STONE SLEEPERS OF THE CAMDEN AND AMBOY RAILROAD, NEW JERSEY

About 100,000 stone sleepers supported the rails of the Camden and Amboy Railroad (C&A) constructed during 1831-32 between the Delaware River and Raritan Bay in New Jersey. Sleepers are stone blocks with average dimensions of 20x20x10 inches. Sleepers of West Jersey were quarried locally and consist of Lower Paleozoic and Pre-Cambrian gneiss and quartzite of the Trenton Prong, Triassic Stockton Sandstone of the Newark Basin, and Cenozoic conglomerate of the New Jersey Coastal Plain. Sleepers of East Jersey quarried locally include: Stockton Sandstone and gneiss and granites from Staten Island, and both sides of the lower Hudson River. Sleepers imported to East Jersey consist of Inwood Marble, quarried by inmates at Sing Sing Prison in Ossining NY; Cape Ann Granite from just north of Boston; and metamorphic rocks of uncertain provenance but likely from southern New England.

During C&A construction, sleepers were spaced at 3.2 ft. intervals. Five sleepers supported each 16 ft. iron rail manufactured in Great Britain. Most sleepers have 2 spike holes to secure the rail. Sleepers under the joint between two rails have four spike holes. Many sleepers have a 9 x 14 inch chiseled area on the upper surfaces for the placement of a black locust planks used to level the rail, prevent abrasion of the iron rail, and cushion the train ride. Quarry marks include fine and coarse pin and feather features and pry bar marks. Single letters chisels on the top of about 20 sleepers may be laborer’s marks for payment.

Sleepers were laid in beds of hand crushed gravel size (~2 inch) ballast. Ballast rock type is generally the same as the sleepers. In central parts of NJ, much of the ballast is composed of hand crushed field stone of formerly well rounded cobbles of quartzite.

Original retaining walls along the Bordentown Ditch are predominately blocks of Stockton Sandstone with a lesser number of blocks of gneiss, schist, quartzite, and diabase. Abutments for four original carriage bridges and the former trestle bridge over Crosswicks Creek are composed of Stockton Sandstone blocks.

Many sleepers have been repurposed for erosion control on the banks of the tidal Delaware River and smaller creeks, as retaining walls to reduce landslides, as monument foundations, and as cityscapes.