Question

briefly define plan and profile of a roadway

Answer 1

Plan of roadway

The plan shows top view of roadway.The length,width,purpose,which city/district/state etc can be known from plan of roadway.Plans shows different components ie the cross section of roadway can easily be identified from plan.

Components of roadway include:

1.Subgrade:it is the foundation of a road.Based on land profile the soil should be added or taken away for construction purpose.It bears and transfer load.

2.Sub base:upper and lower sub base are there.If rigid pavement is upper course of this base is provided and for flexible pavement upper and lower course are provided.7.5-15cm thick.Prevent capillary action.Materials are sand,gravel etc strong and easily available and are also cheap.Load bearing and transfer.

3.Road base: Support bearing course.Bear load and transfer.Above sub base.It support wearing course and reduce wearing.

4.Surfacing:it includes binders and weathering course eg:bitumen,concrete,tiles etc

Profile of roadway

Profile means cutting a road through centerline vertically.Crest,sag,grade lines etc can be seen or marked in road profile diagram.Drainage is designed based on the profile of road.Flat road with steep curve have poor drainage than that of roads in steep hills.The complete profile of road such as vertical and horizontal profile can be known and also sag and crest vertical curves,zig zags,hair pin roads etc can also be identified.Different roads have different profile.