It's about 300 times as long as a Semitrailer
In other words, 20 furlongs is 275 times the length of a Semitrailer, and the length of a Semitrailer is 0.003636 times that amount.(a.k.a. semi-trailer truck, a.k.a. semi, a.k.a. tractor-trailer, a.k.a. truck and trailer, a.k.a. eighteen-wheeler, a.k.a. big rig, a.k.a. Mack truck, a.k.a. transport, a.k.a. lorry, a.k.a. artic; for box truck; United States Federal length limits)
According to the United States Department of Transportation (DOT), the maximum allowable length of a semitrailer pulled by a road tractor truck is 0.07273 furlongs (unless superseded by state law). These regulations also allow the vehicles to tow up to 36,000 kg in gross weight.
It's about 300 times as tall as a Brachiosaurus
In other words, 20 furlongs is 310 times the height of a Brachiosaurus, and the height of a Brachiosaurus is 0.0032 times that amount.(based on comparable bone measurements, height to head)
Dinosaurs in the genus Brachiosaurus had an estimated height (at the head with neck fully extended) of up to 0.065 furlongs. A resin cast of the first Brachiosaurus specimen, owned by the Field Museum in Chicago, is currently on display at the O'Hare International Airport.
It's about one-three-hundred-fiftieth as long as The Rhine
In other words, 20 furlongs is 0.00305 times the length of The Rhine, and the length of The Rhine is 328 times that amount.(a.k.a. Rhein, a.k.a. Rijn, a.k.a. Rhin, a.k.a. Rain, a.k.a. Reno, a.k.a. Rhenus, a.k.a. Ryn) (from near Reichenau, Switzerland through Hoek van Holland, Rotterdam, Netherlands)
The Rhine river runs 6,560 furlongs in total length. The World War II Battle of Arnhem, as memorialized in the 1974 book and 1977 movie A Bridge Too Far, was the first of several attempts to capture key bridges across the Rhine, beginning with the Arnhem Bridge in the Netherlands.
It's about 350 times as tall as a Telephone Pole
In other words, the height of a Telephone Pole is 0.0027 times 20 furlongs.(a.k.a. Utility Pole, a.k.a Power Pole, a.k.a. Telegraph Pole, a.k.a. Telegraph Post, a.k.a. Hydro Pole) (exposed height; per Florida Public Service Commission average)
A standard telephone pole is 0.055 furlongs tall. Despite alternatives, most telephone poles in the US are made of wood — most commonly pine — and have a lifespan of 25 to 50 years, depending on climate and preservatives applied.
It's about 500 times as long as a London bus
In other words, the length of a London bus is 0.00208 times 20 furlongs.(Routemaster Double-Decker, RM standard specification)
The Routemaster Double-Decker buses, well-known as icons of London, measure 0.0417 furlongs in length. The buses were said to be well-designed for travel in the London traffic, as they offered an open door for riders to board and exit even while the bus was moving at low speeds, and a full-time conductor to collect fares.
It's about one-six-hundredth as long as The Colorado River
In other words, 20 furlongs is 0.00173 times the length of The Colorado River, and the length of The Colorado River is 578 times that amount.(a.k.a. Aha Kwahwat, a.k.a. Grand River, a.k.a. Tizon River, a.k.a. Tecon River, a.k.a. Tison River) (from Grand Lake, Colorado through the Gulf of California)
The Colorado River runs 11,600 furlongs in length. Along this length, the river descends from its source, approximately 13.70 furlongs above sea level in the Rocky Mountains, to its mouth in the Gulf of California.