Light Reflecting Characteristic

  3. Light Reflecting Characteristic

  • Visibility over the pavement depends upon its color & light characteristic 

  • The glow caused by reflection of headlights is high on wet pavement surface then dry pavement surface

  • Light coloured pavement provide good visibility at night but produces more glow in sunlight on the other side dark color pavement offer good visibility in day and bad visibility at night


It is the slope provided to the road surface in the transverse direction to drain of the rainwater from the road surface to avoid the following

  • Strippping of bitumen from the aggregates in the presence of water

  • Swelling & leaving of subgrades in case water steep upto it

  • The slipping of vehicles over the wet pavement

  • Glare over the wet pavement surface

  • On Straight road it is provided by raising the edge center of the carriage with respect to the edge forming the crown on the highest point along the central line

  • At horizontal curve with the superelevation the surface drainage is provided by raising the outeredge.

It is represented in any of the following ways

As a % for eg.cross section slope of 5% tanθ=5/100

  • NOTE:

  1. The cross slope of shoulder should be more the that of pavement  so as to avoid accumulation of water at function of two

  2. Cross slope of the shoulder should be more 0.3% than cross slope of adjoining pavement having min value of 3% and max value of 5%

  3. The cross slope on expressway for carriageways & paved surface shoulder & edge strip with bitumen surface is 2.5%  with rainfall exceeding 1000mm &2 % and place having rainfall less than 1000 mm

  4. If two steep slope is provided it result in  

  • Toppling of slow running & overloaded vehicle

  • Tendency of most of the vehicles to travel along the centerline

  • Uncomfortable side thrust & drag along the vehicle