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Forest Road Location and Geometric Design NERCoFE 2015 Workshop, - - PowerPoint PPT Presentation
Forest Road Location and Geometric Design NERCoFE 2015 Workshop, - - PowerPoint PPT Presentation
Forest Road Location and Geometric Design NERCoFE 2015 Workshop, March 9-10, 2015 Wells Conference Center, University of Maine at Orono Robert A Douglas, BASc, PhD, PEng Softree Technical Systems Inc. Outline Road location / geometric
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ROAD ROAD LOCAT LOCATION ION / / GEO GEOMET METRI RIC C DESIGN DESIGN
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Road location / geometric design
Road Location:
Finding a “corridor” – strip of land ¼ to ½ mile wide, from origin to destination Deciding between this valley or that, this ridge
- r that
Geometric design
Specific alignment – the centerline’s grades, curves
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ROAD ROAD LOCAT LOCATION ION INPUT INPUTS
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Road location inputs
Purpose of the road
Harvesting system
Terrain Road-building materials Construction expertise Construction equipment Vehicles
Roads are built for vehicles!
garagejoournal.com
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ROAD ROAD LOCAT LOCATION ION STRA STRATEG TEGIE IES
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Road location strategies
Stay on ridges Stay in valleys Run across the drainage pattern Run along the shoulders of hills Ignore the topography
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ROAD ROAD LOCAT LOCATION ION PROCE PROCESS SS
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Road location process
Office study Field reconnaissance Route survey Location survey Construction surveys As-built survey
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A paradox
Decisions on route Cost to company BIG small Small – just the locator’s salary LARGE – construction of change in alignment
Road location process proceeds
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GEO GEOMET METRI RIC C DESIGN DESIGN
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Geometric design - gradients
7% gradient 8 HP/ton (e.g. 400 HP, 50 tons)
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Geometric design – horizontal curves
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- AASHTO. 2001. Guidelines
for geometric design of very low-volume local roads (ADT < 400). Washington, D.C.: American Association of State Highway and Transportation Officials (AASHTO). 72 pp.
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garagejoournal.com
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Douglas, R.A. 2006. Forest roads, resource access roads: delivery – the transportation of raw natural resource products from roadside to mill. Windsor, Ontario: R A Douglas. 202 pp.
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Minimum radius for roll-over criterion, based on maximum lateral acceleration of 0.15G
Design speed (km/hr) Minimum radius (m)† Design speed (mi/hr) Minimum radius (ft)‡
30 45 20 180 40 85 25 280 50 130 30 400 60 190 35 550 70 255 45 900 80 335 50 1110 90 425 55 1350 100 525 60 1600
† rounded to nearest 5 m ‡ rounded to nearest 10 ft
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Geometric design – vertical curves K = L / A
ft / % or m / %
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WATER WATERCROSSI CROSSING NGS
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Watercrossings
Major sediment sources – we must do them well!
Hydraulic considerations
Road location issues
Approaches: horizontal and vertical alignments Span requirements
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Keller, G., and Sherar, J.
- 2003. Low-volume roads
engineering – best management practices field
- guide. Plumas National
Forest, California: USDA Forest Service. 158 pp.
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ROAD ROAD LOCAT LOCATION ION IN IN NE NE FORE FOREST ST OPE OPERATION RATIONS
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Road location in NE forest
- perations
Most of the roads needed are complete Rare to locate a road from scratch - rare to start with a “clean slate” Rare to be locating a high-class road – new roads usually short accesses to cut blocks
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May need to improve an existing road
Straighten a dangerous alignment Better radius curve Change an intersection into a curve
More a matter of geometric design
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Resort to computerized solutions Need to know the topography LiDAR
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