Gravity Hill

OPS Home Page Team Members Cases OPS Central In The Media Friends of OPS Equipment Alabama Folklore Favorite Links Guestbook OOPS - Bloopers OPS Free Forum Join OPS

Munford-Cheaha Mountain

On Saturday January 12, 2008, members of the OPS Team investigated the folklore surrounding Gravity Hill near the Munford-Cheaha Mountain area, gravel road #642. When you first drive up, the road appears to be uphill. The myth is that if you stop your vehicle and place it in neutral that your vehicle will roll up the hill. We tried this numerous times and with each attempt we did appear to roll up the hill. About two-hundred feet from where you start, the road has a crest in it and you are unable to view the other side which lends more to the myth that you truely are traveling uphill. One of our members brought his survey equipment to put the old legend to the test. We found that the entire road as far as the eye can see is an optical illusion. It gives the appearance that you are rolling uphill when you are actually rolling downhill. We measured the entire length of viewable road and further on past the crest in the road. Every measurment showed us that we were indeed traveling downhill. As one member said, it is a hill on a hill, that's why you have the crest. This folklore is officially busted, debunked and OPS tested. Below is actual measurments from the road on the day we visited from the survey equipment.


Our Equipment:
    Dietzgen Model 6300 Transit
    Surveyor’s tripod
    Surveyor’s Grade Rod
   100 foot measuring tape
Feet and inches of drop/slope
  0 Ft.       5-1
10            5-3 3/4
20            5-6 1/4
30            5-9 1/4
40            6
50            6-3
60            6-5 3/4
70            6-8
80            6-10 1/4
90       7-1/4
100          7-2 1/4
110          7-4
120          7-5 1/4
130          7-6 1/4
140      7-7 1/4
150          7-8
160          7-8 1/4
170          7-10
180          7-11
190          8-1
200          8-3 1/2
210          8-6 1/2
220          8-10 1/4
230          9-3
For a total drop of 4.17 feet in the 230 feet.

The percentage of grade from 0-200 feet is 1.6%.  That is a about a 1.6 foot drop every 100 feet.  This is considered a very slight grade.  At about 200 feet the grade increases.  This gives the illusion of a crest.  The total grade from 0-230 feet is 1.8%