As you drive across America’s Interstate Highway System you may notice certain special off-ramps that only large cargo trailers take. These weigh-stations are used by the states to check permits, as well as determine whether a truck is within weight limits based on how heavy it is. The truck simply drives onto a large platform with a scale under it, sometimes stopping, sometimes not.  The scale measures the truck’s weight and if all is well the truck goes on its way.  It’s all very quick and easy. But it has roots in an earlier transportation system: America’s canals.

This is the Erie Canal Museum, located on Erie Boulevard in Syracuse, NY. Today the building borders one of Syracuse’s busiest streets but for decades that street was a waterway, the Erie Canal, and at one time was the busiest cargo thoroughfare in the country.

When it opened in 1825 the Erie Canal was the largest public works project in the world and it wasn’t cheap. To pay for it, the State of New York levied tolls on the canal boats for its use. The tolls were determined by the weight of a canal boat’s cargo (and also the type of cargo, but that’s a discussion for another day), but how best to determine what the cargo weighed?

The first idea was the hydrostatic method, and it worked like this: On the edge of the canal would be a separate water-filled chamber with watertight doors at either side. Before a canal boat would enter it, a weighmaster would mark the water level. After the boat entered and the doors were closed the level would be marked again. The difference between the two levels (which was the amount of water the boat displaced and thus, EUREKA!, its weight) was matched to a dollar amount. The hydrostatic method worked, but canal workers, most of whom never received a formal education, were distrustful of it.

A new system was devised and implemented with the building of weighlock building like the one at Syracuse. A canal boat would sail into the chamber where the water would be drained out through an underground sluice. As the water level lowered the boat would settle on a wooden cradle which was suspended by a system of iron rods. Inside the weighmaster’s office a scale would read the total weight of the boat, which would be compared to the boat’s registered empty weight. The difference was the weight of the cargo and a toll would be applied.  Weighmasters referenced a long complicated table to determine the toll based not only the cargo’s weight, but also what kind of cargo it was (salt, tools, produce, etc.).

The Syracuse Weighlock opened in 1850 and was one of seven weighlocks along the canal between Buffalo and Albany. Today it is the only one that remains. Tolls on the Canal were abolished in 1883 although the building remained as offices. Facing demolition, the building was saved in 1962 by a group of citizens who wished to preserve it. Today it contains the Erie Canal Museum, complete with full-size replica canal boats, fantastic exhibits about life along the canal, and details about the inner-workings of the weighlock. The canal itself has been moved south of Syracuse and where it used to run is today Erie Boulevard.

 

Sources

The Erie Canal Museum, Syracuse, NY.  http://eriecanalmuseum.org

Sheriff, Carol. The Artificial River. New York: Hill and Wang, 1996. Book.