Terrain Classification & Width of Formation | Transportation Engineering - Civil Engineering (CE) PDF Download

Right of way 
Right of way (ROW) or land width is the width of land acquired for the road, along its alignment. It should be adequate to accommodate all the cross-sectional elements of the highway and may reasonably provide for future development. To prevent ribbon development along highways, control lines and building lines may be provided. Control line is a line which represents the nearest limits of future uncontrolled building activity in relation to a road. Building line represents a line on either side of the road, between which and the road no building activity is permitted at all. The right of way width is governed by:

Terrain classification
The topography of the land traversed has an influence on the horizontal and vertical alignment of a highway. The terrain classifications pertain to the general character of a specific route corridor. For design purposes, variations in topography are categorized by terrain, utilizing the definitions in AASHTO's A Policy on Geometric Design of Highways and Streets :
Level Terrain - That condition where highway sight distances, as governed by both horizontal and vertical restrictions, are generally long or could be made to be so without construction difficulty or major expenses.

Rolling Terrain - That condition where the natural slopes consistently rise above and fall below the road or street grade and where occasional steep slopes offer some restriction to normal horizontal and vertical roadway alignment.

Mountainous Terrain - That condition where longitudinal and transverse changes in the elevation of the ground with respect to the road or street are abrupt and where benching and side hill excavation are frequently required to obtain acceptable horizontal and vertical alignment.

Design Speed:
It is the maximum safe speed that can be maintained over a specified section of highway when conditions are so favorable that the design features of the highway govern. The factor which affect the choice of a design speed are:
a)Class of road and terrain.
b)Curvature and its magnitude.
c)Condition of road surface.
d)Sight distance.
e)Nature, intensity and type of traffic.
f)Type and nature of road surface.

Right of Way (ROW) or land width is the width of land acquired for the road, along its alignment. It should be adequate to accommodate all the cross-sectional elements of the highway and may reasonably provide for future development. To prevent ribbon development along highways, control lines and building lines may be provided. Control line is a line which represents the nearest limits of future uncontrolled building activity in relation to a road. Building line represents a line on either side of the road; between which and the road no building activity is permitted at all. The right of way width is governed by: Width of formation: It depends on the category of the highway and width of roadway and road margins.
Height of embankment or depth of cutting: It is governed by the topography and the vertical alignment. Side slopes of embankment or cutting: It depends on the height of the slope, soil type etc. Drainage system and their size which depends on rainfall, topography etc.

Sight distance considerations: On curves etc. there is restriction to the visibility on the inner side of the curve due to the presence of some obstructions like building structures etc. Reserve land for future widening: Some land has to be acquired in advance anticipating future developments like widening of the road.



Width of formation
It depends on the category of the highway and width of roadway and road margins. Height of embankment or depth of cutting: It is governed by the topography and the vertical alignment. Side slopes of embankment or cutting: It depends on the height of the slope, soil type etc. Drainage system and their size which depends on rainfall, topography etc.Sight distance considerations : On curves etc. there is restriction to the visibility on the inner side of the curve due to the presence of some obstructions like building structures etc.Reserve land for future widening: Some land has to be acquired in advance anticipating future develop- ments like widening of the road.

The alignment is the route of the road, defined as a series of horizontal tangents and curves.

The profile is the vertical aspect of the road, including crest and sag curves, and the straight grade lines connecting them.

The cross section shows the position and number of vehicle and bicycle lanes and sidewalks, along with their cross slope or banking. Cross sections also show drainage features, pavement structure and other items outside the category of geometric design .