At its peak, the Providence, Warren & Bristol Railroad (owned by the New Haven Railroad) was an electrified commuter rail line, seeing about 100 trains daily. In 1937, the company switched over to gas-electric cars. Ultimately, passenger service was completely discontinued by 1938 due to irreparable damage done by a hurricane that year, rendering the PW&B a freight-only railroad.
The PW&B's northern terminus was at India Point Park, where it branched from the New Haven Railroad (now AMTRAK's Northeast Corridor); this junction formed a wye on the east side of the Seekonk River, with the southern leg leading to PW&B. From there, its line ran over to East Providence, then through Riverside, Barrington, and Warren, with double track between Providence and Warren, a distance of 10 miles. From Warren, the line split into two single-track branches, one going east to Fall River, MA (10 miles) via the Slades Ferry swing bridge, the other to the railroad's southern terminus at Bristol, RI (4.5 miles).
Providence's Union Station was located just west of the PW&B's northern terminus. Attempts were made to run full size freight cars over the trolley tracks to Union Station, which resulted in frequent derailments. This spurred the construction of a massive lift bridge, a mile-long tunnel under East Providence, and a viaduct, in that order, to facilitate freight cars. Both the bridge and the tunnel were abandoned and the viaduct demolished when the Northeast Corridor was re-routed to facilitate some remodeling of the downtown area in Providence. The lift bridge is still in place, and the tunnel portals have since been sealed.
One interesting technical aspect of the electrification was the power system; the power house was located approximately at the center of the system, just north of the station location by a few blocks; the foundation remains for the boilers are just about 50 feet or so off the right side of the bike trail heading north out of Warren. The overhead was a standard 600 Volt DC trolley system (single-wire, not catenary, the cars used trolley poles). To handle peak rush-hour power demands, two battery stations were built close to the Providence & Fall River ends of the line; off-peak, the batteries were "float-charged" by the power plant in Warren. During rush hour periods, the battery stations would pick up some of the load, easing the burden on the powerhouse. Amazingly, the battery house on the Fall River end, which was located just a few hundred feet west of the Slades Ferry Bridge, in Swansea MA., is still in existence as a derelict building; it is believed to have been a machine shop (not railroad-related) for a while after the electrification was abandoned.
The Slades Ferry swing bridge on the Falls River branch was a double-decker affair with automobile traffic running inside the truss, and trains running atop. The bridge was destroyed when a passing ship attempted to navigate past the swing section and collided with it. This in effect ended PW&B passenger service to Falls River, as the bridge's railroad part was abandoned. The bridge was subsequently bought by the state of Massachusetts as a highway bridge, with a lift drawbridge replacing the original swing section. The completion of the much higher Braga bridge (I-195) rendered the Slades Ferry bridge a hazard to navigation and was demolished around 1965. Only the end abutments of the bridge exist today, along with a lone rusty semaphore mast that marks the line's path.
Rhode Island's East Bay Bike Path makes use of the PW&B's former right-of-way. Where the right-of-way was double-tracked, the bike path occupies one of the main lines; the parallel main line and its tracks is often visible running alongside. The track passes the original station in Riverside, which now houses a tanning salon.
The railroad tracks just north of the PW&B's northern terminus, which was owned by the Providence & Worcester, was recently abandoned and removed to make way for the reconstruction of the I-195 George Washington bridge, which flies over the line.
Thanks to Tom Lapointe for contributing information about this route.