It became an important feeder line for the Lehigh Valley Railroad 's join to the Central Railroad of New Jersey , [ 1 ] which was constructed into Phillipsburg, New Jersey , at about the same time.
The Trenton- Lambertville section opened on February 6, , eventually reaching Belvidere on November 5, For much of the late 19th century and early 20th century the railroad line proved vitally useful. By the s, steam locomotives had been replaced with diesel operated self-propelled doodlebugs as a cost-saving measure resulting from dwindling patronage.
In August , flood waters from the Delaware River caused by Hurricane Diane washed out portions of the line north of Belvidere near where the right-of-way crosses modern-day US Route 46 , although the line still remains active south of this point to serve the Hoffmann-LaRoche pharmaceutical plant. North of where the plant is now to the junction at Manunka Chunk, the line was subsequently removed in late Trains began operating between Flemington and Lambertville by May 16, PC remnants were absorbed by Conrail in April , which treated the Bel-Del as a dispensable secondary line.
The main priority freight trains were rerouted to other lines. With little industry remaining between Trenton and Lambertville, Conrail had little use for the line. Though the south end of line passed within a few hundred yards from the central business district and state capitol complex in Trenton, no official interest in taking advantage of the line's passenger potential was raised. While the Trenton-Lambertville segment was not included in their system, Conrail retained the rest of the line from Lambertville to Belvidere, renaming it their Delaware Secondary.
Track removal began in the summer of and ended in the spring of In those three years Conrail dismantled approximately 31 miles of the line. Freight service was non-existent by the late s. Service trains operated over the Ringoes-Lambertville portion on a seldom basis until The line south of Carpentersville was soon after closed to Riegelsville in when another paper plant decided to not continue using rail service.
