Custom and standard bridges for G scale, O scale, and garden railways

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GME MODEL RAILWAY BRIDGES: Gnome Miniature Engineering structures
are multi-scale working structures for small railways rather than scale models. They are hand built from laser cut, brake formed parts, and assembled by traditional solid riveting. Structures designed to your own requirements can be built at a reasonable cost when standard parts are used.

Standard bridges are built from corrosion resistant materials for year round operation on garden railways. They are ready to use, painted or unpainted, except for the installation of the track. They have been used with track from 16.5mm gauge for 0n30 to 63.5mm for Gauge 3.

GARDEN RAILWAY BRIDGES: plate girder bridges and underslung trusses for G and larger scales.

O and S SCALE BRIDGES: plate girders, through and underslung trusses, working bascule bridges.

EDUCATIONAL MODEL TRUSSES: The truss bridges are available as educational models to demonstrate the principles and properties of trusses. These will normally be supplied without paint finish or decks. Material and section data are available.

The model number (TR32 etc) indicates the type and length of the bridge deck in inches. For prices, availability, installation drawings and enquiries about custom designs, please contact us at
gme@gnomengineers.com

Updated on 26th July 2016 - posts updated
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01 June 2016

GME news

The first extra height TR32 (32 inch span) trusses for 0 gauge are finished and shipped. These have increased internal clearance for North American double stack container cars, and are available for single (TR32H) and double track (TR32DH).  All trusses now have additional gusseting to improve lateral rigidity.

If you are interested in curved plate girder bridges, please note that, just like many full size riveted bridges, GME bridges consist of short straight sections with timber decks supporting the curved track.

Please continue to visit Credit Valley Railway Company for 0 and S scale and Bigboyztrainz for G scale structures. All other enquiries as usual to gme@gnomengineers.com

17 April 2016

Gnome on show


The 2016 Narrow Gauge Madness  show in the village of Schomberg, Ontario was one of the best yet - excellent exhibits and the usual good crowd of  interesting people.  The bascule bridge always gets attention and advice on how to improve it, such as: "You want to be able to get a lawn mower through that bridge". I'm thinking about it.  This is a great show to see enviably accurate fine scale models built by talented craftsmen as well as quirky little railways that exist only in the fertile imaginations of their eccentric and interesting builders.

Thanks to Garden Rail (Issue 199) and Garden Railways (August 2011) for some friendly and encouraging reviews!

04 June 2015

How they are made

For the standard structures, each part is laser cut from aluminium alloy sheet, cleaned, deburred, brake-pressed, joggled if required, and then riveted into the assembly using solid rivets. Here is a plate girder rib as cut and after forming:

Parts are often altered from standard to suit particular variants, and this is mostly done by hand.

Below is a sub-assembly of an all steel custom bridge that went to a client in Turkey to display his 1:8 scale live steam locomotive (see bottom of the page):

21 May 2015

O, Gauge 1 and G scale plate girder bridges

Click on the drawing below to see a larger version:


Standard plate girder lengths (intermediate lengths available on request):
Model no.   PL12     12 inches (305mm)
                   PL24     24 inches (610mm)
                   PL36     36 inches (914mm).
Widths: 
                                 4 inches (102 mm)
                                 2.54 inches (64.5 mm)
                                 2.0 inches (51 mm).
A timber deck with attachment hardware, for standard or narrow gauge tracks, is included in the price.You can order any combination of length and width, and we'll be happy to discuss specials. The current maximum length is 36 inches (914 mm) for a single span without intermediate supports.
(Above) PL12M for G scale

(Below) PL36 with G scale deck

G scale and Gauge 1 truss bridges



These are available in three widths as deck trusses for the larger scales, with the timber deck included. The standard lengths are shown above, and others are available to special order. An example of the narrowest version of the TR42 built for NGT Models, with two PL36 plate girders, is shown below. This is 114 inches (2.9m) overall, and assembled with 1,274 solid rivets. Watch an animation of the bridge installation.



Custom bridges

A large proportion of our work is to special customer requirements, such as this 1:8 scale steel display bridge - a favourite project.


































The most economical approach to a custom design is to base it on standard parts. Contact us to discuss your ideas and requirements. A request for something you don't see in the illustrations will sometimes lead to a new product that will be of general interest. The picture below shows the first of many 'specials'; this one for a large 0n30 railway, using mostly modified standard parts.

Masonry viaducts appearing to be curved are common, but there was rarely a horizontally curved steel bridge until the development of modern welded box girders. Most bridges that appear to be curved are a series of straight sections, and this is how we build a curved bridge. For a sharply curved bridge, the girders will be trapezoidal in plan, as in the example for an 0n30 railway shown here:

Decks

Prices include timber decks consisting of transverse timbers with longitudinal guard timbers. Assembly is with nails, and screwed cleats secure the deck to the structure.


0 and S scale decks for indoor use are precision milled basswood sections from Mount Albert Scale Lumber, either stained to resemble fresh creosote or with a simulated weathered appearance.

This illustrations show four different red cedar outdoor decks after weathering for up to six years.
(above) L-R: (1) pictured after 6 years exposure, no stain, no preservative; (2) 6 years, stain with preservative; (3) 5 years, stain with preservative;  (4) 3 years, stain with preservative. They are exposed to sun, rain, snow, salt, cats, deer, raccoons, squirrels and birds. After 7 years exposure, the specimen on the left appealed so much to one customer that he asked for it to be installed on his TR42M. Happy to oblige! Properly drained, the cedar weathers well and keeps its strength.

The standard large scale decks are red cedar, stained or unstained. For Gauge '1' the transverse timbers are 5 inches (127 mm) and for 'G' they are 6.4 inches (162 mm) long, corresponding to roughly 13 feet (3,962 mm).
All decks can be supplied with short extensions to cover the gap between the bridge and the adjoining structure. Decks designed to your own requirements are also available.

27 January 2015

Prices and availability

Despite some supplier cost increases, prices will be held at last year's level as long as possible. Please e-mail us at gme@gnomengineers.com for the latest prices, availability, and discounts for multiple bridges.

The price includes the timber deck, installation hardware, and a coat of primer if requested. Shipping and insurance are extra, at cost.  Prices start at about Can$135 for a single PL12 plate girder bridge.

For quickest delivery of standard designs, please check with the retailers, who usually have a selection in stock. Standard bridges are usually shipped in 3-4 weeks, although there is sometimes a delay if parts are being re-stocked. Since they are hand built, delivery can be slower when we're busy.

01 November 2014

Where to buy GME bridges

Please visit our retailers' websites: 

Credit Valley Railway Company  in Mississauga, Ontario, has  GME 0 scale bridges on display in their store, and will take orders for the standard models, both for in-store purchases and worldwide shipping.

Bigboyztrainz  in Hamilton, Ontario carries G scale and larger bridges. In-store purchases and worldwide shipping available for all products.

Gnomes...

If you arrived here looking for gnomes, we have to say that's just the name, not the product. However, we are happy to recommend a friend in the gnome business deep in the Muskoka forests of Ontario, who will make the most delightful gnomes in all shapes and sizes for you.

03 December 2013

Bridge piers




Bridge piers are in three types: intermediate (left), free standing (above) with a standard height of 12" (305 mm), and viaduct (top) 5.75" (146 mm) high, suitable for elevated railways. They will usually be supplied with the bridges and priced as a package.  The elevated railway piers will be supplied to fit standard bridges or the customer's requirement  where a greater width may be needed.

28 December 2012

Scales and gauges

0 scale is well defined, being 1:43.5 in Europe and 1:48 in North America, but ‘G scale’ is commonly used to describe a range from standard gauge 1:32 (Gauge 1) to narrow gauge 1:20.3 scale, all using 45 mm gauge track.  Many of our bridges are adaptable to all these scales, so please let us know your specific need when enquiring about availability.

For a good description of the principal scales and gauges, Roundhouse Engineering welcomes visitors to their website. The page headed 'Scales and Gauges' in their technical section provides plenty of helpful information (thanks to Chris Loxley).

05 November 2011

0 and S scale bascule and truss bridges

The BA24 0 scale bascule bridge (sometimes called a drawbridge) is an operating trunnion type with an opening of just over 18 inches (457 mm).

This model may be discontinued when the present stock of parts is exhausted. Until then, the basic structures (pedestal/trunnion frame/ lifting section) will be available for completion and detailing by the customer, at a lower cost than the complete bridge, of course.

The bascules can be used as road bridges for Gauge 1 as well as 0 scale. Let us know if you would like this version, and it will be supplied with a close timbered deck.

The basic range of 0 scale through truss bridges for 1:48 and 7 mm:ft. is shown below. Some customers are finding that these bridges serve well on S scale railways.

0 scale truss bridge dimensions:
Span:                              TR24    24 inches (610mm)
                                       TR32    32 inches (813mm)
                                       TR42    42 inches (1067mm).
All 0 scale through trusses are now available in double track versions
Inside width:                 3.75 / 7.25 inches (95 /184mm)
Outside width:              4.45 / 8.03 inches (113 / 204 mm)
Inside height from deck:        5.0 inches (127 mm).

15 June 2011

Individual girders

Individual reusable plate girders to add to your structures are available in 12, 24 and 36 inch lengths (305, 610 and 914 mm); other lengths available to order.  A 1/2"x 1/2"  mounting angle is riveted to the inside, and stainless steel screws are provided for attaching the girders to your own deck. Quantity discounts apply to standard girders and custom models built from standard parts.

These girders can be packed more compactly than complete bridges, substantially reducing shipping costs.

26 March 2011

Kits, parts and drawings

We’re sometimes asked if we supply kits and parts for our bridges. Normally, we don't, because assembly calls for equipment not usually found in the model railway workshop. Although many parts are standard, some are altered items that need additional work, and there can be workshop folklore in the assembly. However, if you have a project where GME parts might be useful, please contact us to see if we can help.

We'll be pleased to supply reduced scale PDF versions of installation drawings to help you choose a bridge, and if you wish to build your own, you are welcome to use them as a guide, though we don't supply the CAD files for them.

26 February 2011

Paint

The most popular paint finish is flat black, but red oxide, grey primer, flat black or unpainted finish are also available. All structural materials and fasteners are corrosion resistant, so the bare metal is always satisfactory outdoors.  Unpainted bridges are cleaned before delivery, but customers who paint their bridges should ensure that the surface is clean and dry before painting - wash them in a strong detergent followed by thorough rinsing and drying. Use a primer formulated for aluminium alloy surfaces and allow ample drying time in a warm, dry environment before top coating.

15 February 2011

Bridge strength and stiffness

GME bridges are certainly quite light...


But they are strong...
The original design specification said there must be negligible deflection with a 25 lb (11 kg) locomotive at the middle of the longest span. The picture shows about 74 lb (34 kg) of bricks stacked at the middle of a TR42. We'll do some more scientific testing, but we feel your heaviest rolling stock will be safe!

28 September 2010

A knitted bridge

Nothing to do with GME this time, but here is the Main Street Bridge in Cambridge, Ontario; normally just an unattractive mass of Depression era concrete with a false bowstring girder superstructure. However, for a few weeks in autumn 2010, it was transformed by hundreds of local residents into a lively and colourful collage of knitted items of all kinds, celebrating the town's history in the textile industry.

08 March 2010

Installation kits

A set of support plates and cleats tailored to your installation can be supplied with your bridge. A small charge may be made for more complex sets. They allow for thermal expansion and contraction over a wide temperature range for outdoor applications. 

25 May 2009

Track

The bridge decks are designed to accept the popular makes of prefabricated track, such as Aristocraft and LGB for 45 mm gauge, and Peco, Atlas, Gargraves and older Lionel for 32 mm. Guard timbers are provided on all decks, and the track fits between them. For a more prototypical appearance, the rails can be chaired or spiked directly to the deck cross timbers.

Note: If you use Lionel Fastrack, please let us know before you order. Single track through trusses may need some adjustment to the deck, but double track through trusses are not suitable if 6 inch track centre spacing is used.