Hi-Rail fuel efficiency

[CLamb]

Is there a significant difference in fuel efficiency of hi-rail vehicles between rail running and road running?

[litz]

I would imagine on the road, the fuel efficiency takes a hit compared to a non-hi-rail of the same make/model, simply due to the weight of the running gear. It's NOT light.

On rail, because you're driving at slower speeds than on road, there's going to be a different efficiency hit there as well.

[FarmallBob]

The short answer is "it depends". If you look at instantaneous fuel efficiency - the efficiency of a hirailer when its actually in motion - it is likely somewhat higher on rails than on the road. This on due to the reduced rolling friction of steel wheels which are carrying a good portion of the vehicle weight. Also the relatively low speeds typically used while on rails means little energy required to overcome the wind resistance experienced at normal highway speeds. (Fastest I've never seen a hirailer go is perhaps 15 mph)

However in actual use I suspect hirailer fuel efficiency is lower on rails. The frequent stops and long periods of idling typical for highrailer operation will drag down the mileage. Further, at usual hirail speeds the vehicle transmission probably never gets out of 2nd gear. So the engine never gets to operating in its fuel economy "sweet spot" - usually 35 - 40 mph for a pickup - while on the rails.

...FB

[Passenger]

... Fastest I've never seen a hirailer go is perhaps 15 mph ...

Due to safety concerns, or a physical limitation of the equipment?

[FarmallBob]

... Fastest I've never seen a hirailer go is perhaps 15 mph ...

Due to safety concerns, or a physical limitation of the equipment?

Don't know - it's just what I've observed over many years spent trackside. In fact most of the hirailers I see (generally track inspections....) are poking along at 5 - 10 mph.

...FB

[litz]

well, they're probably inspecting ...

Hi-Rails can scoot along at 20-30mph easily ... they do it all the time on NARCOA runs.

[John_Perkowski]

Ones I see on BNSF toodle along at anywhere from 25-50MPH, depending on make, model and what they're doing...