As well, two huge concrete trenches had been dug on each bank.
Each position was surrounded by several ditches, or concrete trenches, with shelters and observation cupolas.
The runoff was collected in the four sumps that were connected by open concrete trenches.
Here, a concrete trench is formed in the ground using wood forms, reinforcing bar and manual labor.
The installation consists of a 340-ton boulder affixed above a concrete trench through which visitors may walk.
The work comprises a 21.5-foot tall boulder mounted on the walls of a 456-long concrete trench, surrounded by 2.5 acres of compressed decomposed granite.
Completion of the concrete trench and the final securing of the boulder took an additional three months.
However, the bumper cars were removed following Cedar Fair's purchase of the park in 1993, leaving the tunnel that began the ride as an open concrete trench.
The route passes through a concrete trench and abruptly curves to the southeast as it passes beneath Victoria Avenue, with which there is a simple interchange.
The cadet in charge led them up to the surface into a concrete trench about four feet deep.