Western Railroad Discussion > Moffat Tunnel Ventilation Operations

Doesn't anyone know the ventilation procedure for the Moffat Tunnel.  I assumed that the fans would blow against an eastbound train in a similar fashion to the Cascade Tunnel, but it appears that the door is closed after an eastbound and then the exhaust sucked out.  If this is the case would the fans also suck out the air right after a westbound train passes?

Some of this information may be outdated.  For many years, the ventilation fans at East Portal actually blew air from east-to-west, exhausting the tunnel at West Portal (Winter Park).  That worked against the prevailing west wind.  Later, the fans were set up to ventilate the tunnel by exhausting the air at East Portal, but utilzing ventilation ducts rather than the tunnel portal itself to exhaust the tunnel.  That is why there are doors on the tunnel portal at East Portal.  As far as I know, that is the way the tunnel is cleared today.  After an eastbound train exits the tunnel, the East Portal tunnel doors close and the exhaust fans fire up, exhausting the dirty air out of the ducts at East Portal.  As I recall, it takes somewhere around 20-25 minutes to fully ventilate the tunnel, though I suspect that varies depending on the amount of smoke in the tunnel.  I haven't observed westbound trains at the tunnel, so I don't know if the exhaust process starts as soon as the rear of the train fully enters the tunnel at East Portal, or if the startup occurs later or after the train has exited West Portal.  Someone else may be able to answer that.  I do know that there used to be an employee assigned to be at East Portal to monitor the ventilation system, but I believe now that it is remotedly monitored from Omaha.

In the 1970's I was at East Portal and the exhaust from a east bound train started coming out the east portal. There was a lot of diesel smoke and it lasted several minutes probably around 20-25 minutes.  I remember thinking : "that's a hell of a lot of smoke".

As was indicated, the fans at East Portal do indeed suck the exhaust through the tunnel (from west-to-east) and blow the exhaust out at East Portal. For a time, also as said, the fans did blow through the tunnel (from east-to-west). I have heard that the town of Winter Park, and possibly the ski resort, complained a lot to Rio Grande. They did not like the exhaust coming out the west portal multiple times a day. I have never heard if this or the direction of the prevelant winds (or both) is the reason why the venting direction was reversed.

In the past, I have heard the venting begin in a "low" mode with a train in the tunnel (east or west), and then kick it in to high gear after the train clears the tunnel. Haven't listened in a few years up there, so I'm not sure if that's still the case or not.

Good question!

Kevin Morgan
Arvada, CO
ColoradoRailfan.com

Tunnel blows for about 20-30 minutes and it takes coal trains about 15 to go through. Door is down while it blows until the train is a mile away and then it open. Tunnel is blown west. Ever listen to the wind whistle between the cars as Amtrak goes east? That's the blown air being forced by the train

There is an excellent video on YouTube with drone footage of the ventilation plant, and someone who was involved in the modernization of the system in the early 1980s provided a description of the plant in the comment.

Per that comment, in addition to the two 1500 HP fans that suck the exhaust out of the tunnel, there is also a smaller 1250 HP fan that blows into the tunnel to pressurize it against eastbound trains.

Posted from iPhone

I think you can also tell from aboard Amtrak in the tunnel when the exit doors are opened by the pressure change on your ears.