From The Collaborative International Dictionary of English v.0.48 :
Trestlework \Tres"tle*work`\, n.
A viaduct, pier, scaffold, or the like, resting on trestles
connected together.
[1913 Webster]
From WordNet (r) 3.0 (2006) :
trestlework
n 1: a supporting structure composed of a system of connected
trestles; for a bridge or pier or scaffold e.g.