Why is shear not checked for vertically laminated wood bridge decks?

[MagicFarmer]

Good afternoon,

I'm plugging away on the design of a nail-laminated wood bridge deck today and have come across two clauses that state that shear need not be checked for vertically laminated wood decks.

From CSA S6:

"Cl.5.5.8 Transverse wood deck
Only the transverse moment need be analyzed for bridges incorporating laminated wood decks spanning transversely between longitudinal girders or stringers."

"Cl. 9.7.5 Vertically laminated decks
Shear shall be neglected in vertically laminated decks."

At first, I thought that I must have misinterpreted the clauses, but, upon reviewing design examples in the Ontario Wood Bridge Reference Guide, i see that they do not carry out any shear checks on the deck.

Could someone please explain why this would be the case?

The code has a load sharing factor for both moment and shear... and yet shear is ignored? In the literature for nail laminated timber for buildings, there are shear calculations completed (although it is stated that shear rarely governs).

Thanks in advance for any light shed on this.