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An Introduction to Historic Bridges

Informative Guides and Tutorials

These presentations are your door to the vast, rich world of historic bridges. If you are new to the world of historic bridges and are confused by any of the terms used on HistoricBridges.org and other bridge websites, these presentations are for you. If you are looking for a list of truss bridge configurations with example bridges, these presentations are for you. Finally, if you want to document historic bridges like HistoricBridges.org, or learn more about HistoricBridges.org, than this is the right place to be. Presentations are offered in Adobe PDF and Microsoft PowerPoint 2007/2010 versions. If you do not have Microsoft PowerPoint 2007 or later you can download Microsoft's free PowerPoint Viewer, a 61mb download by clicking here.

Historic Bridges: The Crash Course


Possible Titles:

Doing More With Less

Safer, Better Bridges



A primary funding focus on maintenance, repair, and rehabilitation in that order with a reduced focus on replacement except where safety or function are genuinely compromised will reduce costs (or allow money to be spread out further), and improve the nation's bridges.


Current Bridge Problems

Deteriorating Bridges

Limited Funding

National Debt and Budget Deficit


Current Issues. Problems With Current Bridge Policy


The Solution


Little Side Box

Did You Know?

The I-35W Bridge in Minneapolis collapsed in 2007, killing a number of people. It did not collapse because it was deteriorated. The bridge was improperly designed from the day it was built, because the gusset plates that held the truss members together were not as thick as they should have been. A combination of rush hour traffic and weight loads associated with repair activities were too much for the faulty gusset plates to support. Following the collapse, all bridges similar in appearance and design to this bridge have been carefully reviewed by engineers and inspectors to make sure that no other bridges had similar problems. Other bridges that may look like the I-35W Bridge can often be



Concepts of Questionable Validity To Overcome

Service Life - The concept that a bridge has a set lifespan that when achieved requires complete bridge replacement.








New Concepts To Consider

Replacement By Rehabilitation - Nothing lasts forever, yet total bridge replacement may not always be needed to address this reality. When a bridge is rehabilitated, those parts that are severely deteriorated are often replaced. Over a long period of time, if rehabilitations were conducted time and time again, different parts of the bridge requiring replacement each time, eventually nothing of the original bridge would remain. In this way, rehabilitation can provide the value of fixing existing infrastructure, while providing the longevity and function of new infrastructure, and can eliminate the need for a total replacement project to ever occur.

High Quality Rehabilitation - Often, when engineers design a rehabilitation they design one that is expected to last 25 years. Some engineers however choose to conduct a more comprehensive and meticulous rehabilitation that may provide up to 75 years of continued service life. These longer-lasting rehabilitation projects will provide much better value.

Turn Functional Obsolescence Into Traffic Calming - The 2011 Toward Zero Deaths campaign aims to reduce highway fatalities. What about the argument that a bridge is too narrow to be safe, for example? Rather than assuming that replacement is the only way to make this bridge safe, consider adjustments to the roadway it serves to turn a traffic hazard into a traffic calming measure. Traffic calming is a way in which safety can be increased on a roadway.

New Bridges Instead of Replaced Bridges




Other Viewpoints

AASHTO: Bridging the Gap: Restoring and Rebuilding the Nation’s Bridges - (PDF Version)

National Surface Transportation Policy and Revenue Study Commission - Transportation For Tomorrow - (PDF Version)

Better Roads - The State Of Your Bridges - This article is interesting because a significant number of highway agencies comment that they wish they had more funds for maintenance.

FHWA - 2008 Status of the Nation's Highways, Bridges, and Transit: Conditions and Performance - (PDF Version)

Transportation Association of Canada - The AASHTO of Canada

Bridge Aesthetics (PDF Version)

Transportation For America (PDF Version)





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