Crowfield Road, Centre County - Center for Dirt and Gravel Road ...

crowfieldroadStudy objective& placement detailscrowfieldroadAggregate details & study informationStudy Objective:To evaluate the performance of three differentaggregate gradations utilizing two differentplacement techniques. A secondary objectiveof the project will be time and cost analysis ofthe two placement techniques.Placement Details:Tailgating: A traditional method of aggregateplacement, tailgating involves dumping theaggregate out of the truck and onto theroadway. The aggregate is then spread andshaped using a road grader. Compaction wasprovided by traveling over the graded materialwith aggregate truckstailgatingPaver: A newer method of placing surfaceaggregate, trucks unload aggregate into amachine instead of directly on the road. Thepaving machine places a uniform 8” lift ofaggregate across the road. Compaction isprovided using a vibratory roller.placement with paverAggregate Details:2A: PENNDOT’s 2A specification. This specification is designed as an underdrainage or basematerial for paved roads, but is a commonly used surface aggregate. The 2A specification has abroad range of acceptable sizes, and the fine material may come from a variety of sources.DSA: The Dirt and Gravel Road Program’s Driving Surface Aggregate is specifically designed formaximum compaction for use as a driving surface. The DSA specification is very tight and containsa larger percentage of very fine material that fills the gaps between the larger stones to create ahighly compacted surface. The fine material in DSA is composed entirely of crushed parent rock.Clay Added DSA: While the size specification closely resembles the DSA described above, fine claymaterial has been added to this aggregate as substitute for crushed parent rock.Study Information: Study started Fall 2002Time/Cost Analysis:In order to determine long-term maintenance needs and costs, all project expenses were recordedseparately for each of the six road segments. Initial placement costs, aggregate durability, andmaintenance requirements over a period of at least three years will be used to compare theoverall cost-effectiveness of the six road segments.Cross-Sections:Road cross-sections are being usedto monitor the long-term durability ofthe road. Each of the six sections ofroad have three cross-sections thatare surveyed regularly. By looking athow the various cross-sectionschange in elevation and shape overtime, we can compare the durabilityand effectiveness of the six sectionsof aggregate. By looking at threecross- sections on each road segment,we can also calculate theamount of road material that hasmoved off of the road.Elevation (ft)91.0090.5090.0089.5089.0088.5088.000 5 10 15 20 25Distance (ft)BeforeGradedAfter1 MonthMarch 2003May 2003July 2003

crowfieldroadWhat to look forWhile comparing the sections of CrowfieldRoad, be sure to consider the followingfactors:APPEARANCE: The shape, uniformity, andoverall appearance of each road segment arevery important. Roads that hold their crownwill retain less water and are less likely tobreak apart. Look to see if loose stones arepiled in the middle of the wheel tracks and tothe sides of the road.COMPACTION: Compaction of aggregatematerial is critical for a road to hold itselftogether. Some sections have large loosestone on the surface. These loose stones willgrind into the surface under the abrasiveforce of traffic to produce more loose stonesand dust. A hard compacted surface withminimal loose stone on top will last longer.RUNOFF: Be sure to look at the ditches andoutlets along the road. Is there evidence ofroad material being washed from the surface?In some cases, outlet ditches contain asignificant amount of material that has beenwashed off of the road surface. This materialbecomes sediment that can pollute nearbystreams.DEPTH: Although depth of aggregate materialis hard to visibly identify, it is a crucial part ofthis study. The tailgated road segments(1,2,3) vary from 2-6 inches in depth. Theroad segments placed with the paver (4,5,6)are approximately 6 inches deep on average.Despite a higher initial cost, the deeperplacement of material with the paver may bemore cost effective over time.crowfield road:site location & directionsCrowfield Road is located just off US Rte 32211 miles south of State College in SouthernCentre County. Turn West off US 322 just asit turns from two lanes to four lanes going upSeven Mountains. The project site beginsabout ½ mile from US 322.StateCollegeCrowfieldRoadCentreCountyFunding for the project provided by theCenter for Dirt and Gravel Road Studiesand the Bureau of ForestryPlease contact the center with any questions:toll free: 1-866-668-6683e-mail: dirtandgravel@psu.eduFor more information visit:www.dirtandgravelroads.orgaggregatestudycrowfieldroadKeyTailgatedSections1: Clay AddedVariation to DSA2: 2A3: DSAPavedSections4: Clay AddedVariation to DSA5: 2A6: DSALook forcorrespondingnumbered signson siteThe CrowfieldRoadAggregate Studyis a collaborationof Penn StateUniversity’sCenter for Dirtand Gravel RoadStudies and PABureau ofForestry’sRothrock StateForest.