N Scale Workshop

Introduction

In the previous episode of the Prairie River Bridge series, I installed the large braces that go across the end posts of the outer two trusses. The end braces needed to be installed before adding the rest of the details on the ends of the main span. The remaining end details that I will be installing in this episode include the steel towers, short lateral struts, lateral cross bracing, tower bracing, bridge feet, stringers, and stringer bracing. Once these are installed, I will finally be able to start on building the bridge piers and the ballasted wooden deck.

Steel Towers

Center braces for the steel towers are fabricated using styrene from Evergreen Scale Models in a similar manner to the laced girders that form the three main trusses. Archer Fine Transfers N Scale Resin Rivet decals are applied to the stay plates and individual rivets are applied to the intersections of the lacing where they attach to the flanges as shown in Figure 1. Several thin layers of DecoArt Burn Sienna acrylic base coat are applied to the center braces before installation.

The steel towers are attached to the gusset plates at the ends of the three main trusses. Connector plates are cut from scraps of 0.010" styrene strips and attached to the backplate on the top of the center end post as well as the top of the back side of the center post of the steel tower. The center brace is attached between the pairs of connector plates, making sure that the steel tower is perpendicular the bottom chords of the trusses as shown in Figure 2. After touching up the base coat, the other steel tower and center brace are added to the other end of the main span.

Lateral Struts

Lateral struts are built similar to the other ones, starting with two strips of 0.030" x 0.010" styrene strip and two plates cut from 0.010" styrene scrap followed by a single layer of lacing cut from 0.020" x 0.010" styrene strip is added on the same side as the plates. Additional strips of 0.030" x 0.010" styrene strip are attached to the back and strips of 0.020" x 0.020" strips of styrene are attached to create the four "L" girders on the edge of the struts as shown in Figure 3.

Bridge Feet

The west end of the main span is supported by three pin support feet. Two scale 4' x 4' plates are cut from 0.010" styrene sheet. Strips of scale one-foot-wide 0.010" styrene are attached to the top of one plate and the other plate is fastened on top. Four connector plates are cut to shape from 0.010" styrene and attached to the top plate.

Separator plates are cut to size from 0.010" styrene sheet and fastened between the gusset plates. An end plate cut from 0.010" styrene sheet is added to the end of the center lower chord. The feet are attached using a styrene rod inserted into holes drilled through the feet and lower chords. The lateral struts and lateral cross braces are installed similar to the other ones toward the center of the main span as shown in Figure 4.

The east end of the main span is supported by two roller support feet on the outer trusses and a slide support foot on the center truss. The feet are fabricated similar to the pin support feet on the west end of the main span but have either rollers or slides between the upper and lower plates. Separators are installed between the gusset plates and the feet are installed using styrene rod as shown in Figure 5.

The remaining lateral struts and lateral cross braces are installed on the east end of the main span. Rivet decals are added to the gusset plates and the end plates on both ends of the main span. Several layers of base coat are applied to the unpainted surfaces as shown in Figure 6.

Stringers

Stringers and stringer braces are constructed similar to the other ones, using strips of 0.010" styrene. The ends of the stringers are supported on posts that attach to the plates on top of the steel towers. Braces fabricated from strips of styrene are added across the support posts and between the tops of the outer end posts and the tops of the outer tower posts as shown in Figure 7.

Conclusion

After everything was dry, I gave everything several thin layers of base coat and touched up any paint chips as shown in Figure 8. I still need to apply rivets and base coat the bottom of the bottom chords, but now that the ends of the main span are detailed, I can finally get started on the bridge piers and the ballasted wooden deck.