‘Bridge’ Tag

Failing Infrastructure

Photo Credit: Karl Jansen

This is the infamous Stadium Blvd Bridge in Ann Arbor, MI. For the past several years, this bridge has literally been falling down, waiting on funds for a rehabilitation project. What you see on the near side of the bridge is an exposed beam, which used to be the south side of the bridge. Last year, the south half of the bridge was removed for public safety reason, because officials were worried “football size” chunks of concrete would fall on a car or pedestrian. This fall, the City of Ann Arbor with its secured funding will finally undertake this long overdue project.

Cloverleaf Interchange

Photo Credit: Brian Wolfe

This is a great example of a classic cloverleaf interchange of a major road and a highway. The cloverleaf interchange gets its name from its shape. Half of the ramps, where the driver would normally make a right turn at an at-grade intersection, are smooth curves on the outer edges of this interchange. The other half of the ramps, where the driver would normally make a left turn to get on the other road, are 270-deg loops on the inner part of the interchange. They have been a popular choice by transportation engineers for many decades, but recently they are being replaced by safer and more efficient interchanges. The problem with the cloverleaf interchange has to do with the merging in/out of the loop ramps, especially when there is a heavy slow-to-accelerate truck in the mix which are also prone to roll-over accidents.

Swing Bridge

Photo Credit: Alex Mead

Seen above is a swing bridge over a small river near Detroit, MI. The concept of a swing bridge is similar to a draw bridge in that the bridge is movable to allow traffic to pass through the area it spans. This allows a smaller bridge to be built than would otherwise be necessary for height clearance purposes. The swing bridge operates by rotating around the central pivot of the span to clear the area above the water surface to allow vessels to pass. The bridge is currently in the “closed” position and would be perpendicular to the screen if it were rotated to the “open” position to allow traffic to pass.

Large Bridge Pier with Bumpers

Photo Credit: Alex Mead

Seen here are two piers of the I-75 bridge over the Rouge River in Detroit, Michigan. The four columns support the entire weight of the bridge above and carry the load to the foundation under the surface of the water. As a result the piers need to be protected from potential impacts with vessels traveling on the water. To protect the piers engineers design barriers made of numerous logs driven into the bottom of the river bed. These barriers are then bound together with loops of steel cable. By binding the logs together the strength of the barriers greatly increases.

Roller Support

Photo Credit: Karl Jansen

This is a roller support. It is one of the most common types of structural supports used by civil engineers. This roller support allows for the supported structure to move horizontally, while the upward reaction force prevents the structure from falling down. The single reaction force is always perpendicular to the surface and in the direction away from that surface (normal). This type of support is often found at one end of a long bridge, allowing the bridge to expand and shrink with the natural temperature changes.

Suspension Bridge Cable Embankment

Photo Credit: Alex Mead

Seen here is the cable anchorage for the Ambassador Suspension Bridge over the Detroit River. This large mass of concrete is designed to deliver the opposing forced on the main cables of the bridge after they have passed over the towers. In the concrete mass the seemingly large single cable actually breaks apart into the smaller cables it is made of for anchoring purposes. The length of each cable embedded in the concrete is very important to prevent pull out of the cables and is calculated according to reinforced concrete code ACI 318.

Pedestrian Bridge over Highway

Photo Credit: Alex Mead

Seen here is a pedestrian bridge over I-75 in Detroit, Michigan. This type of bridge is important because it allows pedestrians to cross to the other side of the freeway without crossing on the road level or having to go to the nearest street crossing bridge. When new highways are being planned and approved features such as pedestrian bridges and sound barriers are many times included. These features are aimed at local people near the project to allow them to live and work near such highways as comfortably as possible.

Stalled Bridge Project

Photo Credit: Alex Mead

Seen here is the end of the Ambassador Bridge that extends from Detroit, MI, USA to Windsor, Ontario, Canada over the Detroit River. This particular picture is of the ramp up to a proposed second crossing. However, the permits were not issued and the project was therefore halted and now stands with a drop off to nowhere. The lesson from this is quite straight forward: get your permits before you start the project or you may end up with a useless piece of infrastructure.

Arch Bridge for Utilities

Photo Credit: Alex Mead

As seen here bridges don’t always carry people in cars or trains over obstacles. This is a bridge in Detroit, Michigan at the Ford Motor Company Rouge River Plant. This factory is so large that roads actually pass through the complex requiring utilities, such as steam pipes, to cross the road to access different parts of the plant.