Maybe site cast?? We do alot of “tilt-up” construction here. They cast a huge slab on the ground, let it cure, then stand it up for a wall. The beam could be done similarly at the site.
To whoever posted the pedestrian bridge collapse, I never did go find out if they determined poor design was the cause or shoddy materials and/or workmanship in construction, but typically Post tension concrete is pretty stable, I have drawn a few freeway bridges in earthquake prone California, that have performed well since.
Seems like I read afterwards that Cemex supplied the concrete and we had terrible 7 day break test results on their concrete here when I was inspecting post tension foundations years ago.
The equipment needed to cast this beam is quite substantial oh, it can’t be cast on site.