Delaware & Raritan Canal State Park
A natural waterway follows the contours of the land over which it flows, the depth of water varies, depending on the quantity and velocity of flow. To maintain the constant depth of water required for transportation, a canal is engineered as a series of flat levels or reservoirs of water connected by locks. Crucial elements in a canal system, lift locks hold back the water in the levels, accommodate for the natural elevation changes of the land, and allow boats to travel up and down between levels.
How a Lift Lock Operates:
A boat heading downstream enters the lock.
The lock gates are closed.
Wickets in the downstream gates are opened, water flows out, and the boat is lowered.
When water levels are equal, the downstream gates are opened, and the boat continues.
For a boat heading upstream, the procedure is reversed. Bypass channels were constructed around lift locks to allow canal water to continue downstream when locks were in use.
are of the same design, but do not function as true lift locks. These locks permit the passage of boats between a canal and a river or other body of water and accommodate for changes in water level or tide. The outlet locks on the D&R Canal are at Bordentown (Lock #1), New Brunswick (#14) and Lambertville.
are used in infrequently traveled areas and are similar to lift locks, but have only one pair of miter gates. The two structures in combination regulate the amount of water downstream and protect the canal from floods while allowing for the occasional passage of boats. The guard locks on the D&R Canal are at Bulls Island and Prallsville.
Water enters the Feeder Canal at Bulls Island at an elevation of about 67 feet above sea level. As it passes through the Lambertville lock it drops to about 55.7 feet, and remains at this level all the way to the Main Canal at Trenton. From this "summit" the Main Canal descended through seven locks to near sea level at Bordentown and in the other direction through seven more locks to near sea level at New Brunswick. The T-shaped section of canal defined by Lambertville Lock, Lock 7 in Trenton, and Lock 8 in Kingston served as a kind of reservoir for the Main Canal.
Locks used two kinds of gates: vertically hinged pairs of gates called miter gates
, and single gates, hinged at the bottom, referred to as drop gates
.Constructed to form a V-shape when closed, miter gates open upstream, and are kept closed by the pressure of the water. Miter gates are operated by pushing against long, heavy balance beams projecting from their hinged edges that counterbalance the weight of the gate. Drop gates are located at the upstream end of a lock. They open by dropping against the water flow to the floor of the canal, and are usually operated by a chain and wheel (windlass) system.
Delaware & Raritan Canal Lock History
1831-34: Canal was constructed with 15 lift locks (one on the Feeder and 15 on the Main Canal) and 2 guard locks. Main Canal locks were 24 feet wide and 110 feet long, much larger than locks on other canals. Original lock gates were miter gates with balance beams.1847-48:
Original masonry lock at Bordentown (#1) sank into its soft substrate and a replacement lock of stone-filled wooden crib construction was built a few feet to the west of the first one.1848:
Outlet lock was constructed at Lambertville for a cable ferry across the Delaware River. It was in operation until 1912-13.1849:
Head (upstream) gates of all locks were converted to drop gates. Today the gates are gone, replaced c.1944 by valve-operated concrete control gate structures at the head of each lock.1853:
Main Canal locks lengthened to 220 feet. Lock #5 in Trenton was eliminated and Lock #4 deepened to compensate.1866:
Second lock added in New Brunswick, making Lock #14 a double outlet lock.1932:
Canal ceased operation1936:
Trenton section of canal (Locks #3-7) filled in.1974:
Delaware & Raritan Canal State Park created.1980:
More than a mile of canal at the New Brunswick end, including Deep Lock (#13), was destroyed for NJ Highway 18.1998:
Last mile of the canal and Lock #14 restored and incorporated into Boyd Park, a City of New Brunswick facility.