CLIMATIC FACTORS CONTROLLING ROADSIDE DESIGN AND DEVELOPMENT
STUDIES HAVE BEEN DIRECTED PRINCIPALLY TOWARD FINDING OUT THE EFFECT OF TREE PLANTINGS FOR SHELTERING CROPLAND AGAINST DRYING WINDS AND FOR PROTECTING HABITATIONS AGAINST THE HEAT OF SUMMER AND THE RIGORS OF WINTER. MEASUREMENTS HAVE ALSO BEEN MADE OF THE EFFECTS OF COMPLETE DENUDATION OF THE NATURAL VEGETATION COVER IN COMPARISON WITH ADJACENT AREAS IN FOREST AND GRASS. RESEARCH FINDINGS IN THESE STUDIES HAVE MANY APPLICATIONS TO ROADSIDE DEVELOPMENT PROBLEMS. LAND AREAS UNDER TREE PROTECTION DO NOT SHOW THE EXTREME VARIATIONS IN SOIL TEMPERATURES CHARACTERISTIC OF BARE SOIL. DENSE BRUSH AND LOW TREES RETARD SNOWDRIFT FORMATION. WIND VELOCITIES OVER BARE SOIL MAY BE FIFTEEN TIMES AS GREAT AS OVER ADJACENT FORESTED AREAS AND EIGHT TIMES AS GREAT AS OVER GRASS LAND. SUCH VELOCITIES DRY OUT SURFACE SOILS RAPIDLY. DAILY RANGE OF SURFACE SOIL TEMPERATURES MAY BE 33.5 F AS COMPARED WITH A DAILY VARIATION OF ONLY 10.9 UNDER HEAVY VEGETATION. MULCHES AND PLANTING DURING PROPER SEASONS ARE NECESSARY IN ESTABLISHING VEGETATION ON BARE SOILS SUCH AS THOSE ON HIGHWAY SLOPES. IN ADDITION TO PROTECTION AGAINST WIND, MULCHES OR VEGETATIVE COVER ARE NEEDED TO PREVENT RAPID FREEZING AND THAWING OF SOILS ON CUT AND FILL SLOPE. SLOPES FACING TO THE SOUTH OR WEST PARTICULARLY NEED INSULATING PROTECTION AGAINST THE SUN. SMOOTH SURFACES ON CUTS AND FILLS ARE PARTICULARLY CONDUCIVE TO HARMFUL FROST ACTION CAUSING SLUMPING AND SLIDING OF SLOPE SOILS. SUCH SOIL MOVEMENT MAKES ESTABLISHMENT OF VEGETATION VERY DIFFICULT. ALL THESE OBSERVATIONS POINT TO THE NEED OF ESTABLISHING PROTECTIVE VEGETATION ON ROAD SLOPES AS SOON AS POSSIBLE AFTER GRADING. /AUTHOR/
- Record URL:
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Supplemental Notes:
- pp 9-19, 12 PHOT. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.
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Authors:
- Hursh, C R
- Publication Date: 1949
Media Info
- Media Type: Digital/other
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Serial:
- Highway Research Board Roadside Development Committee Reports
- Publisher: Highway Research Board
Subject/Index Terms
- TRT Terms: Climate; Erosion control; Plants; Roadside; Screenings; Snowdrifts; Temperature gradients; Trees; Wind
- Old TRIS Terms: Plant cover
- Subject Areas: Design; Environment; Highways;
Filing Info
- Accession Number: 00205005
- Record Type: Publication
- Report/Paper Numbers: pp 1-8
- Files: TRIS, TRB
- Created Date: Dec 6 1971 12:00AM