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

_________________________________________________________________________________
Gnome Miniature Engineering is located in Ontario, Canada, in a place that we acknowledge to be the traditional land of the Six Nations of the Grand River.

GME MODEL RAILWAY BRIDGES are multi-scale working structures for small railways rather than scale models. They are hand built from laser cut, brake formed parts, assembled by traditional solid riveting.

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 girders and underslung trusses for G and larger scales.

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

EDUCATIONAL MODEL TRUSSES: The truss bridges are available as educational models to demonstrate the principles and properties of trusses.

The model number (TR32 etc) indicates the type and length of the bridge deck in inches. For more information, please contact us at
gme@gnomengineers.com

Updated on 6th September 2020
_______________________________________________________________________

05 September 2020

GME news


The first GME bridge to be sold (a PL24) was sold by Winona Garden Railway of Guelph, Ontario in November 2009, and since then they have travelled around the world, mostly to the USA, but also to Turkey, the Czech Republic, the UK, Anguilla, and Tasmania. Production quantities have been small, but they have found a niche with people who like the real rivets and the fact that they are built by hand. Some have been complete specials designed to the customer's requirements, and many others have been modified standard designs. In fact, shipping a standard bridge has been a rare event.

After eleven years and hundreds of thousands of rivets, it is time to cut back. The last major order is now almost complete, an 0 scale display set that will include a bascule bridge and (probably!) the last plate girders to be built.

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

0 and S scale bascule bridges

The BA24 bascule bridge for 0 and S scales is an operating trunnion type with an opening of just over 18 inches (457 mm).  It is a balanced design using a cast concrete counterweight. It can be supplied for either manual or remote electrical operation using a DC gearmotor and chain drive with a torque limiting clutch. One lifting section (without approach spans) is still available.

24 August 2020

Where to buy GME bridges


Credit Valley Railway Company  in Mississauga, Ontario, has one TR32D bridge suitable for 0 and S scale in their store, available for in-store purchase and worldwide shipping. This is one of a pair built for double tracks:


Bigboyztrainz  in Hamilton, Ontario, has sadly ceased operations following the death of the owner, Scott Stewart. His remaining stock was returned to GME and has now been sold.

11 April 2020

Gnome on show

The 2020 Ontario Narrow Gauge Show  was to have been in Hamilton, Ontario, this year, but of course, has been postponed like everything else. If it can be rearranged later in the year, we hope to be there to display the last few bridges. It is a very special show, always well-attended and well worth the visit, with plenty of imaginative models and fine craftsmanship, as well as a good crowd of interesting people.

20 December 2018

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 1:20.3 scale

(Below) PL36 with deck for 1:20.3 scale

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 may still be available to special order. An example of the narrowest version of the TR42 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 a customer's installation.



18 July 2018

Through trusses for 0 and S scale

Extra height TR32 (32 inch span) trusses for 0 and S scales, with increased internal clearance for North American double stack container cars, have been built in single (TR32H) and double track (TR32DH) configurations. 

25 April 2018

Frank Grantham 1933 - 2018

We are saddened to record the death of Frank Grantham, a mechanical designer par excellence, who was one of the original partners in GME. He was responsible for the detail design of the basic structures of a series of bridges that continue to be shipped around the world, from Canada to Tasmania. Frank had served a craft apprenticeship in the UK, and we knew each other first as colleagues at a Canadian company building naval aircraft handling equipment. Following his retirement he helped set up Gnome Miniature Engineering, combining professions and hobbies. Always a fine designer, a meticulous model maker, a good friend and a most congenial colleague, he will be missed.

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

Custom bridges

A large proportion of our work has been to special requirements, such as this 1:8 scale steel static display bridge - a favourite project that went to Istanbul. It incorporated 7 1/4 inch gauge track parts from The Miniature Railway Supply Co.

































The most economical approach to a custom design is to base it on standard parts. 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 from 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 a 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

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.

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

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: elevated railway style (above) 5.75" (146mm) high, with the width to the user's requirement. The two truss tower types (below) are 12 or 24" high, but will now only be available until the component inventory is exhausted.
The group of PL36 girders and 12" piers above was commissioned by Bigboyztrains, Hamilton, Ontario, and is now in England.


15 June 2011

Individual girders

Individual plate girders to add to your structures are available in 12, 24 and 36 inch and intermediate lengths (305, 610 and 914 mm).  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.

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, 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 with negligible deflection.

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.