That may be part of the fire-fighting equipment

It got that rep when a Chicago alderman T-boned it and they hushed it up, blaming the whole resultant crash on the Dymaxion

AKA the Dollar Nineteen

You realize the height of the bridge is limited due to the two adjacent airports requiring airspace. Yet, the underside need to be high enough to let shipping pass underneath, with the height more towards the northern side due to the river channel.

Instrumentation rockets shot at varying intervals, measuring temperature and pressure. Identical to weather rockets of the day