The bridge being from Flora Vista would make more sense than Cedar Hill. Bridge 485B east of Flora Vista is shown on the valuation map as being composed of 5 different spans. In later years it was probably replaced by 2 thru truss spans with one still there today. The photo below shows some piers east of the remaning span that could have supported the bridge in question as the yellow line works out to be just shy of 170'. The extra set of piers might be from an earlier configuration.
The configuration as listed on the val map from west to east:
1 panel trestle 24'
Thru Howe truss 126'
2 panel trestle 54'
Thru Howe truss 127'
2 panel trestle 38'
Dave