On the Newton side, it was possible until recently to walk from one bridge to the other using an underpass below the MBTA Framingham line. Because of the poor condition of the underpass, the MBTA closed off access to it in 2016. (See 2017 photos.)
If the underpass is restored and the downstream bridge rebuilt, it will be possible to walk a loop trail beginning at Charles Street and Riverside Road in Newton, crossing one bridge into Weston, and returning to Newton on the other bridge. Plans for construction of The Station at Riverside mention the "potential" for walkways connecting the development to Riverside Park.