Some railroads, CSX comes to mind locally, have 60mph speed limits for intermodal trains vs 50 for general freights. Is the differential (10mph) based on market demands for intermodal, equipment differences (higher speeds allowed for intermodal equipment) or economics (cheaper to run at 50mph vs 60mph)?
I also believe the apple train (Q090/Q091) from UP to New York runs at 60mph as do the auto rack trains.
Thanks for comments,
Ed
I’m guessing here, but I’d hazard that the relatively consistent makeup of intermodals and the “salad shooter” make train dynamics such that the higher speed is possible. With a manifest it’s a crapshoot.
I can’t speak towards what CSX does, but for the UP it isn’t necessarily train type per se. It’s specific restrictions on equipment or tons per operative brake restrictions, etc that may limit train speed.
For example the salad shooter (your apple train) has reefers that are allowed a top speed of 70mph. When the train is loaded, tons per operative brake can cut that down to 50mph. So the only time it can do 70 is when it is empty. Add in fuel conversation throttle/speed restrictions and soon it will only be able to do 70 down hill. With a tail wind.
Jeff
Here is a link to a train pacing video I made @ Daggett CA
http://www.youtube.com/watch?v=h4TJ4yBNYZA
I believe that the max speed for freight trains is 70 MPH & in most corridors for passenger trains 79MPH
[:)]
Another factor is that some trains (e.g. the “salad shooter” and the UPS intermodal trains) have a specific time that they MUST be at their destiantion by or there is a severe penalty that the railroads must pay. This is built into the schedule and these trains run at maximum allowable speeds with NOTHING getting their wy.
Any of you who drive I-40 between Barstow and Albuquerque will have several opportunities to be parallel with the BNSF Transcon and you will usually see their intermodal trains running beside you. I have paced several doing 70 MPH. And there may be another one a short distance behind doing the same thing. At peak times there may be 100 trains a day on the Transcon.
As mentioned above, the equipment is consistent in configuration and subject to inspection with hot box - dragging equipment detectors every 25 miles.
Several factors are involved, but the main reason the intermodal trains get the higher speed is the commercial requirements that drive the train schedules. They are trying for cut-off and placement times that the market wants.
Slower trains burn less fuel, so 50 mph makes sense for merchandise trains - although it is almost a moot point these days with the very low HP/ton used on most trains. The are lucky to make 50 mph on the downgrade.
Equipment constraints also play a part. All intermodal equipment is good for 60+ mph without any dynamic issues. Some freight cars, particularly empty ones have speed limits based on dynamics. On NS, for example, empty bulkhead flats have a 45 mph speed limit, if I remember right. Other short, empty equipment can get in trouble at speeds approaching 60 mph. Conrail had a rather nasty derailment in the early 90s due to moving empty mill gons back to Burns Harbor on the head end of an intermodal train. Great for car utilization, but the cars hunted badly and a one finally derailed just east of Cleveland.
Overall, though, faster is cheaper as car ownership costs are bigger than just about everything else. There may come a day when faster train speeds will help reduce car trip time (if you can get a train into a terminal a couple hours earlier, the some of the cars will make a faster connection to the their next outboun
Don:
Did Conrail push intermodals to 70mph? I seem to recall seeing pigs flying thru Porter (CP482) one night at dusk that made a lasting impression on me.
Ed