Milwaukee drawbridge gates

[AndyWS]

Have you seen the lights and gates activate? If so, how do the red beacons work? Do they flash alternately, or together?

Well, I was wrong about that. I saw the Juneau Ave. bridge open for a barge today, and the four beacon lights flashed together for each direction of traffic. The signals at the one to the north, on Knapp St., flashed alternately.

The four lantern gate lights on each gate stayed steady, and the motor bells rang slowly but steadily.

[AndyWS]

Well, after personally seeing only one bridge opening the first 3+ months I've lived in Milwaukee, I've now seen two in the last two days. On my way home from class this morning I had to stop off at the hardware store, and when I was on my way from there to the bus stop the Knapp St. bridge signals activated. That bridge has B&B gates with five gate lights per gate. The beacon signals flash alternately there, and the gate lights alternate left-left-right-right in pairs, with the tip light on steady.

Where O = on, - = off:

O-O-O
-O-OO

That bridge is not a drawbridge, but a lift bridge. The middle section raises straight up. The river traffic was the same as yesterday - a barge with a tugboat pushing it, going south. Because the activation cycle is long (the exit gates don't start to lower until about 10 seconds after the entrance gates fully lower, to give traffic time to clear the length of the bridge) and only after the exit gates are fully lowered does the bridge section start to (slowly) lower, and the barges are slow, the activation takes about as long as a railroad crossing during a long freight train.

[TommyBNSF]

Here is one of them in action. http://www.youtube.com/watch?v=IiJuxf9_2kc