SALT CREEK TRESTLE – 1 -- GIRDERS

Over the past year, I felt an itch to get on with the signature scene for my railroad—Salt Creek Trestle.  That long steel trestle serves as a major inspiration for my layout.  Indeed, a photo taken there in 1973 serves as the background for this blog and another portrait sits along these words as the inspiration photo.  Salt Creek Trestle is one of the most accessible spots on the Cascade Line as it spans both the eponymous creek and Oregon Highway 58, the Willamette Pass Highway. 

SP Extra 8898 East descending in the Cascades, crossing Salt Creek Trestle in September, 1973.

With a two-month break from operating sessions, I could tackle this project which necessarily meant removing a portion of the mainline.  The project breaks down as bridge girders, trestle towers, underpinnings, and walkway.  This first post on the trestle concentrates on the bridge girders.

The three long trestles on my railroad each have an aluminum strap spine to provide strength and geometry control.  The bridge girders are mostly cosmetic, covering that spine.  The spine has been visible for the past two and a half years, supported by temporary risers and overlaid with temporary roadbed. 

The aluminum spines were rolled to the desired radius by my good friend from my California days, Richard Croll.  Richard models in multiple scales, from HO to 7.5-inch gauge live steam.  In that large scale, he has set up a machine shop that supports his work.  This was a case of using large-scale tooling (his rail bending tool) to HO-scale.  The spine was formed from a pair of 1/8 x ¾-inch aluminum straps, rolled and then separated by another 1/8 x ¾-inch spacer.

A RR-East crosses Salt Creek Trestle with a helper set tucked onto the front.  This is an efficient way for helpers to be returned to the base of the climb at Oakridge.

The temporary roadbed was sections of ¼-inch hardboard (my roadbed spline material) cut to the lengths of the future bridge girders.  This included the thirty-feet long sections that span the trestle towers.  I tacked the temporary roadbed pieces on top of the aluminum spine.  Fortunately, when I laid this out during initial construction, I accounted for the scale 30-feet long spans over the towers to be pure rectangles to fit the towers.  This left the longer spans between towers to account for the curve radius, so those sections had ends cut at angles.  This prior work with the temporary roadbed helped guide cutting the permanent model bridge girders to the right length.  The span outside the curve needed to be longer than the inside span.

Temporary roadbed tacked on top of trestle spine for Salt Creek Trestle.  The joints between temporary roadbed sections are just visible, with a scale thirty-feet segment as the second segment in from the left.

I used Central Valley plate girders (210-1903-1) for my bridge girders.  I stockpiled these over the years in anticipation of the need for my trestles.  Salt Creek Trestle has eleven separate girder sections.  With a clean slate, I might use the new Walthers steel trestle system or the ExactRail girders, but with a substantial inventory of the Central Valley parts, that is what I used. 

The girders were cut to length and appropriate end caps applied.  Most of the end caps used Evergreen styrene 1/16-inch angle strip.  I added Archer rivet decals to the angle strips to mimic the rivet detail on the rest of the girders.  The two girders for a trestle span were separated by a piece of 0.125 x 0.188-inch Evergreen styrene strip.  This fit under the top flanges applied to the Central Valley girders.  This produced the correct height when these “saddles” were placed on top of the aluminum spine. 

Trestle bridge girders being assembled.

Trestle girders test fit on top of the aluminum spine.  These are the same spans seen in the earlier photo of the temporary roadbed.

The completed trestle girders were painted aluminum, matching the appearance of Salt Creek Trestle from 1962 onwards.  Although my standard for most railroad structures on my railroad uses 1954 (late steam era) appearance as a guideline, I chose to diverge to a bit more modern for my big trestles.  The aluminum paint is what most operators and visitors will recall for these trestles, particularly the very easily viewed Salt Creek Trestle.  The saddle spacers were painted black, just as the aluminum spine.  This turns both the spine and the spacers invisible once the track is placed on the trestle.

I applied light rust weathering to the base of the girders using Pan Pastels.  This was my first use of Pan Pastels—I like them!  I chose the light rust weathering to match my 1973 photo.  Typical of most railroad bridges, the trestle has not been painted since that original 1962 paint job, so a lot more rust shows in photos today.  I wanted my “time-machine” to represent an earlier time,  so the light rust coating was applied.

The trestle girders were installed using adhesive caulk between the spacer saddles and the aluminum spine.  This fixed them in place, but still allowed for tipping the girder assemblies to level them side-to-side.  That leveling occurred when the trestle towers were placed.  Meanwhile, placing the girders on the spine allowed me to place track back over the trestle, although such placement needed to remain temporary for succeeding construction steps.

Salt Creek Trestle girders installed.