CSIR - Central Research Institute

Shoulders for Rural

U.K.Guruvittal Chief Scientist, CRRI Road Shoulders  Roadway portion bordering travelled way for accommodating stopped vehicles and for lateral support of base and surface courses (FHWA, USA)  Unpaved edges of the roadway, between the edge of and the shoulder break point (NRIDA)  Space for pedestrians, slow moving , stops,

installation of road signs, or halting U.K.Guruvittal  Helps to drain out surface run-off, improves sight distance in hill roads (cut sections)  Materials – Earth , Local / marginal material, , paver blocks 2 Road Shoulders

 MORD Specifications, Section 407 – Construction (Earth/ granular material)  MORD Specifications, Section 1903 – Maintenance of Earthen Shoulders

U.K.Guruvittal 3 Shoulder Geometrics

 Minimum shoulder width – 0.6 m if ADT is less than 40, otherwise 1.2 m (www.pmgsy.nic.in/op48.htm)  Hard shoulders of 1 m width on either side if soft soil is used for embankments (PMGSY Operations Manual)  Shoulder width for rural roads – 1.5 m to 1.875 m

(IRC SP:20 ) U.K.Guruvittal  Camber – Earthen shoulder 4%, shoulder 4 to 6.25%, Turfed shoulder 8.33% (www.pmgsy.nic.in/op48.htm)

100 ADT – 19,400 ESAL, Corresponds to T1 Category 10,000 to 30000 ESAL for design life of 10 Years

4 Materials / Construction  IRC SP:20 – Density criteria (soil) similar to subgrade 3 (16.5 kN/m ). Ambiguity in MORD Specifications (Selected earth where specified shall conform to requirements of section 300 and shall be less than 10 percent)  LL and PI limits – PI should be less than 10  Shoulder construction – Simultaneously with adjoining pavement layer, matching its thickness  Earth and granular shoulder to be compacted to at

least 100% of its standard proctor density U.K.Guruvittal  Box cutting not allowed for shoulder construction  Shoulder Problems – Due to Shortcomings and Neglect during construction or maintenance 5 Materials / Construction

U.K.Guruvittal 6 Shoulder Problems

 Erosion, Rutting, Camber irregularities, Edge drop off  Shoulders can become hazard spot, affect road safety  Hills – Shoulders affect stability of valley side slope

U.K.Guruvittal 7 Maintenance

 Earthen/ Gravel shoulders to be maintained in a manner similar to earth / gravel roads  Edge drop – Erosion from run-off and traffic abrasion, acute problem in case of concrete pavements  Reverse camber – Avoided by proper blading  Rain cuts to be filled and compacted – Smaller rollers  Repairs to be done with same quality of material used for shoulder construction U.K.Guruvittal  Turfing can be a good solution to solve many of shoulder problems 8 Smaller Rollers

9 Solutions  Improved specifications , Proper construction practices, Excluding highly plastic soil usage  Periodicity of inspection and maintenance operations should be higher than black top or concrete roads (Dressing of berms – Once a year (Routine Maintenance, IRC SP:20)  Local materials, soft stones, Cell filled concrete, Quarry/ Mining waste, ICBP, Geosynthetic, Fal-G  Industrial waste (Fly ash, slag, foundry sand, quarry waste, etc) + 3 to 5% cement can be another option (0.6 m wide, 0.15 m thick, 7 days compressive strength of 1.7 MPa) U.K.Guruvittal  Technology demonstration projects for better shoulders 10 11