What is the purpose of this loop in a taxiway? This image is of Mariscal Sucre International Airport near Quito, Ecuador.  (Official site / in English)

What is the purpose of the loop in the taxiway plainly visible in this image?


From Google Earth (with the contrast punched up a bit)

Addendum

To respond to the comments to jwzumwalt's answer, I really don't think the hills and mountains to the north of this airport are an operational concern.  See below image:


Source plus my copy-and-paste extras

The airport's elevation is 7900 feet (verified by Skyvector), the first ridge in jwzumwalt's 2nd image is 6.4 miles distant from the north end of the runway and lower in elevation, and the second ridge is 8 miles distant but only 500 feet higher.  Distances verified by Google Maps.

If an aircraft can't comfortably clear a ridge 500 ft above the airfield in eight miles, well then that's a whole other issue. :-)

But, I do like jwzumwalt's answer.  Thanks!
In the US, this is called a "run up area". It is used by small piston powered airplanes to test their engine prior to takeoff.  

The circular design allows several aircraft to full throttle their engines without the prop blast hitting the aircraft behind it. It also allows other aircraft like a business jet, to pass the testing aircraft and takeoff immediately.

Larger aircraft or turbine powered aircraft don't usually test their engines near taxi-ways and other aircraft (or aren't allowed). If they need to test their engines, a special blast "pen" or blast "barrier" is used.



Youtube video of a FedEx engine test.





This Youtube video of a airplane landing shows a ground view of the significance of the hills and mountains off the departure end of 36. 



Why the run-up is at this end - Google Earth 3D