one-way bridge lanes

As it stands, even the 4 lane bridges will not allow excavators above the small class to access them. Adding the option to set multiple lanes to a single direction so that the larger excavator's to occupy multiple lanes to traverse the bridges would be a HUGE QoL improvement.

While mega trucks traveling on bridges would be an amazing QoL improvement for the game, however realistically moving a 1.9 million pound mega excavator like the Hitachi ex8000 over a bridge is just impossible.
So in game, the only way to get an excavator to an island or atop a mountain is to build a bridge (or use amphibious trucks) then build a vehicle depot at the destination. Then just teleport the excavators to the depot using the recover button.

Blade, i get that, and currently that's what i do, but on my main island I use t2 and amphib. excavators and trucks to terraform, in early game getting those trucks from higher levels to lower still requires either multiple depots OR terraforming inclines (which defeats the purpose of bridges).
I am also open to expanding the idea from other's input! so thank you for the comment.

Alternatively, provide some ship that can move vehicles across the sea

To justify the impossibility of heavy equipment crossing bridges, a new parameter should be introduced: the load-bearing capacity of the structure. Quarries should have their own super-reinforced bridges, indicating the ability of quarry trucks to pass through.
If the developers really want to restrict the movement of super-heavy vehicles on bridges, then why can't lighter, wider vehicles cross them?
Why not allow excavators to travel on lowboys and railway platforms? Teleportation for unity also doesn't look very good from this perspective.