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ROADSIDE SAFETY &

GUARDRAIL DESIGN

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PRESENTATION

ROADSIDE SAFETYClear Zone & Obstruction Free ZoneTreatment of Obstructions Construction CZ

GUARDRAIL DESIGNGR PlacementGR Design for 3R ProjectsGR at Large Structures

Design Exceptions Common Mistakes & OmissionsPractice Pointers

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Clear Zone Concept

Space for Vehicles Run-off-the-Road to Gain ControlAmount of Obstruction-Free Area for Vehicle RecoveryLike “Airport Runway” - Free of ObstructionsPlace Roadside Hazards Away from Pavement

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Clear Zone Applicability

New Construction & Reconstruction3R/Partial 4R on InterstatesDesirable for 3RCost Effectiveness of Corrective MeasuresClear Zone values are not absoluteCZ Outside R/W – Use R/WEngineering Judgment Provide Consistent CZLevel 2 Design Exception

5Figure 49-2A

Clear Zone Distances

Total ADT on 2-Lane RdwysDirectional ADT on Divided Highways.Compare CZ for Aux. Lane vs MainlineShow CZ on Typicals

6Figure 49-2C

Horizontal Curve Adjustments

CZ = K * CZtc cz

K = Fig. 49-2BCZ

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Obstruction Free Zone Concept

3R ProjectsAmount of Obstruction-Free Area next to RdwyNot the same as CZ Provide CZ, if practicalOFZ Width Varies

Des Speed, Arterial/ Collector, ADT Provide Traversable DitchesLevel 2 Design Exception

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Typical Obstructions

TreesRevetment Riprap Ditches Non-Traversable Culvert EndsNon-Traversable DitchesConcrete HeadwallsUtility poles Bodies of water, permanent water depth>2’

Non traversable castings

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1) Remove or Redesign2) Relocate Outside of CZ3) Make Breakaway to Reduce Impact Severity4) Shield with Traffic Barrier5) Delineate if other Treatments not Practical

Treatment of Obstructions

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Construction Roadside Safety

IDM 82-4.0 Traffic Control Roadside Safety Reduce Motorist’s Exposure to Potential HazardsMaximize SeparationMinimize Positive Protection Devices

Applies to all Project TypesAnalysis & Review required for each MOT Phase

Construction CZFig. 82-4B

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Construction Roadside Safety

Temporary Traffic BarrierFlare Ends Outside of Const. CZAvoid Openings in BarriersAvoid using in Tapers. Provide Shy Line OffsetCheck Horizontal SSD thru Tapers/Transitions

Plan DetailsShow CZ on Typical MOT SectionsShow CZ Design SpeedAllowable Flare & Taper RatesSummarize Quantities for each Phase

Pavement Drop-offsPrefer to Close Lane3” Max Drop-off at End of DayTemp Wedge at 1:1 next to Lane

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GR Lateral PlacementPlace as Far Away from EP as PossibleShy Line Offset - Fig 49-5F Evaluate Alternatives

Additional CostReduced Barrier length, MaintenanceAccident History

INDOT Std Revisions Under Review8’ posts Backfill Material - Cohesive soils not CAB

Pave Shldr to Face of GR if offset 2’ or lessIf GR offset > 2’, Addt’l 2’ Paved not req’d

Varies

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GR at Curb Locations

Avoid using GR behind curbs Best to use Mountable CurbOffset GR to Shy Line OffsetGR at Face of Curb

Shy Line Offset

E.P

.

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Barrier Deflection

Clearance Face of GR to Fixed ObjectBased on Dynamic Deflection of Barrier/GR INDOT Std Revisions 8’ posts & BackfillCheck for Fixed Objects and Drop-offs

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GR Need Horizontal Curves

GRAPHICAL SOLUTION REQUIREDINVESTIGATE BOTH ALTERNATIVESUSE SHORTEST LENGTH OF NEED

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GR Alternate Offset

Tapered GR Example

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Non-Recoverable Slopes

Non-Recoverable Fill Slope

No Obstructions in Non-Recoverable Slope

Point of Hazard*

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GR Design Non-Recoverable Slopes

Traversable Ditch Cross Section Preferred

Example GR Design with 3:1 Slopes

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GR Design Non Recoverable Slopes

Example GR Design with 3:1 Slopes

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GR at Large Structures

New Construction 70 MPH Des SpeedNew Alignment – Divided HwyPerpetuate CZ thru Structure

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Drainage Structures

1’ to 5’ Cross PipesUse Safety Metal ESSkew > 10 Deg Use GBES

5.5’ and Larger – End Inside CZIf Cost Effective, provide Traversable ESDesirable Place GR at 12’ from EPUse Nested GR if Low Fill

5.5’ and Larger – End Outside CZDesirable Place GR on slope away from EP Desirable Place GR at 12’ from EP

Ditch InletsE-7 and F-7 Not Within CZ Use Pipe Catch BasinOther Type with less than 4” Protrusion

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Level 2 DECZ and OFZProvide Brief RationaleAlternates Considered

Document to FileSubmit to Project ManagerDiscuss at Field Check Local Projects need LPA Sign-off

Design Exceptions

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Incorrect CZ DistanceIncorrect CZ AdjustmentCZ Not Shown on Typical SectionsObstructions within OFZ or CZObstructions not Shielded or TraversableNon-Traversable DitchesDesign Exceptions Not Documented Using less than 100’ of Nested GR

Common Mistakes & Omissions

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Perform CZ reviewPlot CZ/OFZ on Plans Provide Consistent CZDetermine if any obstructions within CZDetermine/Verify Corrective ActionDiscuss CZ/OFZ at Field ChecksDocument DeficienciesCheck MOT Plan and CZ

Practice Pointers

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ROADSIDE SAFETY &

GUARDRAIL DESIGN