In order to be able to simulate 100K miles in service in a timely and cost effective manner, it is necessary to use accelerated vibration testing. This results in a time compression by increasing the severity of the input vibration. >br /> Several publications give a range consistent with the above .145-.252 Grms values. Assuming the .145 Grms profile represents real world inputs, we can then use the ASTM Level I input to compress the time required to reach 100K miles. In this case the .145 Grms input occurred over 24 hours, which at 60 mph would equate to 1440 miles traveled. We can compress this by a factor of about 25 by running the ASTM .73 Grms input. In other words, it takes about 1 hour of shaker input to simulate 1440 miles traveled.