Quick!? Need to have you show how that's done!
Not sure but not a lot. The Baltimore Pike was built early 1800s but the alignment might have been a little bit upstream as appaerntly there was a bridge. I think we're seeing reinfocement to spread the loads under the track bed and street.
The big sewer should be further down. The storm drains along the streets have their own sewer. That might be the brick arch we see in the second photo. I remember the drawings for side street connections show a "egg shaped" cross section to the sewer - and its closer to the sidewalk. Making it narrower at the bottom keeps velocity up. Kindof cool someone thought about that.
