Let 'r' represent the radius of the circular 'end caps' of the track.  Let 'PI' represent the constant which is approximately equal to 3.14.  Let 'P' represent the perimeter and the perimeter is equal to (double the long track plus the circumference of a circle that has been split into two pieces, one at one end of the track and the other at the 'other end'!):

P=2(150)+(2*PI*r)