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Raised C/E to Thumpet I/C

Raised C/E to Thumpet I/C by Pager

Trumpet interchanges have been used where one highway terminates at another highway. These involve at least one loop ramp connecting traffic either entering or leaving the terminating expressway with the far lanes of the continuous highway.

Trumpet interchanges are named as such due to their resemblance to trumpets. The bell of a trumpet can be seen where the terminating highway begins to interchange with the continuous highway, and the resemblance to the tubing is seen along the connecting loop ramps.

Occasionally a third ramp can be routed around the loop instead of one of the non-looping ramps. A vehicle will therefore diverge from the continuous highway, cross it, turn 270 degrees left and cross the continuous highway again (or vice versa if the ramp is for traffic turning off the continuous highway). An example of this is where the Kingsway Tunnel terminates on the A59 in Liverpool, England - because of the steep gradient of the tunnel approach there was insufficient space for a simple left-turning ramp.

These interchanges are useful for highways as well as toll roads, as they concentrate all entering and exiting traffic into a single stretch of roadway, where toll booths can be installed once to handle all traffic. A double-trumpet interchange version can be found where a toll road meets another toll road or a free highway. They are also useful when most traffic on the terminating highway is going the same direction. The turn that isn't used often would get the slower loop ramp. Such designs are most often found in the United States, Japan and Italy.

There is a rarely built four-leg interchange type based on the trumpet interchange, of which there are two examples each in the United States and Singapore, one each in Sweden and Norway. One of the earliest examples of this interchange type was constructed in the 1950s and existed until 2005 at the junction between Interstate 94 and US 24 in Taylor, Michigan

Info provided by: https://en.wikipedia.org/wiki/Interchange_%28road%29