Introduction:-

Now a days traffic need extra space to flow smoothly, the interchange is usually used to change the direction of traffic route, usually interchange shared by two or more roads at the same zone, the interchange is a connection between main road line with one or more grade separations on different level (ramps) that provide the access for traffic for changing its direction. Interchange usually used on freeways and expressways where the access point is important such as change direction, turning traffic, etc. There is some cases which is the crossing, changing route and turning traffic can not accommodated by normal grade separation with out ramps.

Selection Types of Interchange:-

1- T-Crossing: In this case when one traffic route ends at the interchange with another route, the route which is ends with main route it make a T-section, interchange may require to access the traffic and connect both route with full access-able movement, for this cases usually (Trumpet and three leg directional interchange) can be used as shown in (Figure 1,6).

2- Full Crossing: In this case when two traffic route intersect with each other, for this case usually (cloverleaf,diamond and Four Leg Interchange) can be used as shown in (Figure 2,3,4,5).

Types of Interchange:-

1-Trumpet Interchange:-

Fig-1: Trumpet Interchange

2-Diamond Interchange:-

Fig-2: Diamond Interchange

3-Full Cloverleaf Interchange:-

Fig-3: Full Cloverleaf Interchange

4-Partial Cloverleaf Interchange:-

Fig-4: Partial Cloverleaf Interchange

5-All Directional Four Leg Interchange:-

Fig-5: Four Leg Interchange

6-Three Leg Interchange:-

Fig-6: Three leg Interchange

7-Single Point Urban Interchange:-

Fig-7: Single Point Urban Interchange

The speed on ramps should be determined and designed, the shape of ramps, length of ramp, vertical curve of ramp, design speed of mainline and some other condition can be considering for design the ramps, (Table-1) provide some information about design speed on ramps with three speed category, the numbers is based on design speed on mainline.

Table-1: Design speed on ramps


Reference:-

1- A Policy on Geometric Design of Highways and Streets, American Association of State Highway and Transportation Officials, Washington, D.C., 2004, p. 744.

2-Garbor, N.J., Hoel, L.A.,2009. Traffic and Highway Engineering. 4th ed. USA: Cingage Learning,PP.266.

3- Location and Design Manual, Vol. 1, Roadway Design, Ohio Department of Transportation.


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WRITER PROFILE:-

BALEN ZRAR ABDULSAMAD

BSc- Geotechnical Engineering\Koya University

MSc- Infrastructure Engineering\ Szechenyi Istvan University


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