fig. 5-1b) 12
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Preferred Typical Section – Starting Point 13 Barn-roof foreslope using 1:6 allows easier: Placement of signs and light poles Transition to a bridge abutment & bridge cone.
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Sign Supports (Article 3.4) Overhead Sign Truss – Cantilever Type Overhead Sign Truss – Span Type 14
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Bridge (Article 3.5) Pier Abutment Cone Economical bridge designs usually result in the location of bridge piers, abutments, and parapets within mainline or ramp clear zones. Parapets 15
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Noise Abatement Wall (Article 3.6) Non-Crashworthy Noise Wall Crashworthy Noise Wall 16 Not preferred for new installations
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NAW Preferred Installations Place Wall Near ROW, Beyond Clear Zone 17
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NAW Preferred Installations When along roadway – install crashworthy NAW with snow storage (no guardrail for face of wall) 18
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Drainage Structure – Safety End Treatment Direction of Traffic Pipe Runners to match adjacent slope 19
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Drainage Structures (Article 3.7) Issues: Headwall not flush with embankment Pipe too short Headwall too close to roadway Steep slope just above headwall Skew 20
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Drainage Structures- Corrected 21
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Drainage Structure- Issues Issues-Culvert End Treatment Headwall & pipe runners too steep in embankment slope, non traversable Headwall not flush with embankment; obstruction 22
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Drainage Structure- Corrected 23
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Ditches (Article 3.8) Drainage Channels, Section 3.2.4 of the AASHTO Guide. 24
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Roadway Lighting (Article 3.10) 25
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Standard H1 – Grading Requirements 26
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Standard H1 – Grading Requirements 27
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Breakaway Light Pole Bases 28
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Roadway Lighting (Article 3.10) Controllers and Transformers 29
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Communication Systems and ITS Devices (Article 3.11) NID RWIS CCTV Camera Non-Breakaway 30
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Bodies of Water (Article 3.14) Bodies of water greater than 2’ in depth must be shielded. Locate detention basins well outside the clear zone. 31
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Questions? 32
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