About the Author:  Sean Gorman founded FortiusOne in 2005 to bring location based analytics to the mass market. Sean brings over 10 years of experience at the forefront of the geospatial revolution as a researcher, practitioner, and entrepreneur at FortiusOne. Through both academic and entreprenurial efforts he has been working to make geographic data more accessible to the public since 1997 culminating in the creation of GeoCommons – a crowd-sourced repository of statistical data and social feeds that can be easily mapped, remixed and reused by non-technical users. Sean has been featured in media such as, Wired, Der Spiegel, ABC, Washington Post, Business 2.0, MSNBC, CBS and CNN. He also holds a PhD. From George Mason University in Public Policy where he was the Provost’s High Potential Scholar and was the recipient of the Fischer Prize. He has published dozens of articles on geographic data sharing and analysis, and authored the book Networks, Complexity and Security: The Role of Public Policy in Critical Infrastructure Protection. Read more from this author

Yesterday’s story of the I-35W bridge collapse in Minneapolis was both tragic and scary. The event has quickly raised the question of how safe are America’s bridges. There is a very comprehensive set of data on America’s bridges called the National Bridge Inventory (NBI) maintained by the Federal Highway Adminsitration. The NBI has tons of data that is very useful for public safety purposes. Lets take the Interstate 35 West bridge that collapsed in Minneapolis yesterday.

According to the NBI the bridge (structure number 9340) has the following characteristics

-Owned and maintained by: State Highway Agency
-Structure Length: 581.3 m
-Bridge Roadway Width: 31.7 m
-Operating Rating: 53.9 Metric Tons
-Navigation Vertical Clearance: 19.5 m
-Minimum Vertical Underclearance: 4.82 m over Highway
-Number of Spans in Main Unit: 3 Spans
-Material Design: Steel continuous
-Design Construction: Truss – Deck

More importantly the NBI also includes the latest safety evaluation of the bridge:

-Deck Condition: Fair Condition
-Superstructure Condition: Poor Condition
-Substructure Condition: Satisfactory Condition
-Scour: Foundations determined to be stable for assessed scour conditions
-Bridge Railing: Meets currently acceptable standards.
-Structural Evaluation: Meets minimum tolerable limits to be left in place as is
-Water Adequacy Evaluation: Superior to present desirable criteria
-Estimated Total Improvement Project Cost: $3019000
-Year of Project Cost Estimate: 2003
-Average Daily Traffic: 141000
-Year of Average Daily Traffic: 2004
-Sufficiency Rating: 50 %

So we now know quite a bit about the bridge that collapsed 1) it had superstructure rated poor 2) met the minimum tolerable limits to be left in place as is 3) since 2003 the Minneapolis DOT had known it would only take $3 million to fix it 4) 141,000+ people per day were at risk from the substandard bridge.

This data should have been made easily available to the citizens of Minneapolis, but instead it is hidden deep in bowels of exceeding difficult to use data files (ASCII…bleh). Having worked with the NBI before it still took me most of the morning to dig the data out and try to make some useful maps. Hobbyists do a better job of making the data usable. I have to believe that if citizens knew this information pressure would have been placed on the politicians to do something about the bridge to expedite the repair work.

In order to take a look at the larger issue we mapped out the aggregate data for all the structurally deficient and functionally obsolete bridges by State.

The scary bit is that Minnesota is one of the better states in aggregate…

It is also to useful to see this data normalized to see how many deficient bridges there are per 100 bridges

Again Minnesota is on the low end with 8.7 deficient bridges per 100 bridges. The top state Oklahoma 26.8 per 100 followed by Rhode Island at 25.3 and Pennsylvania at 25.0.

Before 9/11 all the bridges came with latitude and longitude coordinates that would have allowed the data to be mapped so anyone could see if there was a structurally deficient bridge on their daily commute. That is one of the trade offs of tighter security a loss of public safety information. Unfortunately it is only after tragic events like 9/11 or a bridge collapse that the issue gets addressed. Whether you fall on the side of more security or more safety awareness there needs to be better mechanisms by which to make the data easily consumed – be it a select few government officials or the public.

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