Two Lines Per Side
A double-truss bailey bridge uses two truss lines side by side on each side. A single-truss bridge has one load line per side. Every tonne goes through that one line. A double-truss bailey bridge splits the load into two lines. Force per line drops. The same panel, doubled side by side, doubles the section width. Bending capacity follows. We torque every connection between the two lines to the same figure. No guessing by feel.
How Load Divides
The point of double truss is not doubling steel. It is changing the load path. Traffic presses the deck. The deck presses the transom. Each end of the transom sits on one truss line. Both lines deflect together. If one line is stiffer, load drifts to it. We cut both lines from the same steel batch, same dies. Matched performance. Pin joints allow slight rotation. They release local stress before one line takes too much.
Assembly Sequence
Double-truss bailey bridge assembly adds one step over single truss: aligning the pair. Install two panels side by side on one side. Transom clamps lock both at once. Then the other side. Sway braces control the gap between the pair. Turnbuckles allow fine adjustment. Deck panels rest on transoms, not on the truss. Cantilever launching works. Double truss weighs more than single. Balance point must be calculated before pushing out.
Specifications
Truss lines: two per side
Panels per side: 2 rows × number of bays
Transom connection: one transom locks both rows
Sway brace: controls row spacing, adjustable
Span range: 24m to 45m+ (double truss, single story)
Load class: up to Auto-20 or Trailer-80 range
Deck width: 4.2m single lane / 7.35m double lane
Main steel: Q345B or Q355B
Pins: 30CrMnTi
Bolts: grade 8.8
Where It Goes
A double-truss bailey bridge fits projects that need span but not height. Double-story bridges add elevation. That means longer ramps and higher abutments. Double truss keeps single-story height. It widens the section instead. Deck level stays the same as single truss. A construction crossing over a thirty-metre river: single truss is soft, double story is overkill. Double truss sits right. Mining haul roads with constant heavy traffic: double truss spreads load across four lines. Pin hole wear slows down.
Contact
Jiangsu Jiuzhou Bridge Engineering Co., Ltd. Panels, pins, transom clamps, and sway braces made in-house. Double-truss configurations calculated by span and load. Send your figures. We will return a configuration sheet.
