Session 3Grading Requirements for Guardrail End Treatments

Recoverable Slope 4:1 or Flatter

Traversable Slope3:1 to 4:1

Non-Traversable Critical Slope

Steeper than 3:1

Three Areas to Consider for Grading

Advanced Grading Adjacent Grading Run Out Grading

Per Bill Gulick

“You CANNOT Disconnect Grading and Guardrail”

Advanced grading 10:1 on Top of Pad

Side Slope 4:1 or Flatter

Advanced Grading if not properly done can cause a Rollover or

Vehicle may not hit End Treatment Properly

Adjacent Grading 10:1 on Top of Pad – 5’

WideSide Slope 4:1 Desirable 3:1

Max

Adjacent grading if not properly done can cause a

rollover

Run Out Grading 4:1 Desirable

3:1 Max

Run out grading if not properly done can cause a rollover or a collision with a fixed

object

KY Example - Good Grading, Guardrail Installed for Box

CulvertBut Pre Pass Box & Pole Only

95’

Grading Requirements Standard Drawing RBI-004

Installation of Guardrail End Treatment Type 1

2012 Std Draw shows 5’ of widening in the “Adjacent” area behind the guardrail

Grading Type 4A End Treatment

Grading Requirements Pads & SlopesGetting Good Pads but Poor Slopes beside

PadsGuardrail End Treatments Type 1 & 4A’s

2012 Std Draw shows 5’ of widening in the “Adjacent” area behind the guardrail – Sect A-A Side slopes 4:1 Desirable 3:1 Max

Minimum Length of Guardrail - including End Treatment – before a Fixed Object – 200

FeetTypical Guardrail Installations: Std Draw RBI-001, 002,Std Draw RBI-004 Type 1Std Draw RBI-005 Bridge ColumnStd Draw RBI-006 Sign Support

ALL CONTAIN THE FOLLOWING NOTE:

ALL CONTAIN THE FOLLOWING NOTE:Std Draw RBB-001 & 002Guardrail & Bridge End

Std Draw RBB-010 Guardrail Transition From Normal ShdTo Narrow Bridge

Q & A Time

1. What are the Names for the 3 Areas of Grading?

Advanced, Adjacent and Run Out

Q & A Time

2. Why do we need to grade an area in front of an End Treatment so Flat?

to ensure that a vehicle is stable at the

moment of impact and that its

suspension is neither extended nor

compressed

Q & A Time

3. Define:Recoverable SlopeTraversable SlopeCritical Slope

Recoverable Slope – 4:1 or Flatter Traversable Slope – 4:1 to 3:1 Critical Slope - Steeper than 3:1