Other Construction Projects Chapter 18

Highways (Pg 383) Flexible Roadway Sub grade (Packed Soil) Sub base (Sand or gravel) Pavement (Asphalt Layer. Rigid Roadway Sub grade (Packed Soil) Sub base (Sand or Gravel) Steel Bars Pavement (Concrete)

Substructure of Bridges Abutments -are the supports at the end of the bridge. Piers – Vertical structural supports placed between abutments in longer bridges Span – The distance between each pier is called a span. Piles – A solid base that the piers rest on.

Piles

7 Types of Bridges Beam Bridge Arch Bridge Truss Bridge Cantilever Bridge Suspension Bridge Cable-Stayed Bridge Movable Bridge.

Beam Bridge Piers support beams that support spans of reinforced concrete slabs. This is the most frequently used type of bridge because it is normally least expensive.

Arch Bridge The load of the bridge is transferred along the arch to the abutments or piers at the end of the arch.

Truss Bridge Trusses may be used above or below the roadway to support the bridge.

Cantilever Bridge Beams called cantilevers extend from each end of the bridge. They are connected by a section called a suspended span.

Suspension Bridge These have two tall towers that support main cables that run the entire length of the bridge.

Cable-Stayed Bridge These are similar to suspension bridges except the cables are connected directly to the roadway.

Movable Bridge These bridges are designed so that a portion of the roadway can be moved to allow large water vessels to pass underneath.

Dams A dam is a structure that is placed across a river to control or block the flow of water. A reservoir is a lake in which water is stored for use. Dams may be made of earth, concrete, steel, masonry, or wood.

Dams Embankment – blocks the flow of water. Outlet Works – used to control the flow of water through or around the dam. Spillway – acts as a safety valve that allows excess water to bypass the dam when it becomes too full. Cofferdams – Temporary watertight walls.

Canals Irrigation Canals – Carries water from a place where water is plentiful to another place where water is needed. Navigation Canals – Connects two bodies of water. Construction of a canal requires earth moving. Navigation canals may also require the construction of locks if the two waterways being connected are at different elevations. A lock is an enclosed part of the canal that is equipped with a gate.

Canal Lock

Three Types of Tunnels Earth – are constructed in soil or sand. These are hazardous to build because soil can be unstable. Immersed – pre-manufactured sections are floated to the tunnel site. The sections are connected. Rock – blasting away material or by using a giant boring machine. Conveyors carry out rock and the tunnels are formed.

Pipelines Are an efficient way to transport products such as crude oil, refined petroleum, and natural gas. Most pipelines are buried underground.

Air-Supported Structure There is no frame or load-bearing wall to support the roof. Air pressure supplied by a fan supports the walls and the roof.

Review Surveying, earthmoving, and paving are used to build roads and highways. Types of bridges included beam, arch, truss, cantilever, suspension, cable stayed, and movable Dams provide a dependable water supply, help control flooding, and provide hydroelectricity.

Review Canals are built for navigation or irrigation and may require locks. The three main types of tunnels are earth, immersed, and rock. Most pipelines are buried underground, with only the pumping stations above ground. Air-supported structures consist of a structural membrane supported by air pressure.