However, it seems to me to be a tactical mistake. In the city it is very difficult, if not impossible, to stop truckers from getting fuel, food, and bathrooms. They can create a public problem by blowing horns and blocking business.
On a bridge the police can easily keep anyone from supplying any of these items.
It is also likely to violate traffic laws leading to arrests, fines (possibly per day fines), higher insurance premiums, and loss of CDL due to the violations. Further, due to the linear nature it makes it easier to divert the trucks one at a time and impound them until fines are paid. You only need two tow trucks to clear the blockade. Any truck that appears to threaten violent action is easily stopped by putting a hole in the radiator.
It seems a tactical mistake to "line up" in a protest.