The following technical terms should be clearly understood before making detailed study of a road construction.
1. RIGHT OF WAY-
The area of land acquired for construction and future development of a road symmetrical about the central alignment is called right of way. The width of these acquired land is known as land width and it depends upon the importance of the road and possible future development.
2. FORMATION WIDTH-
The top width of the highway embankment or the bottom width of highway cutting excluding the side drains is called formation width or road way. The formation width is the sum of widths of pavements of carriage way including the separators and width of the shoulders on either side of the carriage way.
3. CARRIAGE WAY-
The portion of the road surface which is used for vehicular traffic is known as carriage way or pavement. The width of carriage way depends upon the width and number of lanes. For single lane roads the width of pavement is generally kept 3.75 m.
4. CROWN-
The highest point on the road surface is called crown..
5. CAMBER OR CROSS SLOPE-
The rise of the center of the carriage wway about its edges along the straight portion of a road is called camber or cross slope. The transverse slope of the pavement is provided for the drainage of rainwater. The amount of camber for the roads is decided according to the road surface and the amount of rainfall.
6. SEPARATOR OR DIVIDER-
The narrow continuous structure provided for dividing the two directions of the traffic flow is known as separator or divider.
7. SHOULDERS-
The portion of the roadway between the outer edges of the carriage way and edge of the top surface of the embankment or inner edge of the side drains in cuttings of the roads are called shoulders. The shoulders are generally in level with road surface having a slope towards drain side. The shoulders and foot path prevent the edge of the road from wear and tear. The minimum shoulder width recommended by IRC is 2.5 m.
8. KERBS-
The boundaries between the pavement and shoulder of foot path are known as kerbs. These are also provided between the pavement and the traffic separator or divider. It is desirable to provide kerbs on urban roads.
9. SIDE SLOPES-
The slopes of the sides of earth work of embankment and cutting to ensure their stability are called side slopes. The embankment are generally given a side slope of 1:1.5.
10. BERMS-
The width of the land left in between the toes of the embankment and the inner edges of the borrow pits is called berms.
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