LEV VOR TECH SPECS - VOLUME III.pdf
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- Seawall Repair Leeville LA
- Solicitation number
- 6973GH-23-Q-00133
About this file
This document is a solicitation for a seawall repair project in Leeville, Louisiana. The Federal Aviation Administration is seeking a firm-fixed-price construction contract to provide all labor, materials, equipment, and supervision for repairing and performing associated work on the sea wall in Leeville. Interested contractors must be registered in the System for Award Management and submit any required forms by June 16, 2023 to be eligible for award. All questions regarding the project scope of work or plans must be received in writing by June 5, 2023. E-mailed proposals will be accepted until 5:00pm CST on June 16, 2023 and must reference solicitation number 6973GH-23-Q-00133. The selected contractor will be required to adhere to the Federal Aviation Administration's Acquisition Management System in place of the Federal Acquisition Regulation.
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Engineered Earth Armoring System™
ARMORMAX is the most advanced flexible armoring technology available for severe erosion and surficial slope stability challenges. ARMORMAX is composed of High Performance Turf Reinforcement Mat (HPTRM) and Engineered Earth Anchors™ that work together to lock soil in place and protect against hydraulic stresses.
PYRAMAT 75
HPTRM
*Based on a 4-person crew with equipment operator, working 8 hrs per day.
**Based on 6” stone size at 18” depth and 15 tons per dump truck.
Installation Comparison:
ARMORMAX®
vs.
RipRap
Typical placement of 1 acre, or about 5,000 SY, of erosion protection.
***Assuming $25/ton for material, average fuel and equipment costs, and labor as specified above.
*DAYS 5 *DAYS 11
**CONTAINER VAN 1/2 **DUMP TRUCKS 334
***DOLLARS $28 PER SY ***DOLLARS $65 PER SY
Riprapvs.
GAI-LAP
ACCREDITATION
P
RO
UDLY MAD
E
BY PROPEX
IN THE
USA
TOOL GUIDE
A) Anchor Driver (Gas Powered) Description: Used to drive Engineered Earth Anchors to proper embedded depth. Can be used with B1 anchor as well as B2 anchors depending on soil and site conditions.
MV: 1013501
B) Setting Tool JackJaw Description: Used to set B1, B2 & B3 Engineered Earth Anchors and extract drive rods up to ¾” diameter.
MV: 1013516
C) Drive Rod Remover Description: Extracts drive rods ¾” – 1” diameter. Required for jobs using 1” and may be beneficial for jobs using ¾” due to increased pulling power.
MV: 1013672
D) WCUT Wire Cutters Description: Used to cut cable tendons on B1 anchors.
MV: 1007885
E) Large Wire Cutters Description: Used to cut cable tendons on B2 & B3 anchors
MV: 1014073
F) Drive Rod EEA B1 4’ Description: Used to drive B1 anchors to 3’ embedded depth.
MV: 1014728
G) Drive Rod B2 & B3 6’ Description: Used to drive B2 & B3 anchors to 6’ embedded depth.
MV: 1013685
A
D
E
F
G
ARMORMAX Tools
C
6’
B
H I
J
K
L
M
N
O
H) Drive Rod B2 9’ ¾” OD Description: Used to drive B2 & B3 anchors to 9’ embedded depth.
MV: 1010377
I) Heavy Duty Drive Rod B2 9’ 1” OD Description: Used to drive B2 & B3 anchors to 9’ embedded depth in rocky soils or highly compacted conditions.
MV: 1014072
J) Segmented Drive Rod Kit Description: Used to drive B2 & B3 anchors to 9’ embedded depth.
MV: 1014717
K) Measuring Tape Description: Helpful for measuring pin and anchor placement.
L) 4.5” Angle Grinder with Cut Off Wheel Description: Used to cut ancho cable tendons and PYRAMAT fabric.
M) Framing Hammer Description: Helpful for driving washer pins.
N) Pneumatic Palm Driver
Description: More effective way to drive washer pins.
O) Shop Shears
Description: Useful for manuall cutting PYRAMAT fabric.
These additional tools (not sold through
Propex) are suggested for installation and can be found at your local hardware store.
Site Preparation: Grade and compact the failed slope and remove objects that would prevent ARMORMAX from making direct contact with the soil. Excavate a trench at the crest and toe of the slope.
HPTRM Laydown: Unroll the HPTRM on the prepared soil ensuring material has intimate contact with the soil.
Anchor Installation: Anchors should be installed in locations specified for the project.
For complete installation guidelines, please visit PropexGlobal.com.
Vegetation Establishment : Vegetation can be established by broadcast seeding, hydraulic seed application (hydroseeding), or sodding.
ARMORMAX Installation Details
GAI-LAP
ACCREDITATION
P
RO
UDLY MAD
E
BY PROPEX
IN THE
USA
DESIGN AND MAINTENANCE OF GRAVEL ROADS
Course Description
Topics
CHAPTER 1 Introduction: Design and Maintenance of Gravel Roads
Introduction
Understanding Road Cross Section
Basic Road Shaping Principles
Other Road Shaping Considerations
Road Shoulders
Reshaping Surface and Shoulder
Erosion Control
CHAPTER 2: Special Areas of Concern
Dealing with Corrugation
Dealing with Washboarding
Intersections, Bridge Approaches, and Railroad Crossings
Soft and Weak Subgrade and Use of Geosynthetics
CHAPTER 3: Drainage in Gravel Roads Systems
Drainage Ditches
Culverts and Bridges
Underdrains
CHAPTER 4: Surface Gravel
CHAPTER 5: Aggregates
Roadway Preparation Prior to Laying Aggregate
Calculating Quantity of Aggregate
Windrowing, Equalizing, and Spreading the Aggregate
CHAPTER 6: Dust Control and Stabilization
Benefits of Dust control and Stabilization
Good Surface Gravel Combined with Stabilizers
Road Preparation Prior to Stabilizer Application
Applying the Product
CHAPTER 7: Recent Innovations
Innovative Equipment and Methods
Pulverizers and Disks
Moldboard Cutting Edge Options
Grader-Mounted Mixers and Rollers
Electronic Slope Controls
Blading Devices and Crushers
Tractor-Mounted Crushers
CHAPTER 8: Construction Criteria
Standard Requirements
Construction Considerations
Temporary Traffic Control
Guidance on Placing Gravel
CHAPTER 9: When to Pave a Road
DESIGN AND MAINTENANCE OF GRAVEL ROADS
Course Description
Topics
CHAPTER 1 Introduction: Design and Maintenance of Gravel Roads
Introduction
Understanding Road Cross Section
Basic Road Shaping Principles
Other Road Shaping Considerations
Road Shoulders
Reshaping Surface and Shoulder
Erosion Control
CHAPTER 2: Special Areas of Concern
Dealing with Corrugation
Dealing with Washboarding
Intersections, Bridge Approaches, and Railroad Crossings
Soft and Weak Subgrade and Use of Geosynthetics
CHAPTER 3: Drainage in Gravel Roads Systems
Drainage Ditches
Culverts and Bridges
Underdrains
CHAPTER 4: Surface Gravel
CHAPTER 5: Aggregates
Roadway Preparation Prior to Laying Aggregate
Calculating Quantity of Aggregate
Windrowing, Equalizing, and Spreading the Aggregate
CHAPTER 6: Dust Control and Stabilization
Benefits of Dust control and Stabilization
Good Surface Gravel Combined with Stabilizers
Road Preparation Prior to Stabilizer Application
Applying the Product
CHAPTER 7: Recent Innovations
Innovative Equipment and Methods
Pulverizers and Disks
Moldboard Cutting Edge Options
Grader-Mounted Mixers and Rollers
Electronic Slope Controls
Blading Devices and Crushers
Tractor-Mounted Crushers
CHAPTER 8: Construction Criteria
Standard Requirements
Construction Considerations
Temporary Traffic Control
Guidance on Placing Gravel
CHAPTER 9: When to Pave a Road
Design�and�Maintenance�of�Gravel�Roads�� Credits:�8�PDH�
Course�Description� This�eight�hour�engineering�course�addresses�the�maintenance�and�design�of�gravel�roads.�Unpaved�surfaces�make�up�a� sizable�percentage�of�both�domestic�roads,�as�well�as�roads�abroad;�therefore,�the�administration�and�maintenance�of� these�road�systems�can�be�an�enormous�task.�Most�of�the�maintenance�duties�of�these�road�systems�fall�on�local� authorities,�although�much�of�the�remaining�responsibilities�lie�with�state�highway�agencies.� This�course�provides�an�overview�of�the�administration,�maintenance�and�design,�reshaping�and�rehabilitation,�and� construction�considerations�of�gravel�roadway�systems.�Special�topics�include�drainage,�erosion�and�control,�windrows,� superelevation,�as�well�as�other�special�areas�of�concern.� A�thorough�understanding�of�geotechnical�aspects�is�also�very�important�when�dealing�with�unpaved�roadways.�Soil� drainage�and�load�bearing�characteristics,�sampling�and�testing,�use�of�geofabrics�for�soft�and�weak�subgrades,�and� finding�the�correct�mixture�of�sand,�stone,�and�fines�for�base�and�surface�applications�are�topics�that�are�uniquely� characteristic�of�unpaved�roadways.�Learning�one’s�way�around�quarries�and�pits,�as�well�as�knowing�which�types�of� aggregate�will�produce�the�best�road�surfaces�are�essential�skills�for�any�road�construction�administrator.�
Topics� � Gravel�road�maintenance�and�design.� � Road�shaping�principles,�considerations,�as�well�as�the�optimum�road�“crown.”� � Routine�maintenance�and�rehabilitation.� � The�use�of�windrows.� � The�use�of�superelevation�or�banking.� � Road�shoulders�and�the�benefits�of�a�good�mowing�routine.� � The�importance�of�proper�road�drainage�and�erosion�control.� � Surface�and�base�gravel�aggregate�selection:�The�use�of�recycled�materials.� � Types�of�dust�control�stabilizers.� � Innovative�equipment�and�methodologies.� � Motor�grader�operation�and�inspection.� � Aggregate�gradation,�testing,�sampling,�and�analysis�of�soil�conditions,�as�well�as�finding�good�surface�gravel�and� base.� � Special�areas�of�concern�(intersections,�bridge�approaches,�railroads,�driveways,�and�cattle�guards).� � Soft�and�weak�subgrade:�The�use�of�geosynthetic�fabrics�for�weak�subgrade;�classification�of�geosynthetics.� � Dealing�with�corrugation�or�“washboarding.”� � Special�equipment:�Pulverizers,�disks,�rakes,�in�place�crushers,�mixers,�electronic�slope�controls.� � Construction�criteria:�Standards�requirements,�pre�construction,�and�construction�considerations.� � Temporary�traffic�control�(TTC).� � Considerations�for�when�to�pave�a�road�and�when�to�leave�it�“as�is.”� � Stage�construction.�
Chapter�1:�Introduction:��Design�and�Maintenance�of�Gravel�Roads��
Introduction� This�course�is�designed�to�provide�an�overview�of�the�basic�design�and�maintenance�principles�for�gravel�surfaced�roads,� with�guidelines�and�instructions�about�how�the�various�operations�are�performed.�This�course�was�developed�with�a� greater�emphasis�on�the�maintenance�of�gravel�surfaced�roads,�with�basic�design�elements�included.�As�an�engineer,� overseeing�and�administering�of�gravel�road�construction�and�maintenance�projects�will�require�a�basic�understanding�of� many�of�these�principles.� Many�Roads�in�the�U.S.�are�Gravel�
The�U.S.�Department�of�Transportation’s�Bureau�of�Statistics�reported�that�1.42�million�miles�of�roads,�or�35�percent�of� all�roads�in�the�U.S.,�were�unpaved�as�of�2012.�In�some�lesser�developed�countries�of�the�world,�almost�the�entire�road� infrastructures�systems�consist�of�unpaved�dirt�or�gravel�roads.��� Gravel�roads�are�often�considered�to�provide�a�lower�quality�of�service�than�paved�road�surfaces;�yet,�the�low�volume�of� traffic�in�many�rural�areas�does�not�justify�the�expense�of�paving�and�maintaining�hard�surfaced�roads.�� In�many�cases,�gravel�roads�exist�simply�to�provide�a�means�of�transporting�agricultural�goods,�hauling�timber,�or� providing�remote�access�to�recreational�or�residential�areas.�Many�of�these�roads�are�likely�to�remain�unpaved�due�to� low�traffic�volume�or�lack�of�funding�to�adequately�improve�the�subgrade�and�base�layers�required,�prior�to�applying�the� final�paved�layer.�� Quality�Gravel�Road�Maintenance�or�Rehabilitation� A�good�quality�of�road�depends�on�two�basic�elements:�The�proper�use�of�a�motor�grader�(or�another�type�of�grading� device)�and�the�use�of�good�surface�gravel.�Many�gravel�maintenance�or�rehabilitation�problems�can�be�traced�back�to� the�quality,�volume,�and�size�distribution�of�the�gravel�used�on�the�road.�Furthermore,�when�dealing�with�the�issue�of� corrugation,�or�“washboarding,”�the�problem�is�often�perceived�to�be�caused�by�the�grader;�in�actuality,�the�material� itself�is�usually�the�root�of�the�problem.�This�topic�will�be�discussed�later�in�this�course.� Vehicles�Used�on�Gravel�Roads� The�type�of�vehicles�and�equipment�used�on�low�volume�roads�is�another�important�matter�to�consider:�Tire�pressure,� size,�weight,�and�horsepower�of�commercial�trucks�and�agricultural�equipment�can�be�contributing�factors�to� washboarding.�The�damaging�effect�of�larger�and�heavier�vehicles�on�our�paved�roads�is�well�understood�and�requires� the�construction�of�stronger�bases�and�pavements;�however,�the�effect�of�these�vehicles�on�gravel�roads�is�just�as� serious�and�it�is�often�not�recognized.�� The�strength�of�the�subgrade,�as�well�as�the�depth�of�the�material�needed�to�support�heavy�loads,�must�be�considered,� along�with�proper�road�drainage.�For�these�reasons,�much�of�this�course�is�focused�on�construction,�drainage,�surface� gravel,�and�the�stabilization�of�these�roads.�� Innovations�in�Gravel�Road�Maintenance�and�Rehabilitation�� The�last�chapter�of�this�course�covers�innovations�in�the�gravel�road�maintenance�and�rehabilitation�industry.�There�have� been�a�number�of�innovative�solutions�for�stabilizing�roads,�methods�for�controlling�dust,�and�new�types�of�equipment� available�for�maintaining�and�rehabilitating�gravel�roads.�The�use�of�geosynthetics�and�other�alternative�surface� materials�(such�as�recycled�pavement�or�blends�of�recycled�and�virgin�aggregate)�are�now�being�used.��
Understanding�Road�Cross�Section������������� Understanding�the�Gravel�Road�Cross�Section� When�involved�in�gravel�road�maintenance,�one�must�understand�the�correct�shape�of�the�entire�area�within�the�road’s� right�of�way.�Figure�1.2.1,�below,�shows�a�typical�cross�section�of�a�gravel�road.��
Figure�1.2.1�–�Roadway�cross�section.�
To�properly�maintain�a�gravel�road,�these�three�basic�elements�should�be�understood:�
� The�crowned�driving�surface.� � The�shoulder�area�(that�slopes�directly�away�from�the�edge�of�the�driving�surface).� � The�drainage�ditch.�
The�right�of�way�space�allotted�for�the�shoulder�area�and�the�ditch�of�many�gravel�roads�is�often�minimal.�Even�so,�the� basic�shape�of�the�cross�section�must�be�correctly�graded�or�a�gravel�road�will�not�perform�well,�even�under�low�traffic� conditions.� Paved�roads�are�usually�designed,�then�constructed,�with�careful�consideration�given�to�the�correct�shape�of�the�finished� cross�section,�particularly�to�the�surface�and�the�shoulder.�Once�paving�is�finished,�the�road�should�keep�its�shape�for�an� extended�period�of�time.�Gravel�roads,�however,�are�quite�different:�Many�of�them�were�not�constructed�with�the�same� attention�to�design�and�quality�control�during�construction.�Additionally,�gravel�roads�can�easily�rut�or�form�potholes� during�periods�of�prolonged�wet�weather.�During�periods�of�dry�weather,�on�the�other�hand,�traffic�tends�to�displace� gravel�from�the�surface�to�the�shoulder�area���even�to�the�ditch.�� During�routine�maintenance,�the�roadway�surface�and�the�shoulder�should�be�kept�properly�shaped;�keeping�the� foreslope�and�ditch�established�and�shaped�is�required,�as�well.�The�primary�goal�is�to�keep�water�drained�away�from�the� roadway.�Water�that�is�allowed�to�pool�at�any�place�within�the�cross�section�of�the�road,�including�the�ditch,�is�one�of�the� major�reasons�for�the�distress�and�failure�of�a�road.�� Need�for�Alternate�Equipment� At�times,�there�may�be�a�need�for�other�equipment�(such�as�an�excavator)�to�perform�ditch�cleaning�procedures;�this�is� especially�true�in�excessively�wet�conditions.�The�motor�grader�equipment,�however,�must�be�principally�relied�upon�to� do�the�majority�of�the�road�care,�as�limited�budgets�often�do�not�allow�for�the�use�of�extra�equipment�and�manpower�on� the�lower�priority�gravel�roads.�� Heavy�Loads� When�a�gravel�road�is�maintained�properly,�it�will�serve�low�volume�traffic�well�if�much�of�the�traffic�consists�of�light� vehicles.�However,�gravel�roads�will�usually�fail�when�exposed�to�repeated�heavy�loads�–�even�when�shaped�property.�� Wet�Conditions�and�Weak�Subgrade� Failures�generally�occur�in�wetter�conditions.�These�failures�are�due�to�weak�subgrade�strength�and�marginal�gravel� depths,�which�are�common�problems�with�gravel�roads.�The�low�volume�of�normal�traffic�does�not�warrant� reconstruction�to�a�higher�standard.�However,�improper�maintenance�can�also�lead�to�quick�deterioration�of�a�gravel� road���especially�in�wet�weather.�Care�must�always�be�taken�to�maintain�the�proper�crown�and�shape�to�mitigate�these� types�of�failures.�
Figure�1.2.2�–�Poorly�shaped�road�in�a�dry�and�arid�environment.�
The�road�in�Figure�1.2.2�is�located�within�a�desert�region�and�performs�poorly,�even�though�the�average�annual� precipitation�is�less�than�10�inches�per�year.�The�principal�problem�is�a�poor�cross�section�with�no�crown�on�the�surface� and�no�ditches�at�the�edge�of�the�roadway�to�drain�water�from�the�surface�and�away�from�the�road.�
Figure�1.2.3�–�Well�shaped�road�in�a�region�with�considerable�rainfall.�
On�the�other�hand,�the�road�in�the�image�above�(Figure�1.2.3)�is�located�in�a�region�with�a�considerable�amount�of� annual�rainfall;�the�average�annual�precipitation�exceeds�60�inches.�An�adequate�crown�on�the�road�surface�and�ditches� at�the�edge�of�the�roadway�are�effective�in�water�distribution�and�subsequent�road�performance.���
Figure�1.2.4�–�Good�example�of�a�well�shaped�road.��
Above�is�an�example�of�a�gravel�road�with�the�correct�shape�throughout�the�entire�cross�section.�The�road�has�a�driving� surface�with�adequate�crown�that�slopes�directly�to�the�edge�of�the�shoulder.�
Figure�1.2.5�–�Well�drained�road.�
The�foreslope�of�the�road�in�the�above�image�(Figure�1.2.5)�is�also�shaped�very�well,�allowing�drainage�of�water�from�the� road�surface�down�to�the�ditch.�
Figure�1.2.6�–�Gravel�road�with�limited�right�of�way.�
The�image�above�(Figure�1.2.6)�shows�an�example�of�the�proper�way�to�shape�a�roadway�when�the�road�exists�in�an�area� with�a�limited�right�of�way�in�which�to�maintain�the�roadsides.�
Basic�Road�Shaping�Principles� Having�the�Proper�Grading�Equipment� The�motor�grader�is�the�standard�piece�of�equipment�used�in�the�shaping�of�gravel�roads�during�maintenance.�There�are,� however,�other�devices�which�can�work�equally�well.�The�principles�of�establishing�and�maintaining�the�roadway�shape� or�road�geometry�are�the�same,�regardless�of�which�type�of�equipment�is�used.� Other�types�of�equipment�used�to�shape�a�gravel�road:�
� Front�or�rear�mounted�grading�attachments�for�tractors.� � Road�rakes.� � Devices�of�various�designs;�some�specific�to�particular�regions�of�the�country.�
Maintaining�a�Proper�Operating�Speed� When�grading�a�road,�the�operating�speed�used�in�the�blading�operations�must�not�be�fast.�In�most�conditions,�it�is�not� likely�that�the�operator�will�achieve�good�results�when�the�speed�exceeds�3�to�5�mph.�When�the�speed�is�excessive,�the� machine�will�begin�to�“lope,”�or�bounce,�cutting�depressions�and�creating�ridges�in�the�road�surface.��
Figure�1.3.1�–�Depressions�in�the�road�due�to�excessive�operating�speed.�
In�Figure�1.3.1�(above),�the�depressions�that�were�cut�into�this�road�surface�were�the�result�of�operating�the�motor� grader�too�fast.�(The�angles�of�the�depressions�provide�proof�of�this�because�they�match�the�angle�of�the�moldboard.)�
When�the�motor�grader�bounces�due�to�excessive�speed,�the�depressions�resemble�the�effect�from�“washboarding.”� These�types�of�depressions�can�also�result�from�other�causes�(these�causes�will�be�discussed�in�Chapter�2).� Conditions�such�as�moisture,�material�quality,�and�subgrade�stability�will�tend�to�vary;�therefore,�establishing�a� maximum�speed�during�maintenance�can�be�challenging.��Operating�speed�must�be�slow�enough�to�ensure�that�the� machine�remains�stable�and�consistent.� Having�the�Correct�Moldboard�Angle� The�angle�of�the�moldboard�is�also�a�critical�consideration.�Although�angle�is�fixed�on�some�grading�devices,�it�can�be� easily�adjusted�on�motor�graders.�It�is�important�to�keep�the�angle�between�30�and�45�degrees,�as�pictured�below.��
Figure�1.3.2�–�Moldboard�angle.�
It�can�be�difficult�to�recover�loose�aggregate�from�the�shoulder�of�the�roadway�without�spilling�material�around�the� leading�edge�(toe)�of�the�moldboard.�Operating�with�an�insufficient�angle�is�the�main�cause�of�this�type�of�spillage.�When� the�moldboard�is�positioned�at�the�wrong�angle,�it�does�not�allow�enough�surfacing�material�to�be�carried.� The�image�above�(Figure�1.3.2)�shows�a�good�example�of�using�the�angle�and�pitch�of�the�moldboard�to�recover�material� and�move�it�onto�the�roadway�without�spilling�it�around�the�toe�of�the�moldboard.�No�material�is�being�lost�since�the� angle�is�sufficient�to�move�material�across�the�face�of�the�moldboard.�� Moldboard�Pitch� In�addition�to�having�the�correct�moldboard�angle,�it�is�also�important�to�use�the�proper�pitch�or�“tilt”�of�a�moldboard.�� The�image�below�illustrates�moldboard�pitch�or�“tilt”�(how�much�the�moldboard�is�tipped�forward�or�backward).� For�maintaining�gravel�roads,�proper�pitch�will�range�from:�
� Aggressive�cutting�(1);� � To�spreading�(2);� � To�light�blading�or�dragging�action�(3).�
Figure�1.3.3�–�Moldboard�blade�pitch.�
If�the�moldboard�is�pitched�back�too�far,�the�material�will�tend�to�build�up�in�front�of�the�moldboard�and�will�not�fall� forward�and�move�along�to�the�discharge�end�(or�heel)�of�the�blade.��This�also�causes�excess�material�loss�from�the�toe� of�the�moldboard�and�reduces�the�mixing�action�that�is�required�when�recovering�material�from�the�shoulder�and� moving�it�across�the�roadway,�leveling�and�smoothing�the�surface�materials.�� Everyday�traffic�tends�to�loosen�material�from�the�road�surface�and�relocate�it�to�the�shoulder�area�(as�well�as�between� the�wheel�tracks)�over�time.�Everyday�traffic�will�also�cause�the�stone�constituent�to�separate�from�the�sand�and�the� fines.�At�the�same�time,�small�potholes�and�an�uneven�surface�will�develop.�When�performing�routine�maintenance�the� material�must�be�recovered�and�mixed�again�as�it�rolls�along�the�face�of�the�moldboard�to�restore�good�surface�shape.�
Figure�1.3.4�–�Moldboard�is�pitched�too�far�forward.�
When�the�moldboard�is�pitched�too�far�forward,�it�will�accomplish�little�more�than�light�dragging�and�does�not�allow� enough�material�to�be�carried�for�good�maintenance�(Figure�1.3.4,�above).� Likewise,�when�the�moldboard�is�pitched�too�far�back�(Figure�1.3.5,�below),�it�simply�pushes�material�and�does�not�allow� it�to�fall�forward�and�move�across�the�moldboard.��
Figure�1.3.5�–�Moldboard�is�pitched�too�far�back.�
Figure�1.3.6�–�Correct�pitch�of�moldboard�for�most�maintenance�operations.�
Other�Road�Shaping�Considerations� Motor�Grader�Stability� Keeping�a�machine�stable�during�grading�can�occasionally�can�be�difficult,�especially�while�carrying�a�light�load�of� material.�Counteracting�machine�bouncing,�or�“loping,”�requires�experience�when�finding�the�cause�and�determining�a� solution.�If�a�motor�grader�begins�to�rock�from�side�to�side,�called�“duck�walking,”�it�is�usually�the�result�of�having�a�blade� angle�that�closely�matches�the�angle�(from�corner�to�corner)�of�the�tires�on�the�rear�tandem�axles.� The�following�are�several�solutions�to�stabilize�the�grader:��
� Stopping�and�adjusting�the�moldboard�angle�slightly;�then�slowly�resume�blading.� � Reducing�the�speed�can�also�eliminate�the�loping�effect�of�a�machine.� � Varying�the�tire�inflation�pressures�can�help�stabilize�a�machine.� � Leaning�the�front�wheels�in�the�direction�that�the�material�is�being�moved.��
Use�of�Ballast�in�Front� Adding�ballast,�or�extra�weight,�at�the�front�of�the�grader�may�also�help.�Iron�weights�mounted�to�the�wheels�or�frame,� or�liquid�materials�such�as�water�and�calcium�chloride�solution�(placed�in�the�tires),�can�all�serve�as�ballasts.��Ballast� consisting�of�the�water�and�calcium�chloride�solution�is�the�type�of�liquid�ballast�that�is�most�commonly�used.�Filling�the� tires�to�about�70�percent�capacity�is�done�to�increase�traction,�weight,�and�stability�of�the�grader.�Some�constant�or� severe�stability�problems�may�also�be�caused�by�equipment�issues.� Frame�Articulation� Articulation�refers�to�a�grading�machine�with�a�jointed�main�frame.�This�assists�in�steering�the�machine,�allowing�it�to� work�in�an�angled�configuration,�yet�still�move�forward�in�a�straight�line.� Practically�all�modern�motor�graders�come�equipped�with�frame�articulation.�It�is�recommended�to�slightly�articulate�the� machine�for�stability,�even�in�common�maintenance�operations.�More�aggressive�articulation�allows�a�greater�reach�with� the�moldboard.�� For�example,�the�front�wheels�can�be�placed�out�on�the�shoulder�to�better�recover�material�with�the�moldboard�while� keeping�the�rear�axles�on�the�roadway�for�stability.�There�are�too�many�applications�for�articulation�to�cover�in�this� course,�but�learning�to�use�this�feature�is�recommended�to�properly�perform�many�routine�maintenance�and� rehabilitation�operations.�
Figure�1.4.1�–�Illustration�of�an�articulated�motor�grader�and�definitions�of�terms�specific�to�the�moldboard.�
Use�of�Windrows� In�regions�that�are�particularly�arid�or�semi�arid,�it�is�a�commonly�accepted�practice�to�leave�a�small�maintenance� windrow�near�the�edge�of�the�roadway.�This�practice�involves�leaving�a�small�amount�of�material�to�be�picked�up�on�the� next�pass�and�worked�back�across�the�road�for�filling�small�depressions.��
Figure�1.5.1�–�Example�of�a�light�windrow�being�placed�at�the�edge�of�the�roadway�
In�other�regions,�however,�windrows�are�disapproved�of�and�road�maintenance�departments�may�have�policies� prohibiting�their�use.�This�is�often�the�case�in�regions�that�have�narrow�rights�of�way�and�narrow�driving�surfaces.� Additionally,�windrows�are�discouraged�in�areas�of�high�rainfall�due�to�the�restriction�of�drainage�caused�to�the�shoulder� and�ditch.�� When�a�jurisdiction�does�allow�the�use�of�windrows,�however,�it�is�important�to�keep�them�to�a�minimum.�The�windrow� should�also�be�placed�near�the�edge�of�the�roadway�to�allow�as�great�a�width�for�travel�as�possible.��
Figure�1.5.2�–�Excessive�amount�of�windrow.�
It�can�be�difficult�to�distinguish�between�too�much�windrow�and�not�enough�windrow.�The�windrow�in�the�above�image� (Figure�1.5.2)�is�excessive�and�should�not�have�be�left�in�the�road.�This�is�poor�practice,�even�on�a�low�volume�road.� Multiple�passes�should�have�been�made�with�the�grader�or�another�mechanism�(such�as�a�disk)�to�work�the�vegetation� out�of�the�windrow,�as�well�as�to�break�up�the�chunks�of�sod�so�that�more�material�could�be�spread�onto�the�roadway.�
Crown� It�can�sometimes�be�difficult�to�distinguish�between�“inadequate”�and�“excessive”�when�establishing�the�proper�crown� on�a�gravel�surface.�Gravel�roads�that�have�no�crown�can�be�extremely�problematic.��
Figure�1.6.1�–Road�with�inadequate�crown.��
No�Crown�Equals�no�Drainage� As�illustrated�in�the�image�above�(Figure�1.6.1),�potholes�and�corrugation�tend�to�form�as�a�result�of�the�lack�of�a�crown� for�draining�water�from�the�road�surface.�A�proper�crown�ensures�water�will�drain�off�of�the�roadway�surface�during�a� rain�event.�Without�it,�water�will�quickly�collect�on�the�road�surface�during�a�rain�event�or�a�snow�melt�and�will�soften� the�crust.�Water�retained�in�the�roadway�surface�can�lead�to�rutting,�which�can�extend�down�into�the�subgrade;� therefore,�a�properly�drained�gravel�road�must�have�a�sufficient�or�adequate�crown.� Excessive�Crown�can�be�Unsafe� Excessive�crown�in�the�road�surface�can�lead�to�an�unsafe�condition:�Drivers�may�have�difficulty�remaining�in�their�lane� and�may�begin�to�feel�a�slight�loss�of�control�as�their�vehicle�wants�to�slide�toward�the�shoulder.��
Figure�1.6.2�–�Road�with�too�much�crown.�
The�road�in�the�image�above�(Figure�1.6.2)�is�wide�enough,�but�it�is�obvious�from�the�wear�patterns�that�most�drivers�use� the�middle�of�the�road�for�driving.�This�is�the�result�of�an�excessive�crown�which�is�causing�the�drivers�to�veer�off�to�the� side�when�using�their�own�lanes.��
Figure�1.6.3���Narrow�roads�with�confining�right�of�ways�still�require�a�proper�crown.�
There�is�the�additional�risk�of�driving�on�gravel�roads�with�an�excessive�crown�in�regions�that�experience�snow�and�ice� cover.�This�adds�to�the�risk�of�sliding�off�the�road�due�to�the�slick�and�slippery�conditions.�� The�Recommended�Crown� A�crown�at�or�near�1/2�inch�of�crown�per�foot�(or�approximately�four�percent)�on�the�cross�slope�is�highly�recommended.� While�it�is�virtually�impossible�to�maintain�an�absolutely�uniform�crown,�minimal�deviation�is�recommended�and�is�not�to� exceed�six�percent�in�any�condition.�� Crown�Gauges�and�Electronic�Slope�Control� Gauges�that�can�be�mounted�in�the�grader�cab�are�available�to�help�the�operator�control�crown;�there�are�also�electronic� slope�controls�available.�Slope�controls�are�normally�found�in�construction�operations,�but�can�be�used�for�gravel�road� reshaping�and�maintenance�applications.� Parabolic�Crown� Another�problem�with�crown�is�the�parabolic�crown.�The�ideal�surface�shape�is�a�straight�line�from�the�shoulder�up�to� the�center�of�the�road,�which�gives�the�road�the�same�shape�as�the�roof�of�a�house.�However,�this�shape�can�sometimes� become�rounded.�The�engineering�term�for�this�rounding�of�the�surface�is�“parabolic�crown,”�and�is�virtually�always�a� problem.�The�reason�is�that�the�middle�portion�of�the�road�will�have�considerably�less�crown�than�the�outer�edges;� consequently,�water�will�not�drain�from�the�middle�and�potholes�and�ruts�will�develop.�
Figure�1.6.4�–�Roadway�with�a�parabolic�crown.�
In�Figure�1.6.4,�the�outer�edge�of�the�roadway�slopes�too�much�due�to�gouging�at�the�edges,�while�the�center�of�the�road� remains�fairly�flat.� The�greatest�cause�of�a�parabolic�crown�is�excess�wear�at�the�center�of�the�cutting�edge.�This�is�normal�wear�and�will� vary�with�types�of�gravel,�width�of�road,�wheel�path�location,�and�other�factors.�An�effort�should�be�made�to�avoid� creating�parabolic�shapes�on�a�roadway�by�keeping�the�cutting�edge�straight.�To�do�so,�a�cutting�torch�can�be�used�to� straighten�the�cutting�edge�whenever�1/2��to�3/4�inch�or�more�of�center�wear�exists.�Also�using�a�thicker,�harder�section� of�cutting�edge�in�the�middle�of�the�moldboard�will�help�to�reduce�the�excess�center�wear.�
Figure�1.6.5�–�Cutting�edge�with�center�wear.�
Using�Carbide�Tipped�Bits�and�Inserts� Another�solution�to�the�problem�of�parabolic�crown�is�to�use�carbide�tipped�bits�on�the�cutting�edge,�which�are� extremely�wear�resistant�and�help�to�drastically�reduce�center�wear.�Also�carbide�insert�or�carbide�faced�cutting�edges� that�are�wear�resistant�can�be�used.�Although�they�are�expensive,�these�edges�often�have�wear�life�that�far�exceeds� carbon�steel�or�through�hardened�cutting�edges.��This�makes�them�cost�effective�over�the�life�of�the�blade.��
Figure�1.6.6�–�Diagram�of�a�proper�road�crown.�
Figure�1.6.7�–�Well�crowned�road.�
The�road�in�the�image�above�(Figure�1.6.7)�performs�well�because�of�good�crown�and�good�gravel�quality,�even�though�it� is�located�in�a�wet�region.�
Road�Shoulder� The�road�shoulder�serves�several�essential�functions:�It�supports�the�edge�of�the�traveled�portion�of�the�roadway,�and�it� also�provides�a�safety�area�for�drivers�to�regain�control�of�vehicles,�if�forced�to�leave�the�road�surface.��
Figure�1.7.1�–�Good�example�of�a�road�shoulder.�
These�photos�(Figures�1.7.1,�1.7.2)�show�good�examples�of�gravel�shoulders�that�match�the�edge�of�the�roadway�well� and�drain�water�to�the�ditch.�
Figure�1.7.2�–�Another�good�example�of�road�shoulder.�
The�road’s�shoulder�also�contributes�to�the�effectiveness�of�a�road�drainage�system�and�carries�water�away�from�the� road�surface�toward�the�foreslope�and�into�the�ditch.�The�shape�of�the�shoulder�is�critical�in�order�to�perform�these� functions.�The�shoulder�should�first�meet�the�edge�of�the�roadway�at�the�same�elevation.�In�other�words,�the�shoulder� should�begin�no�higher�or�no�lower�than�the�edge�of�the�roadway.�The�low�shoulder,�or�drop�off�(a�safety�hazard),�is� eliminated�by�maintaining�this�shape.��It�also�improves�roadway�edge�support.��The�other�extreme,�a�high�shoulder,� should�also�be�avoided�as�it�prevents�proper�drainage.��� Gravel�roads�in�some�regions,�particularly�those�with�narrow�rights�of�way,�are�recognized�to�have�little�shoulder�area.�In� some�cases,�the�edge�of�roadway�is�actually�the�beginning�of�the�foreslope�down�into�the�ditch.�But�again,�it�is�important� that�there�is�not�a�steep�drop�off�or�a�ridge�of�soil�to�block�drainage.�Maintaining�shoulders�is�a�critical�part�of�gravel� road�maintenance.� High�Shoulders�(Secondary�Ditches)� A�condition�known�as�“high�shoulders”�can�occur�along�gravel�roads�almost�anywhere�that�people�travel.�Slang�terms� such�as�“berms”�or�“curbs”�are�used�in�the�field�to�refer�to�this�condition.�The�engineering�term�for�this�condition�is� “secondary�ditch,”�and�it�is�a�good�description�of�the�situation.�When�a�gravel�road�develops�a�high�shoulder,�it�can� restrict�the�surface�water�from�draining�into�the�designed�ditch�and�in�turn,�leads�to�several�problems.��
Figure�1.7.3�–�Severe�secondary�ditch.�
The�image�above�is�an�example�of�a�severe�secondary�ditch�that�was�caused�by�the�buildup�of�material�at�the�road� shoulder,�and�has�eroded�away�during�heavy�rain.� In�relatively�level�terrain,�the�water�collects�at�the�shoulder�line�and�seeps�into�the�subgrade,�often�causing�the�whole� roadway�to�soften.�In�rolling�and�rugged�terrain,�the�water�quickly�flows�downhill�along�the�secondary�ditch,�often� eroding�away�a�large�amount�of�gravel���even�eroding�the�subgrade.�� This�also�creates�a�serious�safety�hazard.�There�are�many�reasons�to�work�hard�to�eliminate�the�high�shoulder�or� secondary�ditch.� Causes�of�High�Shoulders�(Secondary�Ditches)� There�are�several�conditions�that�cause�secondary�ditches�to�form:�They�can�develop�from�improper�maintenance,�such� as�losing�material�from�the�toe�of�a�grader’s�moldboard�that�builds�up�a�high�shoulder,�or�from�cutting�too�deep�at�the� shoulder�line�with�the�toe�of�the�moldboard.��
Figure�1.7.4�–�Severe�secondary�ditch�caused�by�gouging�from�the�motor�grader�moldboard.�
This�is�a�particular�problem�when�the�cutting�edge�is�not�kept�reasonably�straight.�But�there�are�many�other�causes.�For� example,�excessive�“whip�off”�of�loose�material�from�fast�traffic�tends�to�build�up�along�the�shoulder�line.�� Heavy�Loads�with�Weak�Subgrades� Heavy�loads�on�gravel�roads�with�weak�subgrades�can�also�cause�this�condition.�When�heavy�vehicles�must�travel�near� the�shoulder�while�meeting�other�vehicles,�the�roadway�can�rut�while�the�shoulder�area�shoves�upward.�Another�cause� of�this�is�the�buildup�of�sand�in�northern�regions�where�winter�ice/snow�control�requires�some�winter�sanding� operations�on�gravel�roads.��
Figure�1.7.5�–�Badly�damaged�and�flooded�road�section.�
Repeated�heavy�haul�and�poor�maintenance�has�destroyed�the�shape�of�this�road�in�the�image�above�(Figure�1.7.5).� Obstructions�within�the�shoulder�drainage�can�be�the�biggest�contributor.�It�can�be�difficult�to�completely�eliminate� secondary�ditches;�however,�every�effort�should�be�made�to�reduce�the�occurrences�to�a�minimum.�
Road�Shoulders�(Continued)� Recovering�and�Spreading�on�Roadway� More�than�one�pass�will�generally�be�required�to�recover�material�from�high�shoulders�if�a�motor�grader�is�the�only�piece� of�equipment�used�on�the�job.�This�process�is�often�referred�to�as�“pulling�the�shoulder.”��If�there�is�little�or�no� vegetation�on�the�shoulder,�simply�extend�the�moldboard�out�into�the�shoulder�material�and�begin�to�pull�it�onto�the� roadway.�If�the�amount�of�material�is�light,�you�may�be�able�to�do�this�in�one�pass.�The�material�recovered�is�often�good� gravel�that�needs�to�be�returned�to�the�roadway�surface.�
Figure�1.8.1�–�Recovering�loose�material.�
In�Figure�1.8.1�(above),�a�motor�grader�moldboard�is�being�used�to�recover�loose�material�and�move�it�back�on�the� roadway�to�restore�shoulder�drainage.� Breaking�up�Sod�and�Vegetation�in�Recovered�Material� Quite�often,�the�material�pulled�out�onto�the�roadway�from�the�shoulder�is�hard�to�spread�because�of�the�vegetative� material�it�contains.�Multiple�passes�with�the�grader�will�be�required�to�get�the�job�done.��
Figure�1.8.2�–�Grader�mounted�disks.�
A�shop�fabricated�disk�mounted�on�a�grader�(Figure�1.8.2,�above)�and�a�small�disk�mounted�on�a�tractor�(Figure�1.8.3,� below)�are�both�effective�when�breaking�up�clumps�in�material�recovered�from�the�shoulder.�
Figure�1.8.3���Disks�used�to�process�material�recovered�from�the�shoulder�to�be�spread�back�on�the�road.�
Figure�1.8.4�–�Tractor�mounted�disks.�
Figure�1.8.5�–�Small�pulverizer�used�to�break�up�clumps�in�the�windrow.�
Remove�Substandard�Material� Recovered�material�from�a�high�shoulder�is�not�always�suitable�to�be�reused�on�the�roadway.�It�may�be�best�to�cut�the� material�loose,�pull�it�onto�the�roadway,�load�it,�and�remove�it.�Although�this�can�be�costly,�it�is�better�to�remove�it�than� to�place�it�on�the�surface�and�contaminate�the�existing�gravel�with�trash,�non�graded�rock,�vegetation,�and�organic�soil.��
Figure�1.8.6�–�Contaminated�roadway.�
Figure�1.8.6�shows�material�removed�from�a�small�V�ditch�that�is�coarse�and�contaminated�with�soil�that�is�not�usable�on� the�roadway.�It�should�be�removed�prior�to�placing�new�surface�gravel.�
If�a�road�is�scheduled�to�be�re�graveled,�this�is�an�excellent�time�to�perform�shoulder�work�to�get�the�roadway�back�into� good�shape.�This�is�much�more�involved�than�routine�maintenance;�signs�should�be�placed�to�warn�motorists�about� roadwork�being�done.�It�is�recommended�to�close�the�section�of�road�being�worked�on,�if�possible,�to�avoid�the�problem� of�needing�to�maintain�traffic�throughout�the�project.�
Benefits�of�Mowing� It�is�much�easier�to�accomplish�even�routine�operations�if�the�high�shoulder’s�grass�and�vegetation�is�mowed�ahead�of� time.��When�grass�or�other�vegetation�grows�high�along�the�edge�of�the�roadway,�it�becomes�difficult�to�maintain�a� clean,�uniform�shoulder�line.�It�is�particularly�important�to�cut�back�heavy�vegetation�(as�in�Figures�1.9.1�and�1.9.2,� below),�even�to�make�minor�improvement�on�the�shoulder.��
Figure�1.9.1�–�Road�with�heavy�vegetative�growth�along�the�shoulders.�
Figure�1.9.2�–�High�grass�interfering�with�grading.�
Mowing�in�Northern�Regions� The�cost�of�mowing,�however,�is�often�offset�by�reduced�costs�for�other�maintenance�and�safer�roads.�There�is�another� great�benefit�of�mowing�in�the�northern�plains:�By�removing�the�standing�vegetation,�drifting�snow�will�not�be�trapped� on�the�roadway,�and�will�result�in�drastically�reduced�snow�removal�costs.�� Mowing�Equipment� The�best�equipment�for�this�work�is�rotary�or�flail�mowers.��Both�do�a�good�job�of�shredding�the�vegetation�and�are�not� as�easily�damaged�or�plugged�by�roadside�trash.�
Figure�1.9.3�–�Left�side�of�the�road�shows�well�maintained�vegetation.��
Notice�the�dramatic�difference�in�the�road�shoulders�in�Figure�1.9.3.�It�becomes�so�much�easier�to�recover�gravel�that� has�drifted�to�the�edge�of�the�roadway�when�the�vegetation�has�been�cut�cleanly.�
Rehabilitation� Gravel�roads�are�generally�maintained�by�routine�blading�and�adding�gravel�as�needed,�either�by�“spot�graveling”�or�re� graveling�entire�sections.�Almost�any�gravel�road,�however,�will�gradually�begin�to�show�distress�over�time�and�will� require�more�involved�rehabilitation�to�fix���rather�than�strictly�routine�maintenance.�� The�most�common�problems�that�develop�are�“berms,”�or�secondary�ditches.�These�build�up�along�the�shoulder�line� from�the�shifting�of�material�from�the�surface�to�the�shoulder�area�and�even�onto�the�foreslope�of�the�grade.�Berms�are� caused�by�gravel�being�displaced�by�traffic,�winter�plowing�operations,�erosion�of�material�during�heavy�rain,�and� sometimes�from�poor�routine�blading�techniques.�� This�scenario�often�causes�major�problems�with�drainage.�Frequent�use�by�heavy�trucks�or�equipment�can�also�damage� the�cross�section.�At�certain�intervals,�virtually�every�gravel�road�requires�some�major�rehabilitation.�This�involves� reshaping�not�only�the�road�surface,�but�the�shoulder�area�and�possibly�the�foreslope�and�ditch�as�well.��
Figure�1.10.1�–�Road�section�heavily�damaged�during�a�local�construction�project�(in�wet�conditions).�
Depending�on�the�extent�of�work�needed�to�reestablish�a�good�cross�section�on�the�roadway,�this�work�may�be� accomplished�with�motor�graders�only.�Compaction�equipment�is�always�helpful�if�it�is�available;�loaders�or�excavators� and�trucks�will�be�needed�if�material�must�be�removed.�
Reshaping�Surface�and�Shoulder� Motor�Grader�
Many�problems�with�surface�and�shoulder�shapes�can�be�corrected�by�solely�using�the�motor�grader.�Spring�is�the�best� time�for�this�type�of�work�as�there�is�minimal�vegetative�growth�and�moisture�is�often�present.�The�reshaping�of�the� driving�surface�and�the�road�shoulder�can�be�done�by�cutting�material�with�the�motor�grader�and�relaying�it�to�the� proper�shape�and�crown.�� Pneumatic�Rollers� If�possible,�the�use�of�a�roller�for�compaction�will�greatly�improve�the�finished�surface�and�will�leave�a�denser,�stronger,� and�smoother�surface�that�will�be�easier�to�maintain.�Pneumatic�(rubber�tired)�rollers�are�most�often�used�for�the� compaction�of�gravel;�these�rollers�are�sometimes�mounted�on�the�motor�grader.�� Drum�Rollers� Smooth,�steel�drum�rollers�are�sometimes�used;�however,�good�surface�gravel�needs�to�have�a�cohesive�or�binding� characteristic.�This�type�of�material�can�easily�stick�to�a�steel�roller�making�it�difficult�to�use,�especially�when�moisture�in� the�gravel�is�at,�or�above,�optimum.�
Figure�1.11.1�–�Completely�rehabilitated�road�section.�
The�image�above�(Figure�1.11.1)�shows�the�same�road�as�shown�previously,�following�complete�surface�and�shoulder� reshaping,�as�well�as�new�surface�gravel�added.�� Reshaping�the�Entire�Cross�Section� A�combination�of�any�or�all�of�these�calls�for�major�reshaping:�
� Severe�rutting.� � Loss�of�crown.� � Gravel�loss.� � Deep�secondary�ditches.�
This�type�of�damage�often�occurs�after�a�gravel�road�has�been�subjected�to�unusually�heavy�hauls,�especially�if�these� hauls�occurred�during�wet�weather.�Water�retention�throughout�the�roadway�structure�will�compound�the�problem.�� Major�reshaping�often�must�be�done�on�the�entire�cross�section:�It�may�be�necessary�to�perform�immediately,�regardless� of�the�vegetative�growth.�This�requires�a�much�greater�effort�than�routine�maintenance,�and�often�the�use�of�motor� graders,�disks,�pulverizer�mixers,�and�rollers.��(These�are�not�always�handy,�but�when�they�are�available,�they�help�to� make�the�job�easier.)�It�is�important�to�rebuild�a�uniform�cross�section�and�pay�attention�to�restoring�good�drainage.� Good�surface�gravel�should�be�replaced�only�after�the�previously�mentioned�tasks�are�completed.��
Figure�1.11.2�–�Excellent�roadway�reshape�done�with�only�motor�graders,�a�roller�and�water�truck.�
Erosion�Control� When�major�reshaping�occurs�outside�the�road�surface�area,�the�soil�beneath�the�vegetative�cover�will�be�left�exposed.� This�will�undoubtedly�lead�to�the�erosion�of�that�soil.�� This�problem�may�not�be�affected�in�arid�and�semi�arid�areas,�as�much�as�areas�that�receive�frequent�rains,�have�rolling� or�rugged�terrain,�and�have�highly�erodible�soils.�Issues�such�as�sedimentation�transport,�caused�by�the�erosion,�can� cause�a�range�of�secondary�problems.�� When�vegetative�cover�is�disturbed,�there�are�added�concerns,�such�as:��
� Clogged�culverts.� � Blocked�ditches.�� � Pollution�of�streams�and�lakes.�� � Eroded�slopes�(which�can�shorten�the�life�of�improvements).� � Damage�to�the�environment.� � Violations�of�environmental�regulations�bringing�considerable�penalties�and�fees.�
When�planning�for�gravel�road�improvements,�established�remediation�methods�must�be�used�for�reducing�or� eliminating�erosion�and�sedimentation�transport:�
• Be�alert�for�seasonal�conditions�when�frequent�and�heavy�rainfall�can�be�expected.�
• Avoid�reshaping�during�these�rainy�periods,�if�possible.��
• Minimize�the�amount�of�disturbed�areas�to�limit�the�risk�of�soil�erosion.�
• Delimit�the�work�boundaries�and�prohibit�work�crews�from�too�much�activity�beyond�those�limits.�
• Stabilize�disturbed�areas�with�seeding,�mulching,�erosion�control�blankets,�and�other�methods.�
• Because�removing�vegetative�cover�generally�increases�the�volume�and�velocity�of�water�runoff,�action�must�be� taken�to�minimize�the�flow�and�quantity�of�the�runoff.��
• Keep�slopes�as�shallow�or�gentle�as�possible.��
• Keep�ditch�slope�as�gentle�as�possible.��
• Shorten�drainage�runs�and�work�to�re�establish�vegetative�cover�as�soon�as�possible,�following�the�work.��
• Do�not�allow�sedimentation�to�be�transported�beyond�the�work�boundaries.��
• Sediment�can�be�retained�by�filtering�the�runoff�as�it�flows�(as�through�a�silt�fence).�
• Utilize�ditch�“checks”�to�retain�and�settle�out�particles�of�sediment�within�the�flow�of�runoff�in�the�ditches.�
• Ensure�that�channels�haven’t�formed�in�ditch�bottoms�or�on�slopes,�or�around�and�beneath�erosion�controls.��
• Be�aware�of�any�damage�to�control�measures;�inspect�for�sedimentation�transport�beyond�the�boundaries,� following�heavy�rain�events.�
Figure�1.12.1�–�Example�of�basic�erosion�control�measures�following�a�gravel�road�reshaping.�
Chapter�2:�Special�Areas�of�Concern�
Dealing�with�Corrugation� Corrugation�or�“Washboarding”� There�are�unique�situations�in�gravel�road�maintenance�that�are�not�encountered�when�dealing�with�paved�roads;�these� situations�can�be�found�on�nearly�all�gravel�roads.�The�image�below�(Figure�2.1.1)�shows�the�condition�of�corrugation,�or� “washboarding.”�� Roadway�corrugation�is�caused�by�the�following:�
� Lack�of�moisture.� � Hard�acceleration.� � Aggressive�braking.� � Poor�quality�gravel.�
Figure�2.1.1�–�Example�of�corrugation�or�“washboarding.”�
Corrugation�is�the�most�commonly�found�problem�on�gravel�roads.�It�can�be�annoying�to�drive�on,�damaging�to�vehicles,� and�potentially�dangerous�for�drivers�if�it�causes�a�loss�of�vehicle�control.�Motor�graders�are�often�assumed�to�be�the� cause�of�corrugation;�however,�they�are�seldom�to�blame.�� There�are�four�primary�causes�of�corrugation/washboarding:�
� The�driving�habits�of�people.� � Lack�of�moisture.� � Poor�quality�of�gravel.� � Lack�of�crown�on�the�surface.�
Figure�2.1.2�–�Angled�corrugation�is�a�sign�of�motor�grader�related�corrugation.�
The�image�above�(Figure�2.1.2)�shows�a�form�of�washboarding�appearing�at�an�angle�across�the�roadway.�This�is�caused� by�excess�grader�speed�and�lack�of�crown,�with�ridges�and�depressions�occurring�2�to�3�feet�apart.� 1.)�Driving�habits�� �The�effects�of�driving�habits�are�clearly�evident�when�washboarding�is�found�at�intersections,�on�steep�inclines,�or� before�and�after�sharp�curves,�as�well�as�occasionally�near�driveways.�All�are�places�where�drivers�tend�to�accelerate� hard�or�brake�aggressively.�This�is�one�of�the�primary�causes�of�washboarding;�some�situations�can�occur�along�the� entire�road�section,�especially�when�traffic�speed�is�high.��
Figure�2.1.3�–�Transition�from�gravel�to�paved�surface�–�prone�to�developing�washboard�or�potholes.�
2.)�Lack�of�Moisture�� Dry�conditions�can�promote�washboard�formation;�additionally,�prolonged�dry�weather�can�aggravate�the�problem.�This� is�because�the�crust�that�forms�on�the�surface�of�a�good�gravel�road�will�tend�to�loosen�in�dry�weather,�allowing�the� stone�and�sand�sized�particles�to�loosen,�or�“float.”�The�material�can�easily�align�itself�into�the�washboard�pattern� beneath�the�traffic.�
Figure�2.1.4�–�Good�practice�is�to�loosen,�mix�and�reshape�gravel�in�a�washboard�prone�area�while�moist.�
Figure�2.1.5�–�Cutting�edge�with�carbide�bits���effective�in�loosening�washboard�areas.�
Both�driving�habits�and�lack�of�moisture�are�situations�that�are�beyond�the�control�of�equipment�operators�and� construction�administrators.�� 3.)�Poor�Gravel�Quality� Good�quality�gravel�requires�the�right�blend�of�stone,�sand,�and�fines.�The�stone�should�be�fractured�and�the�fine�sized� particles�should�have�a�binding�characteristic,�technically�called�“plasticity.”�This�type�of�gravel�resists�washboarding�and� will�reduce�the�problem�significantly.�Good�quality�surface�gravel�will�be�thoroughly�discussed�in�Chapter�4�of�this� course.� 4.)�Lack�of�Crown� If�water�cannot�drain�from�the�roadway�surface�and�corrugation�begins�to�form,�the�water�will�quickly�accumulate�in�the� depressions�and�soften�that�surface�area.�Traffic�will�then�make�the�depressions�deeper�as�tires�strike�the�softened�and� moist�depressions,�forcing�aggregate�out�of�the�depressions�and�up�into�increasingly�larger�ridges.�� Dealing�with�Washboarding� Nearly�all�gravel�will�eventually�develop�some�form�of�washboard�under�repeated�traffic.�The�key�is�to�strive�to�keep�the� gravel�constituents�blended.�In�dry�conditions,�however,�the�road�can�only�be�smoothed�temporarily.�In�wet�conditions,� it�is�recommended�to�promptly�rework�these�areas�before�they�become�excessive.�� The�material�should�be�cut�to�a�depth�of�one�inch�or�more�below�the�depressions,�then�mixed�and�relayed�to�the�proper� shape.�Using�the�machine�to�apply�wheel�compaction�to�the�loosened�material�will�help�reform�the�crust;�using�a�roller� will�improve�the�compaction.� Even�with�the�best�of�maintenance,�washboarding�can�never�be�completely�eliminated.�The�key�to�keeping�it�in�check�is� to�use�quality�gravel�with�a�good�binding�characteristic.�Also,�test�the�existing�surface�gravel�and�add�material�on�the� roadway�to�modify�it�to�a�suitable�gradation�and�plasticity,�thoroughly�mixing�it�with�the�motor�grader.�Trouble�spots�can� be�reshaped�when�moisture�is�present�and�most�roads�will�perform�quite�well�with�limited�blade�maintenance.�� If�a�motor�grader�actually�causes�washboarding,�it�is�almost�always�the�result�of�running�it�at�too�great�of�a�speed.�The� ridges�and�depressions�will�be�spaced�further�apart�and�will�form�at�an�angle�across�the�roadway�matching�the�angle�of� the�moldboard.�The�solution�to�this�problem�is�simply�to�reduce�the�operating�speed.�Another�problem�can�be�improper� tire�inflation�pressure�or�defective�tires:�This�will�cause�a�motor�grader�to�bounce�or�otherwise�operate�in�an�unstable� manner.�Corrugation�based�on�motor�grader�issues�is�rare�since�most�washboarding�appears�perpendicular�to�the� direction�of�vehicle�travel.�
Intersections,�Bridge�Approaches,�and�Railroad�Crossings� Intersections� There�is�an�important�distinction�to�be�aware�of�when�shaping�gravel�surfaced�intersections:�Is�the�intersection� controlled�or�uncontrolled?�(Meaning,�does�traffic�have�to�stop�or�yield�at�the�intersecting�roads.)�
Figure�2.2.1�(below)�illustrates�the�proper�shape�of�a�controlled�intersection;�Figure�2.2.2�shows�an�uncontrolled� junction.��
� Controlled���The�primary�road�on�which�traffic�passes�through�should�retain�its�crown,�and�the�intersecting�roads� should�have�crown�gradually�eliminated�beginning�approximately�100�feet�before�the�intersection.��At�the�point� of�the�intersection,�the�side�roads�are�virtually�flat�to�match�the�primary�road.��
� Uncontrolled���When�the�intersection�is�uncontrolled,�the�roads�should�all�have�the�crown�gradually�eliminated�…
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