A WORD ABOUT BRACING PART A - BUILDING A STRAIGHT, PILE BENT, OPEN DECK TRESTLE. Built in Place, Straight

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1 BUILDING LARGE SCALE TRESTLES You have many options when building a large scale trestle. The choices you make may be based on the prototype you are modeling; the era or industry you are modeling; or, simply your personal preference. The first choice is PILE BENT or FRAME BENT. For the purposes of our discussion, a pile bent has legs that go directly into the ground, as if they were driven into the ground by a pile driver. Pile bents may have round legs or square legs; however, round legs are more common. Frame bents have horizontal sills that intersect the legs. They also have a sill at the bottom, upon which all the legs rest. Frame bents may have round legs or square legs; although square legs are more common. Another option is CURVED or STRAIGHT. This all depends on what alignment is required. highly recommended you build the one described in Part G. If you are unsure what trestle configuration to build, it is Also, the decking is optional: OPEN DECK or BALLASTED DECK. You also have the option of building a permanent trestle directly into the layout stored during certain seasons of the year (BENCHTOP). (BUILT IN PLACE), or building a trestle assembly that can be lifted out and These instructions are in different parts, to address combinations of the different choices. Built in Place Trestles Part A - Straight, Pile Bent, Open Deck Trestle Part B - Curved, Pile Bent, Open Deck Trestle Part C - Curved or Straight, Pile Bent, Ballasted Deck Trestle Part D - Curved or Straight, Frame Bent, Ballasted or Open Deck Trestle Benchtop Trestles Part E - Pile Bent, Ballasted Deck, Trestle Assembly Part F - Pile Bent, Open Deck, Trestle Assembly Part G - Frame Bent, Open Deck, Trestle Assembly Part H - Frame Bent, Ballasted Deck, Trestle Assembly A WORD ABOUT BRACING These instructions show bent-to-bent diagonal bracing in all possible locations. This might be a little more than is needed, but given the consequences of a failure, not a bad idea. Prototype railroads often reduce their material costs by alternating the diagonal bracing. Girt Anchor girts to terrain Terrain Another way to reduce the diagonal bracing. The Rio Grande Southern (RGS) rarely, if ever, used diagonal bracing. It is strongly recommended that a trestle like this have the girts anchored to the terrain, perhaps at an abutment. This will keep the bents from buckling. PART A - BUILDING A STRAIGHT, PILE BENT, OPEN DECK TRESTLE 1 Ballast or roadbed Temporary support may be required Built in Place, Straight 2 Line up with top of roadbed or ballast Drive or set 2" x 4" to hold ballast and support track Ballast retainer Assemble the track that is crossing the trestle. Hold it in place and determine the alignment required. Assemble all the track in the area to make sure the alignment is OK. Prepare a retaining wall for the ballast or roadbed that is on solid ground. Drive a 2" x 4" into the ground. This provides a solid base for the track as it meets the trestle. Page 1

2 PART A - BUILDING A STRAIGHT, PILE BENT, OPEN DECK TRESTLE (cont'd) 3 4 Support if required Ballast retainer Use piece of stringer stock to locate trestle support Build trestle guide Locate first "bent" at abutment. Attach 2" x 4" trestle support to face of ballast retainer W Mark bent locations Attach a 2" x 4" trestle support to the face of the ballast retainer that will support the trestle. Locate to top of the 2" x 4",.667" (the stringer height) below the track support surface. 5 BUILD ABUTMENT ASSEMBLIES Many different materials can be used to build the aburments. The next two steps show an easy to build a trestle bent abutment. The trestle bent provides the structural support and the planking retains the fill and ballast. Use the track as a guide to cut a template for the trestle. A good material is 1/4" to 3/4" plywood or hardboard. Make it about an inch narrower than the length of the top cap you will be using. W should be about 3.5". 6 Brace stock applied to back of bent Top Cap Bracing Legs Use the same techniques for building a trestle bent to build the abutment structure in the trestle jig. Insert the top cap and glue the legs in place. 7 8 Use scraps by placing joints behind legs Remove the bent from the jig and turn it over. Apply bracing material in a staggered pattern to the back of the trestle bent. Support trestle guide if necessary Bent Number Height Install the trestle abutments at each end of the trestle. Attach with screws to make them easier to repair and replace. Install the trestle guide and measure the bent heights. Record the heights. Make sure the guide is level. Support it if necessary. Page 2

3 PART A - BUILDING A STRAIGHT, PILE BENT, OPEN DECK TRESTLE (cont'd) 9 Make legs longer than your measurements. 10 Wood or metal anchors help legs stay rigid Use the trestle bent instructions to build the pile bents you need. Make the legs 2" to 3" longer than your measurements. 11 Rubber bands hold bents to trestle guide If you wish, attach anchors to the bottoms of the legs. Use extra braces that attach to the legs. This will help anchor the legs in the ground or mortar. 12 Use a torpedo level to make sure bents are vertical Scoop out holes in the ground for the legs. Suspend the bents from the trestle guide using rubber bands. Scoop out terrain if necessary Install side bracing Anchor legs with mortar, dirt, or gravel Use mortar or dirt to anchor the legs. Make sure any mortar does not interfere with the braces installed in the next step. Chamfer or round off upper edges. This enhances the look of separation. Install girts After the mortar has dried, remove the trestle guide and install the girts and side bracing. Adjust the terrain if necessary. Trestle guide Use the trestle guide to build the stringer assemblies. Put the joints at the bent locations. Use glue and nails to hold the stringer assemby together. Page 3

4 PART A - BUILDING A STRAIGHT, PILE BENT, OPEN DECK TRESTLE (cont'd) " x.443" Brace stock (2x) 16 Locate registration pins on outside of rail #4 Flat head sheet metal screw 1/2" x 1/2" Leg stock Attach stringer assemblies to trestle support Install the stringer assemblies. Attach them to the bents using #4 x 1-1/4" flat head sheet metal screws. Drill 1/8" pilot holes and countersink them. Use a temporary spacer as shown to set the distance between the stringers. Also attach the stringer assemblies to the trestle supports at the ends. Lay the track in place on top of the stringers. Install track registration pins if there is a chance the track will shift off the stringers. Drill pilot holes and insert 1-1/4" finishing nails to keep the track in place. This completes the trestle. 1 PART B - BUILDING A CURVED, PILE BENT, OPEN DECK TRESTLE Track sets the path of the trestle Built in Place, Curved or Straight 2 Support track if necessary Mark the ends of the trestle on the track 2" x 4" Ballast/roadbed 2" x 4" Trestle support retainer Lay track in place. Install 2" x 4" ballast retainer as shown in Part A, Steps 1-2 (Page 1). Install 2" x 4" trestle support as shown in Part A, Step 3 (Page 2). Cut to length marked on track 3 4 Place track where the trestle will go. Support it in the middle if it snags. Use rigid track couplings like those made by Split Jaw Products. Mark the ends of the trestle span on the track. Equal distance between bents Bent locations Trestle guide Sketched center line W Lay the track out on the trestle guide material and trace around the ties. draw the outline of the trestle guide. A good width is 3.5". Sketch the centerline of the trestle. Locate the trestle bents at equal distances along this center line. Cut out the trestle guide. Set the curved trestle guide on the trestle supports and check the alignment and the fit. Use a temporary support if necessary. The trestle guide should follow the path of the track. Page 4

5 PART B - BUILDING A CURVED, PILE BENT, OPEN DECK TRESTLE (cont'd) 5 6 Mark where the rails cross the top caps Build and install the abutments, bents, and bracing as described in Part A, Steps 5-13 (Pages 2-3). 7 Use bent-to-bent assemblies to build the curve in straight sections Assemble straight sections as shown in Part A, Steps 14 and 15 Place the track on top of the trestle top caps. Mark the top caps where the rail crosses each of them. These marks represent the "average" location of the stringer segments. 8 Build stringer assemblies similar to those shown in Part A, Steps 14 and 15 (Pages 3 and 4). Cut sections of the stringer stock to span the distance between the top caps. Stagger the cuts on the ends such that there is always at least one piece of stringer stock resting on a top cap. Attach them with #4 x 1-1/4" sheet metal screws. Drill 1/8" clearance holes in the stringers and countersink the holes. OPEN DECK STRINGER DETAIL If necessary hold the track in place with finishing nails as shown in Part A, Step 16 (Page 4). Fasten three stringer elements together Rigidly attach both ends of the stringer assembly to the top cap Make sure one of the ends has two stringer elements attached to the top cap Page 5

6 PART C - BUILDING A PILE BENT, BALLASTED DECK TRESTLE Built in Place, Curved or Straight 1 1/8" thick aluminum plate Ballast 1/2" x 1/2" Ballast retainer The Black Bear model of a ballasted deck 1 2 " Trestle top cap The Santa Fe prototype ballasted deck 1 2 " Trestle top cap There are a lot of possibilities for detailing a ballasted deck. The Black Bear design provides the functionality of a ballasted deck with a simplified structure. 2 Track sets the path of the trestle 3 1/2" to 1" Another option is to allow more space now and shim it up later. 1/8" 1/8" 2" x 4" trestle support 2" x 4" Ballast/roadbed retainer Lay track in place. Install 2" x 4" ballast retainer as shown in Part A, Steps 1 and 2 (Page 1). 4 Abutments are optional 5 Attach 2" x 4" trestle supports to each of the ballast retainers. To build the Black Bear style ballasted deck, place them 1/8" below the top of the ballast retainer. If you wish to experiment with a more prototypical ballasted deck design, position the track support lower. You can fine tune the location later with pieces of shim. Mark the ends of the trestle and the top cap locations on the rails and ties Build the trestle as shown in Part A (straight trestle) Steps 4-13 (Pages 2-3 ), or Part B (Curved trestle) Steps 1-5 (Pages 4-5). The abutments are optional. They may be timber, stone, or omitted entirely. Place the track in position on the trestle and mark on the rails and ties where the top caps are located. Also mark where the ends of the trestle are located. Page 6

7 PART C - BUILDING PILE BENT, BALLASTED DECK TRESTLE (cont'd) 6 Transfer bent locations from track to aluminum sheet 7 Approximately 5.5", typical Use spacers to maintain consistency Trace outline of strips Outlines should intersect at bent locations 8 Draw in the bent locations on the sheet Place the track on a sheet of 1/8" thick aluminum. Position the track so the clearances to the edges are somewhat equal and at least 1". Transfer the top cap locations from the rail to the aluminum sheet. Set the track aside and mark the bent locations on the aluminum. Plan view Place 1/2" x 1/2" stock alongside the track. Line the material up so the outside dimension is about 5.5" and the clearance between the material and the ties varies from 1/4" to 1/2". Use 1/2" x 1/2" spacers to help align the material. The spacing does not have to be precise, but should be pleasing to the eye. Trace around the outside of the 1/2" x 1/2" strips. Make sure the outline segments intersect at the top cap locations. 9 Cut mitered section of 1/2" x 1/2" material for the side walls Band saw or Sawzall Cut the ballast deck out of the aluminum sheet with a bandsaw or Sawzall. You may need to go over the edges with a belt sander to clean them up. Cut pieces of 1/2" x 1/2" stock for the ballast wall. Miter the ends at the top cap locations. Cut separate pieces for each section, including the straight sections. Leave gaps at the ends for drainage Attach deck to trestle support with #8 or #10 flat head wood screws Mark locations for deck attachment screws Countersink clearance hole Screw the ballast walls in place with #4 x 1/2" metal screws. Use two screws per section. Drill 1/8" diameter clearance holes and countersink them from the bottom. Attach the decking to the trestle support with a flat head wood screw. Countersink this hole. Mark the decking where screws will attach it to the top caps. Page 7

8 PART C - BUILDING PILE BENT, BALLASTED DECK TRESTLE (cont'd) 12 Attach decking to top caps 13 Ballast With the decking removed, drill and countersink two 1/8" holes at each top cap location. Be sure to miss the nails in the top cap. Attach the decking to the top caps with #4 x 1/2" flathead sheet metal screws. Lay the track in place and install ballast. PART D - BUILDING A FRAME BENT, BALLASTED OR OPEN DECK, TRESTLE 1 Track sets the path of the trestle Built in Place Trestle, Curved or Straight 2 2" x 4" Ballast/roadbed retainer 2" x 4" Trestle support Lay track in place. Install the 2" x 4" ballast retainers as shown in Part A, Steps 1 and 2 (Page 1). Install and locate the 2" x 4" trestle supports as shown in Part A, Step 3 (open deck, Page 2) or Part C, Step 3 (ballasted deck, Page 6). 3 4 Trestle Guide Build the trestle guide as shown in Part B, Steps 2-4 (Page 4). Measure the bent sizes as shown in Part A, Step 7 (Page 2). Build the frame bents according to the Trestle Bent Instructions. Build them about 1" shorter than required to reach the terrain. 2" x 6" Lumber footings Attach 2" x 6" pieces of treated lumber to the sills of the bents. These will serve as footings for the bents. Page 8

9 PART D - BUILDING A FRAME BENT, BALLASTED OR OPEN DECK TRESTLE (cont'd) 5 6 Rubber bands hold alignment Abutments are optional Dig out holes for the footings as in Part A, Steps 11 and 12 (Page 3). Position the bent assemblies in the holes at their approximate location. 7a 7b Use a torpedo level to keep bents vertical Position the trestle guide on the trestle support and attach it temporarily. Suspend the bent assemblies from the trestle guide with rubber bands. The rubber bands may not be able to hold the full weight of the bent assembly. In this case, use the rubber bands merely to help align the top cap with the trestle guide while the support for the footings is adjusted. Fill in the holes around the footings. OR OPEN DECK - Install braces, stringers, and track as in Part A, Steps (straight track, Pages 3-4) or Part B, Steps 5-8 (curved track, Page 5). BALLASTED DECK - Install braces, decking, and track as in Part C, Steps 4-13 (Pages 6-8). PART E - BUILDING A BALLASTED DECK PILE BENT TRESTLE ASSEMBLY Benchtop, Curved or Straight The basic idea of the trestle assembly is that you build the trestle in the shop and install it in the layout in one piece. There are many advantages to using a trestle assembly on your outdoor layout. 1. You can store the trestle indoors during harsh weather. 2. Most of the construction can be done on a workbench, so you can work on the trestle during harsh weather. 3. It is easier to repair a trestle on a workbench than in place on the layout. The author extends his thanks to the Outdoor Railroading crew at Thanksgiving Point, Utah. They shared this technique with me in The pile bent trestle assembly works best on long trestles where most of the bents are the same helght. The base of a trestle assembly often rests in gravel, so there is a limit on how steep the sides of the canyon can be. Page 9

10 PART E - BUILDING A BALLASTED DECK PILE BENT TRESTLE ASSEMBLY (cont'd) 1 2 Make legs longer than your measurements. 1/8" Trestle guide Trestle support Ballast retainer Set the ballast retainer, install the trestle supports, and cut the trestle guide as shown in Part B, Steps 1-4 (Page 4). For the ballasted deck, position the trestle support 1/8" below the ballast retainer. Trestle guide 3 4 Drill pilot holes for nails Measure the bent heights and build the bents as shown in Part A, Steps 8 and 9 (Pages 2 and 3). Make the bents about 3 inches taller than required. Tap nails in to mark bent locations Trace the outline of the trestle guide Approx. 12" both ends Mark bent locations on the side Transfer bent locations from trestle guide Turn upside down on plywood or MDF Mark the bent locations on the sides of the trestle guide. Drill clearance holes for pilot nails at the center locations of the bents. Turn the guide over on a piece of plywood or similar material, like MDF. Allow about 12" clearance at the ends of the guide. 1/2" x 1/2" 5 6 Bent locations Mark the bent locations on the plywood by tapping in the nails and transferring the marks on the sides of the trestle guide. Trace the outline of the trestle guide. Remove the trestle guide and re-mark the bent locations. Clamp supports Rigidly attach braces Paper spacer.148" x.443" Brace stock 1/2" x 1/2" (2x) Place the bents upside down on the plywood. Nail pieces of 1/2" x 1/2" stock beside the top caps as a registration fixture. Place a double thickness of typing paper between the top caps and the registration fixtures. Nail scraps of brace stock at the ends of the top caps. Use a torpedo level to keep bents vertical Build two uprights from scrap 2" x 4" and plywood. Screw them to the plywood at the ends of the fixture. Clamp braces to the uprights and the trestle bents. Use a torpedo level to make sure they are vertical. Rigidly attach braces between the legs. Page 10

11 PART E - BUILDING A BALLASTED DECK PILE BENT TRESTLE ASSEMBLY (cont'd) 7 8 Build ballasted deck assembly Install the diagonal bracing and girts. Install bracing 9 Attach deck assembly to trestle assembly 10 Remove the trestle from the fixture. Build the ballasted deck assembly as described in Part C, Steps 5-10 (Pages 6-7). Prepare bed to install trestle Provide drainage Attach the deck assembly to the top caps as described in Part C, Step 12 (Page 8). Attach deck to trestle supports Scoop out the earth where the trestle will be mounted and prepare a bed for the gravel. Line the bed with ultraviolet resistant plastic sheet and provide drainage. Do not put the gravel in the bed yet. Install track and ballast Bury base of trestle in large gravel Mount the trestle assembly on the trestle supports as in Part C, Step 11 (Page 7). Suspend the legs into the bed. Place 1" to 2" gravel in the bed around the legs of the trestle. Install the track and place ballast around it. Page 11

12 PART F - BUILDING AN OPEN DECK PILE BENT TRESTLE ASSEMBLY Benchtop, Curved or Straight Open deck - track is not shown Timber abutments are required This trestle is like the one presented in Part E except that it has an open deck instead of a ballasted deck. The basic idea of the trestle assembly is that you build the trestle in the shop and install it in the layout in one piece. There are many advantages to using a trestle assembly on your outdoor layout. 1. You can store the trestle indoors during harsh weather. 2. Most of the construction can be done on a workbench, so you can work on the trestle during harsh weather. 3. It is easier to repair a trestle assembly than a trestle that is build into the terrain. The author extends his thanks to the Outdoor Railroading crew at Thanksgiving Point, Utah. They shared this technique with me in The pile bent trestle assembly works best on long trestles where most of the bents are the same helght. The base of a trestle assembly often rests in gravel, so there is a limit on how steep the sides of the canyon can be. Trestle guide Ballast retainer Trestle support Set the ballast retainer, install the trestle supports, and cut the trestle guide as shown in Part A, Steps 1-4 (Pages 1 and 2). For the open deck, position the trestle support.667" (the height of the stringer material) below the ballast retainer. 3 Make legs longer than your measurements. Use stringer material to set height of trestle support Build two trestle bent type timber abutments as shown in Part A, Steps 5-6 (Page 2). DO NOT INSTALL THEM ON THE TRESTLE SUPPORTS. Set them aside for later. THESE ABUTMENTS ARE REQUIRED FOR THIS TRESTLE. 4 Include locations for abutments Horizontal member will help stabilize trestle later Measure the bent heights and build the bents as described in Part A, Steps 8 and 9 (Pages 2 and 3). Make the bents about 3 inches taller than required. Place a piece of leg stock horizontally at the bottoms of the bents..148" x.443" 1/2" x 1/2" (2x) Build the trestle construction fixture as shown in Part E, Steps 3-5 (Page 10). Add locations for the two abutments. Page 12

13 PART F - BUILDING AN OPEN DECK PILE BENT TRESTLE ASSEMBLY (cont'd) Clamp supports 5 Keep bents vertical with a torpedo level 6 Rigidly attach braces Use rubber bands to hold pieces in place Build two uprights from scrap 2" x 4"s and plywood. Screw them to the plywood at the ends of the fixture. Clamp braces to the uprights and the trestle bents. Use a torpedo level to make sure they are vertical. Rigidly attach braces between the legs. 7 Open deck stringers Install the diagonal bracing and girts. Use the maximum bracing on the abutments. 8 Abutments and bracing provide structure to support stringers Remove the trestle from the fixture. Turn it over. Build and install the open deck assembly as described in Part B, Steps 6-8 (Page 5). Prepare a bed to mount the trestle as shown in Part E, Steps (Page 11). Place the trestle assembly in the layout. Attach the stringers to the trestle support. Place the legs and braces in the gravel bed. Install the track. Anchor the track if necessary as described in Part A, Step 16 (Page 4). Place 1" to 2" gravel in the bed around the legs of the trestle. PART G - BUILDING AN OPEN DECK FRAME BENT TRESTLE ASSEMBLY Benchtop, Curved or Straight If you are unsure what trestle configuration to build, it is highly recommended you build this one. 1. You are able to make full use of all the capabilities of the Black Bear Trestle Jig. 2. The completed assembly is very sturdy and easy to transport and remove from the layout. 3. Most of the work can be completed indoors at a workbench. Page 13

14 PART G - BUILDING AN OPEN DECK FRAME BENT TRESTLE ASSEMBLY (cont'd) 1 2 Trestle guide Ballast retainer Use stringer material to set height of trestle support Set the ballast retainer, install the trestle supports, and cut the trestle guide as shown in Part A, Steps 1-4 (Pages 1 and 2). For an open deck, position the trestle support.667" (the height of the stringer material) below the ballast retainer /2" x 1-1/2" Footing Trestle support Height of bent Build two trestle bent type timber abutments as shown in Part A, Steps 5-6 (Page 2). DO NOT INSTALL THEM ON THE TRESTLE SUPPORTS. Set them aside for later. THESE ABUTMENTS ARE REQUIRED FOR THIS TRESTLE. Platform Form the area where the trestle will be mounted. Use treated wood, bricks, gravel, or concrete to build platforms about 1/4" below where the trestle footings will be. Locate the platforms under the bent locations marked on the trestle guide. Include locations 5 6 for abutments Measure the bent heights as described in Part A, Step 8 (Page 2). Use the Trestle Bent Instructions to build the bents you need. Check with torpedo level Hold bents vertical.148" x.443" Brace stock 1/2" x 1/2" (2x) Build the trestle construction fixture as shown in Part E, Steps 3-5 (Page 10). Add locations for the two abutments. Use rubber bands in some places to hold bents upright Build two uprights from scrap 2" x 4"s and plywood. Screw them to the plywood at the ends of the fixture. Clamp braces to the uprights and the trestle bents. Use a torpedo level to make sure they are vertical. Rigidly attach braces between the legs. Page 14

15 PART G - BUILDING AN OPEN DECK FRAME BENT TRESTLE ASSEMBLY (cont'd) 7 8 Install the diagonal bracing and girts. 9 Attach stringers to trestle support 10 Remove the trestle assembly from the fixture and turn it over. Install the open deck as described in Part B, Steps 6-8 (Page 5). In this case, the work can be done on a workbench. Footing Install the trestle on the trestle supports Shim up footings with wedges and spacers until they contact trestle sills Build and install trestle footings from treated lumber or concrete. Center the footings under the trestle bent sills. Shim up the footings so they contact the bottoms of the sills Footing Anchor the footings with caulk or grout. Caulk or grout Install the track. If necessary, anchor it to the stringers as shown in Part A, Step 16 (Page 4). Cover the platforms and bases of the footings with sod or gravel. Page 15

16 PART H - BUILDING A BALLASTED DECK FRAME BENT TRESTLE ASSEMBLY Benchtop, Curved or Straight 1 2 Trestle guide Ballast retainer Trestle support.125" Set the ballast retainer, install the trestle supports, and cut the trestle guide as shown in Part B, Steps 1-4 (Page 4). For the ballasted deck, position the trestle support 1/8" below the ballast retainer. 3 4 Build a frame bent trestle upside down as shown in Part G, Steps 3-7 (Pages 14-15). The timber abutments are optional with this trestle. Build the decking as shown in Part C, Steps 5-10 (Pages 6-7). Locate, drill, and countersink all the holes for attaching the decking to the trestle top caps and the trestle supports as shown in Part C, Steps 11 and 12 (Page 7). Attach the decking to the trestle assembly as shown in Part C, Steps 11 and 12 (Page 7-8). 5 Drop the trestle assembly into place and attach the decking to the trestle supports as shown in Part C, Step 11 (Page 7). 6 Install the trestle footings as shown in Part G, Steps 9-11 (Page 15). Install the track and ballast. Page 16