DRRR Pier

Pier and Dock
The Deep River RR Pier and Dock – in this case it’s both. From my understanding (minimal) .. the pier is the structure supported on piles and the dock is the area of water alongside where the ship loads/unloads.

I’m going to basically follow the design of a railroad trestle and modify it as needed for a pier (that’s mainly due to an excellent resource “A Treatise on Wooden Trestle Bridges” by Wolcott Cronk Foster published 1897 [1].) Up to about 10 ft. in height. Wooden trestle bents generally consisted of vertical piles .. above 10 ft. in height they would drive the outside piles at a batter of from 1 in. to 3 in. per foot. I will be following the trestle design for bent caps, stringers and so on.

Pile Trestles
Below are excerpts from the book matched up with a diagram and dimensions for a Standard Pile-Trestle for the Denver & Rio Grande Railroad. I had planned to modify the timber dimensions to better represent a narrow-gauge railroad but noticed that the diagram shows the trestle carrying both standard gauge and narrow-gauge rail. That caught my interest – While I don’t have any plans for standard gauge .. darn .. I could add that extra rail and show it rusty .. as if either the rest of the standard gauge had been pulled up in the past or .. perhaps they engineered the bridge to have dual gauge for ‘the future’ .. the biggest thing for me would be that – for a model – it would add a bit of ‘cool’.

I put that aside for further thought while I did some research on a small crane. My intention was for a small crane at one end of the pier to load/unload to .. what? If to vehicles then you need a loading area next to the track. It didn’t seem unreasonable to me that this would be required. what about ships? They could use their own cranes to move from ship to dock. Thinking about that I looked back at the drawing of the dual gauge track on the DRGW trestle and realized that possibly, I could have four rails (increased coolness) with the crane running on the outside rails.

Edit: 5 rails! If the crane uses a belly-mounted hoist then it needs another outrigger rail on the other side of the vehicle deck (dock side) so the crane can move loads to the dock area to the rail area.

[1 – pg 5] “…Pile-trestles are seldom used for heights above thirty feet…” – Well .. good. Mine is right at 10 ft. (insert smile here)

[1 – pg 6] “Round piles are, as a rule, from 12 inches to 15 inches across the butt after being cut off, and when they are wider than the cap, the portion which projects on either side should be adzed off to an angle of at least 45°” – That makes it easy as I can use 1/4 in. doweling from Lowes

[1 – pg 40] “It is well to make solid caps of at least 12 in. x 12 in. timber and 14 ft. long. Where the timber is inclined to be weak or brittle, they should be 12 in. wide by 14. in deep.” – I might pick up some 1/4 in. sq. stock at Lowes for this too. While not as soft and easily worked as basswood – most of the caps will not be seen except end on – and it’s both available and cheaper then basswood.

[1 – pg 41] “Bents should be spaced at such a distance between centers as will use the length of timber easiest to obtain for stringers inthe most economical manner. The distance varies from 12 ft. to 16 ft.; spans of 14 ft. and 15 ft. being the most general.” – I decided on a 11 ft. span – based on the availability of easily obtainable stock (craft sticks) I could use for the stringers.

[1 – pg 43] “A stringer should be placed immediately beneath each rail, and in order to guard against defective timber it ought to be “split” or composed of two or more pieces. These pieces should be separated from each other by either cast-iron washers or spools, or wooden packing-blocks, or both. A considerable difference exists in the present practice as to the amount of separation. It varies all the way from nothing to 3 in. From 1-1/2 in. to 2 in. is a very good distance.

Narrow-Gauge Engine Weight
This next bit is ‘pesudo-engineering’ .. or .. ‘imagineering’ .. please .. engineers don’t freak on me! I’m having fun playing with numbers here.)

EBT Mikados weighed between 112,00 and 163,000 lbs. A RGW Mike (K36) around 185,000 lbs. Light Mikados built for the Walbash in 1912 weighed 266,000 to 290,000 tons. Later heavier Mikados at the Walbash weighed around 338,000 tons.

At the extremes that 112,000 lb EBT Mikado weighed 33% of the heavy Walbash Mike. The RGW K36 at 185,000 lbs weighed 70% of the lightest Walbash model. A little math tells me that to weigh 33% of another it would have been 69% the width, height and length. That RGW K36 at 70% of the weight of the lightest Walbash would have been 89% of the width, height and length.

I’m playing with numbers here but the book the D&RG trestle was published in 1897. With that in mind I am going to compare that 112,000 EBT Mikado with the light Walbash Mikado which weighed 266,000 lbs. .. which comes to 42%. A locomotive that is 42% the weight of another .. and for the purposes of this fantasy, reduced proportionally .. would be 75% of it’s full-sized sister in width, length and height.

Size of Stringers Needed
In “Railroad construction: theory and practice” pub 1922 it has the following concerning stringers.

Disregarding all refinements as to actual dimensions, the ordinary maximum loading for standard gauge railroads may be taken as that due to four driving-axles, spaced 5’0″ apart and giving a pressure of 40000 pounds per axle. This should be increased to 54000 pounds per axle (same spacing) for the heaviest traffic.

Using the calculations that the Narrow-Gauge locomotive weighs 43% of the Standard-Gauge locomotive (and keeping the 5’0″ wheel spacing) we get a pressure of 16800 pounds per axle.

We then get a chart for ‘Stresses on various spans …’ for spans of 10 to 18 ft. Just below the chart it refers back to the earlier 54000 pounds per axle for heavier traffic .. where it states ..

… there will be no appreciable error in assuming the corresponding values, for a load of 54000 lbs. per axle, to be 54/40 of those given in the above tabulation.

Ok. Then for my 16800 lbs. per axle load for my narrow-gauge then the corresponding value would be 17/40 or 42.5% .. of course.

From the chart, with a span of 10-ft. the load on one cap will be 41200 lbs. For our narrow-gauge locomotive that will convert to 17304 lbs. If the stringers and cap are made of long-leave yellow pine (why not), the allowable value, according to Table XXI, for “compression across the grain” is 260 pounds per square inch; this will require 67 square inches of surface. If the cap is 12″ wide (it is), this will require a width of 5.6 inches.

From the chart showing ‘Stresses on various spans …” we find that (for Standard-Gauge) and a Span of 10 feet, the Max. movement, ft. lbs is 51500. Multiplying that times 42% for Narrow-Gauge we get 21630.

For rectangular beams. Moment = 1/6*R’bh2

21630 X 12 = 1/6 X 1300 X 5.6 X h2
from which h = 14.7-in.

My strip-wood stock I have is 1/8-in x 1/4-in .. or .. 6-in x 12-in full size. Let’s try replacing that 5.6-in width with the 6-in and see how that changes the stringer height.

21630 X 12 = 1/6 X 1300 X 6 X h2
from which h = 14.2-in. .. still not good enough but getting closer.

If we double the stringers so we have 12-in. and run the formula again …

21630 X 12 = 1/6 X 1300 X 12 X h2
from which h = 10-in.

So. We need a pair of stringers, each measuring 6-in. x 10-in. The stock I have that measures (scale) at 6-in. x 12-in. will do fine! Yea.

Ok Ed. You like playing with numbers .. but .. so?
The D&RG trestle lists the stringers as “8 in. x 16 in. x 32 ft.“. In the book it states that “Bents should be spaced at such a distance between centers as will use the length of timber easiest to obtain for stringers inthe most economical manner. The distance varies from 12 ft. to 16 ft.; spans of 14 ft. and 15 ft. being the most general.“. Looking back at the D&RG trestle having stringers of 32 ft. that pretty much tells me they spaced their bents at 16 ft. OK?

From “Wood Structural Design Data” pub 1986 in the Safe Load Tables for 16 ft. spans we can get some more numbers to play with. Hooray.

For “Allowable unit stress in extreme fiber in bending, psi. let’s go with the 1300 psi. from the earlier Chart XXI. From the chart (using the 1,300 psi. column) we find that a 8 in. x 16 in. beam will safely support 16,266 lbs Total uniformly distributed load .. and 1,016 lbs. load per linear foot of beam. Cool.

With the Narrow-Gauge load at 42% of Standard-Gauge as calculated earlier we can modify those numbers. 42% of 16,266 is 6,832 lbs and 42% of 1,016 is 427 lbs. Again .. much coolness.

Now. I went back to the chart for 16 ft. spans and went backwards looking for these numbers.

A 6 in. x 12 in. beam spanning 10-ft. and using 1300 Fb will give us 10,506 lbs and 1050 lbs. respectively.

Looking back we see that each rail is supported by two stringers. So the total load needed to support is 20,204 lbs. Two 6-in. x 12 in. stringers, each supporting 10,506 lbs is 21,012 lbs. Shazam. Hooray and all that.

Stringer Results
So. From two different directions I calculate that two 6-in. x 12-in. stringers under each On30 rail will be fine. There you go. Pseudo-Engineering at it’s best!
Basic Dimensions
Length: 17 inches .. that will be enough to run the length of the ‘water’ section stopping just short of the far bank. That will represent a 68 foot long pier/dock.
Width: I ended up with a 5-1/4″ width. this is room for the narrow gauge track with a 9-ft traveling crane straddling the narrow gauge .. with room for a truck to drive onto the pier for loading/offloading and finally an outrigger rail on the dock side. That should provide plenty of interest.
Progression: 14/06/12
Edit: Found some information in a book titled ‘Wharves and piers: their design, construction and equipment‘ – by Carleton Gren pub. 1917. That would be a “fender Timber” that I was looking for. I found several drawings of them – 8×8 in.; 8×12 in.; 6×10 in. In the drawing to the left from Depot Harbor, Ont. there are several items of interest. The fenders are 10×12″ in two rows about six feet apart. They are bolted on with 1 in. screws spaced 5 ft. apart. The Bollard is also shown, which I had forgotten about.

Looking at various drawings I think the best bet for the dock side of the pier is to double up on the pilings there so you get a vertical surface to which I can mount the fender timbers.

Note: I was at Lowe’s yesterday and knowing they had large timbers for sale I wandered over there. The 6 in. x 6 in. timbers are BIG. My little docking area isn’t for giant ships but small boats as the pier is only 10 ft off the water. 6 in. timbers would be quite large enough .. thank you very much!

Pier and Dock
Pretty happy with this .. about ready to start modeling. I’m thinking thought how to approach this. No matter how much you try .. that 17 inches of pier will be a bitch to get straight. I think what I will do is follow what Troels Kirk did .. drill holes for the piles .. insert then pull up till they touch a straight edge .. or some-such.

Anyway. Figured that the one part that was problematic .. was the support for that dock-side outrigger rail. I finally decided to simply replace the stringers/ties with a 12″x12″ timber. Problem solved. I’ll cover that later.



Comments

DRRR Pier — 9 Comments

  1. There is a pier in the future of my layout and this is the article that I will go to before building it. I admire your modeling and thank you for taking the time to share your techniques.

    Phil
    Graham, NC

    • Phil. Thanks. I wash’t sure where Graham, NC was so I pulled it up in Google Maps. Ha .. you’re darn close to my the imaginary Deep River area of my Railroad. I need to come up there and do some exploring of the area.

  2. My daughter and I are planning (imagineering if you will) an “Outer Banks Railroad” which will need piers, trestles and such. So your work is quite relevant to our plans. At the moment a rolling lift bridge between Roanoke Island (Maneo) and Nags Head and a swing bridge at the inlet at Pea Island are on the agenda. The rolling lift bridge will be shared with highway traffic. Railroads actually serve(d) Elizabeth City to the north, Cedar Island to the south, and a logging camp at Buffalo Landing to the west of Maneo…if my memory is correct.

    • Charles – always welcome someone else to ‘imagineer’ 🙂 .. my hope in part is that these threads will get others to comment, suggest .. basically .. help imagineer with me.

      That book I linked above is very helpful. That Army TM (linked in part 6) is very useful since .. IMO .. it is for a soldier who had previously been asking “do you want fries with that” .. and takes him and shows him how to build a wharf, trestle etc.

  3. Copied over from Yahoo – Buildingsandstructures
    —————
    Hi Ed, et al.

    A nice pier like that begs to have an interesting vessel moored alongside.

    I’ve been admiring three ship kits in 1/48 that are the right size to
    appear on a layout. All are plank-on-frame, and cost $130 to $160 if you
    shop:

    Billing Marie Jeanne
    Billing Lilla Dan
    Dumas George Washburn

    Both the Billings are wilndjammers made for blue water. The Washburn was a
    barge tug on the Hudson, and thus appropriate for inland waterway shipping.


    Mark Nickelson
    a.k.a. pby5dumbo, hebrews413
    649 Lowell Drive, Marietta, GA 30008
    h) 770-422-9240
    cell) 912-222-6827

  4. Copied over from Yahoo – buildignsandstructures group
    —————–
    The jetty looks good but two comments. Timber piles tend to have been squared up somewhat rather than being circular, the tops are then tapered a little as though with a large pencil sharpener so that they can be fitted with an iron hoop to protect from splitting especially while driving. Secondly a jetty is sure to have diagonals and/or raking piles to take the horizontal forces imposed by the berthed ships. One row of raking piles attached to the heads of the piles at the front face should suffice. There may also be dolphins, strong points for mooring ships to. These give support to ships extending beyond the jetty because access is only required to the hold area of the ship. The side of the jetty may have rails at a lower level than the top with old truck tyres or even fairly sophisticated fendering. Suitably sized bollards are also essential. Ships are moored with ropes direct to the jetty at bow and stern but almost more important are the springs which run fore and aft. All ropes should be as long as possible because this saves adjustment to allow for the rise and fall in the tide so tieing to a bollard six feet away is a bad idea, two ropes each fifty feet long or more running diagonally from ship to shore is much better.

    Archie

    • Some musings on Archie’s comments ..

      • Timber piles tend to have been squared up somewhat rather than being circular, the tops are then tapered a little as though with a large pencil sharpener so that they can be fitted with an iron hoop to protect from splitting especially while driving. – There is an excellent drawing of what you are talking about in the Army TM. They cut off the tapered bit after driving the piles.
      • Secondly a jetty is sure to have diagonals and/or raking piles to take the horizontal forces imposed by the berthed ships. One row of raking piles attached to the heads of the piles at the front face should suffice. – Need to look into this more.
      • There may also be dolphins, strong points for mooring ships to. These give support to ships extending beyond the jetty because access is only required to the hold area of the ship. – if I had the room that would be cool. Found a neat plan for a dolphin in the Army TM .. again, I have no room for those. They would be neat IF I did have the room.
      • The side of the jetty may have rails at a lower level than the top with old truck tyres or even fairly sophisticated fendering. – That’s coming. Have a pair of 6×6-in timbers for that purpose. I’m already planning for old tires tied to those too.
      • Suitably sized bollards are also essential. – There’s a pic of a nice bollard in “Wharves and piers” – I copied that one in Sketchup – bollard
      • Ships are moored with ropes direct to the jetty at bow and stern but almost more important are the springs which run fore and aft. All ropes should be as long as possible because this saves adjustment to allow for the rise and fall in the tide so tieing to a bollard six feet away is a bad idea, two ropes each fifty feet long or more running diagonally from ship to shore is much better. – Found a nice diagram showing what you are talking about –
  5. I’ll echo others in thanking you for the effort in going through the pier building process. I’m constructing a car float pier, and have looked at the references you cite. Good stuff, and invaluable reference material. Kept me from reinventing the wheel, and I should have a much better model to boot.

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