A multi-way bridge is a

bridge A bridge is a structure built to Span (engineering), span a physical obstacle (such as a body of water, valley, road, or railway) without blocking the path underneath. It is constructed for the purpose of providing passage over the obstacle, whi ...

with three or more distinct and separate spans, where one end of each span meets at a common point near the centre of the bridge. Unlike other bridges which have two entry-exit points, multi-way bridges have three or more entry-exit points. For this reason, multi-way bridges are not to be confused with commonly found road bridges which carry vehicles in one direction from one entry point, and then bifurcate into two other one-way bridges.

Description

Multi-way bridges are located throughout the world, though they are rare. Some are as small as a

footbridge A footbridge (also a pedestrian bridge, pedestrian overpass, or pedestrian overcrossing) is a bridge designed solely for pedestrians.''Oxford English Dictionary'' While the primary meaning for a bridge is a structure which links "two points at a ...

, while others are multi-lane roadways. Three-way bridges are often referred to as "T-bridges" or "Y-bridges", due to their shape when viewed from above. Three cities in

Michigan Michigan ( ) is a peninsular U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest, Upper Midwestern United States. It shares water and land boundaries with Minnesota to the northwest, Wisconsin to the west, ...

each have a three-way bridge named "Tridge", combining "tri" and "bridge": The Tridge (Midland, Michigan), The Tridge (Ypsilanti, Michigan) and The Tridge in

Brighton, Michigan Brighton is a city in Livingston County in the U.S. state of Michigan. As of the 2020 census, its population was 7,446. Brighton forms part of the South Lyon-Howell-Brighton Urban Area. It is one of two incorporated cities in Livingston County ...

. The unique shape of a multi-way bridge makes it easy to identify from an airplane. Pilot

Amelia Earhart Amelia Mary Earhart ( ; July 24, 1897 – January 5, 1939) was an American aviation pioneer. On July 2, 1937, she disappeared over the Pacific Ocean while attempting to become the first female pilot to circumnavigate the world. During her li ...

described

Zanesville, Ohio Zanesville is a city in Muskingum County, Ohio, United States, and its county seat. Located at the confluence of the Licking River (Ohio), Licking and Muskingum River, Muskingum rivers, the city is approximately east of Columbus, Ohio, Columb ...

as "the most recognizable city in the country" because of its Y-shaped bridge, and the pilots of ''

Enola Gay The ''Enola Gay'' () is a Boeing B-29 Superfortress bomber, named after Enola Gay Tibbets, the mother of the pilot, Colonel (United States), Colonel Paul Tibbets. On 6 August 1945, during the final stages of World War II, it became the Atomi ...

'' aimed for Hiroshima's T-shaped

Aioi Bridge The is an unusual T-shaped three-way bridge in Hiroshima, Japan. The original bridge, constructed in 1932, was the aiming point for the 1945 Hiroshima atom bomb both because its shape was easily recognized from the air and its location was ...

when they dropped the atom bomb. While designing the Tripartite Bridge in 1846—a Y-bridge proposed to span the

Allegheny River The Allegheny River ( ; ; ) is a tributary of the Ohio River that is located in western Pennsylvania and New York (state), New York in the United States. It runs from its headwaters just below the middle of Pennsylvania's northern border, nor ...

and

Monongahela River The Monongahela River ( , ), sometimes referred to locally as the Mon (), is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed August 15, 2011 river on the Allegheny Plateau in nor ...

Pittsburgh Pittsburgh ( ) is a city in Allegheny County, Pennsylvania, United States, and its county seat. It is the List of municipalities in Pennsylvania#Municipalities, second-most populous city in Pennsylvania (after Philadelphia) and the List of Un ...

, Pennsylvania—engineer John A. Roebling identified one of the challenges of erecting a three-way suspension-type bridge. Suspension-bridge cables on two-way bridges support heavy loads and are anchored solidly at either end, while on a three-way bridge the cables of each of the three spans need to anchor at a central pier in the water, where cable forces from each span would have to balance each another: "the intersection of the cables at the top of the center pier...would have created enormous horizontal forces, and the stone arches connecting the three towers could hardly have resisted the tensions imposed by the cables radiating from their tops." The bridge was never built.

Description

Three-way bridges

Four-way bridges

Five-way bridge

References