Surface Drainage Crown (flat A shape) c Dirt & Gravel: 1/2” - 3/4” per foot (4 - 6 inches in 10...
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Transcript of Surface Drainage Crown (flat A shape) c Dirt & Gravel: 1/2” - 3/4” per foot (4 - 6 inches in 10...
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Surface DrainageCrown (flat A shape)Dirt & Gravel: 1/2 - 3/4 per foot(4 - 6 inches in 10 feet)
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Surface DrainageSuperelevated Roadway (Curves)Dirt & Gravel: 1/2 - 3/4 min. per foot
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Surface Drainage - ShouldersFlush with roadAvoid shoulder drop offSlightly steeper cross slopeAvoid secondary ditchesSupports roadwayAllows water to flow further away from road
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Drainage SystemsWrongRightCrownSurface MaterialDitchShoulderSubgradeBaseSurface MaterialSubgradeBase
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Subsurface DrainageFree draining road base beneath the surfaceCollector systems comprised of perforated pipe surrounded by well-graded aggregate with an outlet pipe or other prefabricated systems
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SubdrainsRoadShoulderSubdrainWell-graded aggregatePerforated PipeCut or Fill Sections
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3 Most Important Items in Road MaintenanceDrainageDrainageDrainage
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Road MaterialsDurability (Hardness)SoundnesspH (acidity/alkalinity)
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Road AggregatesGranularWell Graded (8 15% fines)Free of VegetationAngular / Irregular (Source)CrushedNot rounded
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Basic Road MaintenanceCreate a good hard crust surface with a proper cross slope (crown)
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Basic Road MaintenanceBlading or smoothingGrading or reshapingAdding new materialTransitions
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Basic Road MaintenanceAll work should be done when some moisture is presentNeed moisture for proper compactionAvoids dust
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Blading or SmoothingUse grader or dragMold board tilted forwardLight down pressure30 to 45 degree angle on moldboard10 to 15 degree tilt on front wheels3 to 5 miles an hour
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Grading or ReshapingMoldboard tilted backwardSufficient down pressure to produce cutting action4 passes minimumWindrow & spread each laneCheck cross slopeCompact
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Adding New MaterialScarify existing surfaceSpread new materialBlend old and new material & establish cross slopeCompact
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TransitionsRoad IntersectionsDrivewaysCurvesRailroad CrossingsBridges
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Road IntersectionsGradually eliminate crown 50 to 100 feet from intersectionBe sure shoulders have cross slope at point of intersectionDo not spread aggregate on paved road
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DrivewaysGrade to drivewayGrade low point at ditchlineDo not leave windrow across driveway
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CurvesTransition crown to superelevation (and vice versa) within 100 feet of curves10050250
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Railroad CrossingsGradually eliminate crown on both sidesDo not blade aggregate onto railsBrush off loose aggregate
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BridgesIf bridge has crown, maintain on roadIf not, gradually eliminate crownRoad approaches to bridge may need more frequent attention
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Maintenance FrequencyDepends on:Road TypeDrainageWeatherTraffic VolumesSpecial Events
As Needed!
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The Professional OperatorKnows good techniques & practicesKnows his equipmentNotices and records other problems that need to be taken care of