The Dinky, Princeton Shuttle, or the PJ&B (Princeton Junction & Back) is the shortest regularly scheduled Commuter Rail/mainline Railroad service in the United States. The 2.7 mile branch line connects the Northeast Corridor's Princeton Junction at West Windsor's Station to the Princeton Station on the Princeton University Campus in about five minutes. The Dinky runs about two roundtrips per hour (both weekdays and weekends) to connect with almost all arriving Northeast Corridor Trains. The schedule is about every half-hour but departures are timed to correspond to the non-consistent times of the connecting trains; during rush hour there are few times it makes two trips in the same direction within twenty minutes.
The Dinky normally runs with one or two Arrow MU cars staffed by both an engineer and a conductor who does collect tickets during the short ride. Generally these are some of the NJ Transit employees with the highest seniority, running the Dinky is a desired gig. In 2012 the extra charge for a ride on the Dinky was $2.75 for just a single ride, (such as connecting from Amtrak), in 2024 this has gone up to $3.45. Fares to Princeton are generally about $1.75 more (to Newark/New York/the Airport as low as $1.25 to Hamilton, as high as $2 from New Brunswick) on thru continuous tickets requiring the connection. These extra fares seem quite high considering the very short length of the branch. As of 2024 the differences are $20.40 one-way, $18.40 NYC, $2.55 versus $4.30, $8.90 versus $7.30.
The Dinky has been shuttling on its little branch line continuously since May 29, 1865. The single branch line was built to connect Princeton to the then new and present-day alignment of the now called Northeast Corridor by the Camden and Amboy Rail Road and Transportation Company which was abandoning the route it originally used since 1839 following the Delaware and Raritan Canal which stopped much closer to downtown Princeton. The name Dinky then began being applied to the shuttle for the steam dummy car, a single self-propelled steam engine/passenger car, used for service. The Pennsylvania Railroad took over the NEC along with the Dinky in 1871. The branch line was electrified in the 1936 at the same time as the mainline.
The station location on campus has changed multiple three times since the line’s opening in 1865, as the campus developed, and trains were pushed farther and farther south on campus to avoid the railroad interrupting activity on the center of campus. In 1918 the original 3 mile line was pushed back from in front of Blair Hall to a new station on University Place, the line remained at this location until it was moved to a temporary location on the outskirts of campus in 2013 (sadly not visited) and then became 460 feet shorter at its current very modern station in 2014 as part of the $330 million Arts and Transit Project. This project again brought the Dinky farther from the center of campus and more to the edge of campus reducing ridership by 20 percent from 2012 to 2017.
Train service on the Dinky has deteriorated a lot since the lines relocation, it was fully suspended from October 2018 through May 2019 due to the lack of railcars for the installation of positive train control and an engineer shortage, although due to the Dinky’s uniquely short length with only one train operating on the line at the time, PTC wasn’t installed on the branch itself.
As of 2024 the future of the Dinky is uncertain. New Jersey Transit hasn’t purchased any real single-level EMUs. It has purchased new MultiLevel III EMUs, but these EMU cars lack cabs in the powered railcars and are designed to ride between two unpowered cars to operate as a minimum 3 car train. This train length appears to be much too long for the Dinky. Various proposals have been made to pave over the ROW for the creation of a transitway or the conversation of the Dinky to be part of a larger Princeton Light Rail system or paving over the tracks for a combined busway/light rail system.