Norfolk Southerns's new Nemo Tunnel # 24 - Query...

Last night I was watching a Pentrex DVD called "The Rathole". Towards the end of the main feature, there were some run-by shots of NS Triple Crown RoadRailers passing through the (not so newer) Tunnel # 24 at Nemo. I am interested to know what the smaller vertical openings are for on either side of the main tunnel bore. These openings appear to run the entire length of the tunnel itself and are visible at both Portals. Are these side openings there for ROW maintenance purposes or were they intended to be part of some fumes extraction equipment? This seems unlikely given that the tunnel itself is not a long one so I am perplexed somewhat.

Cheers.

They are part of the exhaust extraction and they do not follow the entire length of the tunnel but taper inward to the main bore as you move into the portal. Southern Railway was very forward thinking and put some design considerations in the tunnel that were intended to future-proof the structure, that includes the extraction vents and provisions to add overhead catenary if needed.




you can see the tapering pretty well in this snip.