We often talk about adjusting your minimum radius based on the type of equipment you intend to run, but I don't recall reading any similar discussion on vertical clearance.
On the section of the N&W I'm modeling, equipment is specifically restricted to no larger "plate C", which limits the height of equipment to 15' 6". This comes out to 2.14" in HO. The NMRA "classic" table specifies 3-1/32", which I understand is still tight in a spot that needs to accomodate fingers, but when finger access isn't required I've got almost an inch to spare.
I'm thinking that "plate C" dimensions would not only provide me a little extra flexibility, but would also result in a more realistic layout.
BTW, on "plate C" track where equipment is limited to 15'6", what would be the clearance above the rail standard?
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An example:
I have read about covered hoppers coming out of this tunnel being too hot to touch from rubbing against the walls.
You can set your clearances to whatever standards you wish. I deliberately created places which restrict certain equipment, like these silos which require idler cars for switching due to limited overhead clearance:
...or this wye, with a low bridge over it. It will accommodate any of my locos or cabooses, but some MoW equipment and some open loads are strictly prohibited:
Similarly, this tunnel is off-limits to some open loads...
...such as these automotive frames:
These cars move between two unmodelled industries, and because of the special equipment racks, cannot be turned, making their routing very specific.I also have side clearance restrictions which limit plows and spreaders from certain tracks, mostly at station platforms, and others which prevent locomotives from entering industrial structures during switching maneuvers.
Wayne
This is what I've always done: I take what I believe to be my tallest and longest item and use it to make sure it clears any bridges or tunnels etc. If the tallest can clear, everything else should by default.
I have some double stacks I use for height and for long cars, I use 89' autoracks.
Rio Grande. The Action Road - Focus 1977-1983
carl425BTW, on "plate C" track where equipment is limited to 15'6", what would be the clearance above the rail standard?
Well, it's my understanding that the height restriction is "hieght above railhead", so the clearance above the rail would be 15'6".
I was thinking that they would allow for some space between the top of the equipment and the bottom of the obstruction.
I would think you would have to be careful where you put tight clearance objects on your layout. In some places it would look like you screwed up taking measurements.
I am building a new layout at the moment. I know from experience that there are two items I own that require an inordinately high clearance above the rails, my Trix GG1 with extended pantograph and the 150 ton wrecker. Actually, three things...my Trueline CPR caboose has a really tall stack that I learned about the hard way.
It's just something else in a long list of plates we have to keep spinning on the rail when we're laying the foundation for our track system. Some tunnel portals will have to be widened if they can't be perpendicular to the tangent line where the rails pass through them, or if the clearance overhead is likely to be low, I haul out the Trix, place a length of Code 83 down on the sub-roadbed, place the GG1 under the portal, and look for a reasonable clearance. I have placed the base of such portals on a carved chunk of plaster or foam "cement" to elevate them sufficiently. Painted up, it looks reasonably realistic.
SouthPenn I would think you would have to be careful where you put tight clearance objects on your layout. In some places it would look like you screwed up taking measurements.
Cars and locomotives got bigger over the years, and not all industries or restricted clearance areas of railroads needed to be altered to accommodate the changes. I'm modelling the late '30s and all areas of my layout are accessable to any cars suitable for interchange, provided that there are no restrictions on them listed in the ORER. My frame rack-equipped cars would be an example of the latter.The steel plant at which I worked had many interchange cars within the plant, either delivering material or for shipping out finished product. While these cars would naturally be directed to the appropriate area, there were many places where, for example, 50' or 60' boxcars wouldn't fit due to tight curves and narrow or low clearances.Even the plant's fleet of locomotives had modified cabs to allow them to clear the underside of the cabs of overhead cranes in some of the older mills:
Newer mills had much more generous clearances:
The NYC was a good example of a major railroad with many restrictive overhead clearances - that's why their Niagaras had a stack only 3" high.
I guess I've been thinking of my NMRA standards gauge as being carved in stone rather than just being stamped out of steel. I had no idea that so many routinely ignored the commandments.
Keep in mind when discussing clearances that in recent decades this applied just to the rolling stock being able to safely pass under obstructions.
In the past, there was the need to clear crew on top of equipment. So that number would be the height of the car, plus whatever additional needed to do that, maybe say another 7'. That was the reason for tell-tales, for instance. Now that is basically irrelevant, so only the height of the car itself matters.
Mike Lehman
Urbana, IL
Note that some manufactured models over the years have been slightly out-of-scale (and many of these are over-height). Might be worth including some safety margin.
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