Greenfield Bridge Over I-96

**softailrider** · August-05-22, 04:30 PM

Anybody ever notice that when you're stopped at that light you can feel a discernable shake to that bridge? I've noticed it for years, but it seems much more noticeable now. Not my imagination either, had somebody in the car today and they found it alarming.

**Zacha341** · August-05-22, 05:59 PM

^ Absolutely. I literally bounces when full up of cars and trucks.

**Lowell** · August-05-22, 10:40 PM

I’ll third that observation. Should it collapse we would hear the largest “I toldja so” in history.

**5939DT** · August-07-22, 09:51 PM

Drove under it today; it is quite a bit tall over I-96 and the railroad tracks, possibly contributing to its "flexibility"
Hopefully it won't end up like this:

https://archive.org/details/Tacoma-N...ridge_Collapse

**wolverine** · August-07-22, 10:38 PM

Steel beam bridges are efficient so they’ll vibrate under heavy traffic loads. It’s normal. Older girder bridges and some newer longer span steel bridges may not shake as much because the older plate girders are heavily stiffened and newer spans are deeper, but they cost a lot more.

However that pin and hanger design is obsolete in the US. Notice in streetview a non-rigid connection where the beam overhangs the pier. That may be where people notice the most movement.

They fail when not inspected or are heavily corroded and break. So far none recently that were catastrophic. The lakeshore drive bridge in Chicago had a beam break at a hangar connection causing the deck to drop maybe 6-8” but cars continued passing overhead until someone noticed

**Zacha341** · August-08-22, 10:57 AM

Who should be called [City of Detroit-wise] to report the shaking/ flexing?

**Honky Tonk** · August-08-22, 12:24 PM

Originally Posted by Zacha341

Who should be called [City of Detroit-wise] to report the shaking/ flexing?

The bridge falls under the State's responsibility.

**Sehv313** · August-08-22, 03:09 PM

Originally Posted by wolverine

Steel beam bridges are efficient so they’ll vibrate under heavy traffic loads. It’s normal. Older girder bridges and some newer longer span steel bridges may not shake as much because the older plate girders are heavily stiffened and newer spans are deeper, but they cost in the US.

Thanks! The perfect explanation.

**softailrider** · August-09-22, 09:32 AM

Originally Posted by wolverine

Steel beam bridges are efficient so they’ll vibrate under heavy traffic loads. It’s normal. Older girder bridges and some newer longer span steel bridges may not shake as much because the older plate girders are heavily stiffened and newer spans are deeper, but they cost a lot more.

However that pin and hanger design is obsolete in the US. Notice in streetview a non-rigid connection where the beam overhangs the pier. That may be where people notice the most movement.

They fail when not inspected or are heavily corroded and break. So far none recently that were catastrophic. The lakeshore drive bridge in Chicago had a beam break at a hangar connection causing the deck to drop maybe 6-8” but cars continued passing overhead until someone noticed

I didn’t know anything about that - it’s very informative.

**Gistok** · August-09-22, 12:44 PM

As far as "non-rigid" bridges and spans go, even the 170 ft. wide balcony at the Fox Theatre has a certain amount of "bounce" built into it.

Apparently back when Detroit architect C. Howard Crane designed/built the Fox Theatre in 1927-28, he made sure that it was not a rigid span.

When the Jonas Brothers used to come to Detroit for their concerts, their fans in the balcony used to jump up and down, with the balcony bouncing along with them... the brothers would test that bounce with a comment "still works". I'm sure this is no comfort to those who sat under the balcony at the time...