Thursday, February 13, 2014

Road Margins - Highway Engineering

Road margins are the various cross sectional elements of the road except the carriageway or pavement width. 
Various road margins are shoulders, foot-paths, cycle-tracks, frontage paths, driveways, lay byes, side slopes and guide rails. I will discuss each, one by one.

  • Shoulders: Shoulders are the parts of the formation width except carriage ways. In other words, shoulder is the part of the pavement which is non-surfaced. 
They are used by the vehicular traffic as the emergency lanes or sometimes as the service lanes for the repairing of the non-expected problems. IRC recommends a minimum value 2.5 m for the shoulders for two lane rural roads. A width of 4.6 m is recommended so that a truck can be accommodated without interfering with the adjacent lane. 
  • Footpaths: Foot paths or pedestrian paths are the smoothly paved paths used by the pedestrians to walk parallel to the pavements. Footpaths are smoothly surfaced in order to attract the pedestrians to walk over them. Footpaths are necessary where the pedestrian traffic is considerable.
  • Cycle-tracks: Cycle tracks are provided to carry the cyclists. They are generally provided in the urban roads where the design speed is very high and it becomes necessary to separate the high speed traffic from the low speed traffic. Minimum of 2 m width is recommended for single lane and 1 m is added for constructing the extra lanes of the cycle tracks.
  • Frontage Paths: They are provided in front of the commercial buildings where it becomes a necessity. In urban areas they are provided with the dividers to separate from the vehicular lanes.
  • Drive-ways: Drive ways are provided to reach the buildings like fuel pumps or service centers. Drive ways should have a less width as much as possible because they are hindrance to the pedestrian traffic travelling along the foot-paths.
  • Lay Byes: Lay Byes are the paved areas provided at some places on the sides of the lanes for providing a stoppage for the vehicles. 
  • Parking Lanes: They are provided for parking the vehicular traffic generally needed in the market centers or the urban areas. Parallel parking is recommended in order to avoid the hindrance to the traffic and a minimum of 3 m parking lane is recommended.
  • Side Slopes: A proper, flatter/gentle side slopes are necessary in case of filling or cutting for the stability of the pavements. If possible they must be provided with the landscaping so making them a pleasant and aesthetic appearance and making more stable.

  • Guide Rails: Guide rails are provided on the roads on filling generally on the hills, on the outer edges, for the psychological as well as physical protection to the driver. 

Sand Cone Method to Determine Density - A solved Example

Hi, This problem deals with the Sand Cone Test used to determine the density of the compacted soil. Problem: A sand cone density test w...