For my 70 foot long trestle that reached 8 feet above ground I used splined
cedar strips glued with Gorilla glue and staples to hold the curve until the
glue set up. This splined section is the support system directly under the
plastic ties and rail. I added cedar ties between each plastic tie on the
trestle.
Each thin strip was sawn from a 12 foot long 2 x 6 cedar board. I used 3/8"
x 1" strips to laminate my tie supports. Despite its inherent smooth curve
tendencies I still managed to get a slight vertical curve where I ceased
running on the level and started the less than one degree slope.
All the trestle was sprayed with a deck sealer. Where the track met the
ground I have 10 feet of splined roadbed before I transitioned to ballast.
This below ground splined section is coated with below ground fence post
creosote type latex emulsion. This coating must dry for a week or two before
placing on or below ground.
Regarding superelevation: I read in Garden Railways that superelevation
does not work well for our size trains. I believe part of the problem was
simply the lack of weight and the much simpler or non existant suspension
systems of our models. The article indicated more derailments occur with
super-elevated track than with flat track.
Gary Lane
http://www.angelfire.com/or/trainguy/ Pictures of the trestle
Charles Brumbelow wrote:
> Has anyone used the spline system of building roadbed for outdoor
> track?
>
> For those new to the term, spline roadbed is made by gluing successive
> narrow strips of wood together until the desired roadbed width is
> reached, then sand/plane the top surface smooth (and superelevated if
> desired). Spline roadbed tends toward generating its own easements and
> is extremely strong for its weight. Materials can be saved and drainage
> provided by alternating a row of spacers with a row of full length
> strips. External/waterproof glue would be needed, and rot resistant or
> treated wood would be highly desirable. I suppose one could make
> sectional roadbed for a portable layout if desired.
>
> Charles
