Another path finding problem, probably related. The lorries seem extremely unwilling to “take a right to go left”, or a left to go right. See those pics:
On the first intersection, they will not take the right off-ramp, but rather change lanes (causing congestion) just beforehand and take the left ramp - there is no node there, and they change lanes all the same.
Same thing, with sides changed, on the second intersection - they will never take the left off-ramp, just change lanes in order to get the right (but quite wrong) ramp.