FHWA ProVAL Software IRI Smoothness Acceptance Analysis

Diamond Grinding Simulation

Brian L. Schleppi

ODOT Office of Technical Services

Proposal Note 555 Workshop

January 28, 2014

Overview

• Using ProVAL to determine compliance with PN 555

• How to model the geometry of any given diamond grinding machine

• Using the Smoothness Assurance Module (SAM) in ProVAL to develop Corrective Action Plans (live ProVAL demonstration)

• Questions

High Speed and Lightweight Inertial Profilers

International Roughness Index (IRI) Using profiles to simulate vehicle response

(What the public “feels”)

50 mph

IRI Sensitivity

1.0

2.0

1 2 5 10 2 5 100 2

Duration (ft)

0

.5

1.5

Sensitivity Wheel Hop Body Bounce

ProVAL Demo

Using ProVAL 3.40

to evaluate overall

and localized roughness

Grinder Setup

Head Position = Lf / Wheel Base

Grinder Setup

Grinder Setup

Head Position

– If head is centered half way between effective wheelbase then direction of grinding doesn’t matter so much

– If head is not centered, then direction

becomes increasing important as the position is skewed toward one end or the other

Grinder Setup

Head Depth

– If all wheels and the grinding head are sitting on the same plane, then the grinding head would be at “zero” depth, negative head depths are below that plane, and positive head depths are above the plane

– A minor change in head depth (as small as 0.05”) has a

major effect on depth of material taken and IRI reduction: rear wheels of machine ride on the ground surface

How Grinders vs. Simulation work

Grinders – Operate in 3-D

– Abrasively remove material

– Geometry & Dimensions dictate what can be fixed

– Machine Frame is a moving reference

Simulation – Operates in 2-D

– Constant head depth

– Oblivious to speed of machine and “riding out of the cut”

18-foot Grinder

18-foot Grinder Setup

“Bump” Grinder

“Bump” Grinder Setup Front Bogies Fully Retracted

“Bump” Grinder Setup Front Bogies Fully Extended

20-foot Grinder

20-foot Grinder Setup

25-foot Grinder

25-foot Grinder Setup

ProVAL’s Default 25’ Simulation

• Consistently under predicts Ride Quality reduction

• Consistently overestimates material depth removal for a given head depth

• Why?

– Articulated sub frame not modeled

– Impact of drive wheels not modeled

– Actual effective wheelbase is variable and not modeled (only 25 foot)

ProVAL’s Simulations of Solid Frame Machines

• Consistently predict Ride Quality reduction extremely well

• Consistently predict material depth removal for a given head depth extremely well

• Why?

– All of the machine geometry and dimensions can be accurately accounted for in the simulation models

Grinding Simulation Tips

• Not all grinders can fix all roughness events or bridge encounter roughness

• Geometry of machine dictates what roughness can be corrected

• Use grind / no grind break points to set desired head depth

• Grinding can make some roughness events worse

Grinding Simulation Tips

• Simulation is in 2-D while all bridges exist in 3-D

• Run all wheel paths all lanes of bridge encounter to see if similar grind works for all

• Know exactly where and how long your deck and approach slabs are (event mark profile while collecting data)

• Multiple grinds may be necessary at isolated locations for particularly rough spots

• Simulation is cheap actual grinding is expensive

Practice different grinding scenarios!

Developing the Corrective Plan

• Did I build things that I can’t grind?

– Long or deep dips

• False work let loose

• Bidwell fell off of the rail

• Approach slab settled

• Pavement dips at end of bridge

– Steel Armor installed too high

False Work Issue

High Steel Armor

Developing the Corrective Plan

• Documented all interfaces and distances of pavement, approach slabs, and deck within encounter

• Which grinder/setting is available and/or is capable of correcting the problem

• Layout the plan

– Start/stop locations and corresponding head depths

– Direction of grinds

– Multiple grind locations (if necessary)

Questions

Brian L. Schleppi

ODOT Office of Technical Services

614.752.5745

Brian.schleppi@dot.state.oh.us