We found it ! Anyone who has seen or heard of the service tunnel to the 25 C is familiar with the enigmatic ventilation shaft bored through the solid rock. The lower end of the ventilation shaft is located almost at the point the service tunnel meets the 25C. We also find the top end.
Here are a few URLs showing the exterior of the service tunnel:
Click Here
Click Here
Click Here
Click Here
And here are a few URLs showing the view of the shaft from inside the 25 C – looking vertically upward:
Click Here
Click Here
John peers into the deep hole protected by the extra tall side wall – studded by embedded shards of glass, not a serious deterrent to a determined railfan !