If we assume the ship was moving at approx. 30 mph, a 1 min. warning would mean that the cops got the alert while the ship was roughly a half-mile away from the bridge.

I have no idea what the actual speed of the ship was, but if it were moving down stream, I would think ~30 mph. would be a fair guesstimate to use for a point of reference.

{edit correction}. Mayor claims the ship was moving at 8 knots, ~9mph. If that is correct, then the cops did not get a warning till the ship was within 300 yards of the bridge.

If we assume the ship was moving at approx. 30 mph, a 1 min. warning would mean that the cops got the alert while the ship was roughly a half-mile away from the bridge.

I have no idea what the actual speed of the ship was, but if it were moving down stream, I would think ~30 mph. would be a fair guesstimate to use for a point of reference.