while of course possible-again it would have to assume Russian security incompetence to work. But the bridge was knocked out, just one lane of traffic. It would require a lot more to take the bridge out. The bridge is recent, they had supplies to their Navy base for years without it. but if it was forces working against Putin pushing him further into the war to go to total war-it might be a price to pay. But your theory is not without its merits, it IS possible. More likely if the driver was in on it and willing to die.