It seems like the Illinois Tollway reconstruction plans omit the majority of bridges that cross over the tollways. On the Tri-State Tollway, many of the bridges weren't reconstructed. Signs warn that the road narrows at the overpass. It's probably a cost savings move and they figure that widening the tollways is the biggest priority, and that traffic can deal without a shoulder for a short time under a bridge.
That is because they cut corners
big time on the Tri-State rebuild. Frankly, I don't know how they got away with that. Plus, most of the bridges are from the original 1950's construction and will have to be replaced eventually. It appears they learned their lesson and all of the I-90 crossroad bridges between Rockford and I-294 (except the Railroad bridge west of Belvidere, the Randall Road bridge and possibly the twin U.S 20 crossroad bridges west of Belvidere) have been or are being rebuilt.
This was not the case with I90, almost all bridges had to be rebuilt to handle the extra lanes and wider shoulder (for future use). Most of the cross roads have been rebuilt with the current widening, while some are being done post widening due to scheduling and making sure proper detours can be provided. Some, if not almost all the bridges were done were in need of replacement anyways (original to the highway in the 50's) so I think this is just a staggering effect to make sure the higher traveled bridges and I90 work gets done on time, and they don't get behind on the bridges that were required to be rebuilt in order to get the extra lane in.
As for what was mentioned above, U.S 20 is receiving some funds for maintenance work on the bridges themselves, I'm wondering if they plan on doing a rebuild on the interchange at some point and would rather wait for that before replacing the bridge structure.
The ramp bridge at the U.S 20 interchange in Marengo was redone a decade ago, if that is what you are talking about. I am talking about the twin U.S 20 crossroad bridges west of Belvidere. For whatever reason, they were on the schedule (in the future construction bid schedule) for two brief periods of time the last two years, but were removed a while after. I was wondering if anyone knew why. I doubt they are planning to put an interchange their, since they just spent money on completing the Irene Road interchange nearby.
Good news is, it looks like the IL-23 interchange may be moving forward. In 2017, they have a contract to reconstruct the IL-23 bridge and roadway, which means they may be expanding the road in order to accommodate ramps.