The construction of the upper chord of the bridge was also poor. This chord consisted of five I-beams running in parallel. Having all five members end at panel joints actually weakened a bridge, so Howe trusses were built so that three ended at one panel connection and the other two at the next panel connection. As with the connection between diagonals and angle blocks, it was critical that there be no space between the I-beams and the lugs on top of the angle block because these lugs transferred axial forces to the next member. Space between the member and lug would reduce the effectiveness of this transfer and introduce shear stress to the lug. The problems with camber led to members of the chords being shortened and the lugs being shaved down, actions which introduced space between the lugs and the chord members. Construction workers used metal shims to fill the space between the lug and the chord members until a tight fit was achieved. Friction alone, rather than an active connection such as a yoke or bolt, kept the shims in place. For some years prior to the disaster, locomotive engineers reported hearing "snapping sounds" as their trains crossed the Ashtabula Bridge. This indicates that some shims had come loose and fallen off, reintroducing space between the chord members and angle block vertical lugs. This allowed members of the chord to thrust suddenly against the lugs, inducing even more metal fatigue. There is also an indication in the construction record that several chord members were misaligned. Even if their bearings had been flat, they would not have met the lugs completely. This, too, would have created uneven loading and worsened metal fatigue.