Track is a term I might not shoulda used, but I’m used to these pieces having multiple uses. Track literally that, a bed of staggered timber supported by low cribs, placed to roll a bridge or a building on –

Needles as Jim suggests are the support matrix that the crib towers carry, you might crib up to floor level and support all the joists with a bed of timber needles, then crib on up above to catch the plates with some steel needles, no two jobs demand the same shoring plan, that’s half the fun in the rigging end of this game.

It’s also good practice to tie towers in tall spaces together, with needles placed solely for that reason, say anything that is gonna demand a few feet above ten – These are also useful for scampering from jacking station to jacking station.

A few 8’s and 20’s would come in useful also.