Rotary intersection and its elements, shapes of rotary island, guidelines for selecting a rotary intersection, advantages and disadvantages.

1. ROTARY INTERSECTION
BY
RAVINDRA C

2. It is a specialised form of at grate intersection laid out for
movement of traffic in one direction round a central island.

3. ROTARY ELEMENTS :
 Diverging : The dividing of a single stream of traffic into separate
streams
 Merging : The converging of separate streams of traffic into a
signal stream
 Weaving : The combined movement of merging and diverging of
traffic streams moving in the same general direction
 Weaving length : The length of a section of a rotary in which
weaving occurs.

5. 
SHAPES OF
ROTARY ISLAND

6. Guidelines For Selecting A Rotary Type Intersection :
1. Rotaries are most apt where volumes entering from different
intersection legs are approximately equal
2. A rotary is most appropriate when the proportion of turning
traffic is very high
3. Maximum 3000 veh per hour is max practical capacity of
high type rotaries
4. A rotary is a good choice when there are more than four
approaches to the junction
5. When the approach radius width are restricted rotaries are
more desirable
6. Rotaries are not suitable for traffic carrying very low volume

7. ROTARY
INTERSECTIONS

8. Advantages of Rotary intersection :
1. Ordered and regimented traffic flow
2. Frequent stopping and starting are avoided
3. Traffic proceeds simultaneously and continuously
4. Weaving movement replace the usual angular movement
5. Turns can be made easy
6. Self governing
Disadvantages :
1. Difficult for right taking
2. Requires more land
3. Travel troublesome
4. Requires many warning and directional signs for safety
5. Difficult for pedestrians
6. Difficult when intersection angle is too cute.