National Bridge Inventory software

The National Bridge Inventory is a nationwide database of bridges that carry traffic on public roads, based on inspection data submitted by each state. Despite its many flaws, oddities, and omissions, the NBI has formed the backbone for's database.

After years of arguing that disclosure of the NBI would be a "national security risk", the Federal Highway Administration posted the database online a few years ago. However, like many public data sources, it's in a very inconvenient format, in this case featuring fixed-width ASCII text columns that represent bleeding-edge technology... for 1983.

I've spent a fair amount of "quality" time working with the NBI data. As a result, I'm happy to announce OVERPASS, a new program for converting the raw ASCII text format files into something more useful. (No surprise, OVERPASS is a acronym: Online Versatile Engine Reporting, Presenting, And Studying Spans).

You can download it here. It requires the Perl programming language and access to a command line, so this isn't for newbies. However, it's straightforward to convert each state into a CSV file suitable for importing into Excel, OpenOffice Calc, Access, or the spreadsheet/database program of your choice.

To use the program, first run overpass --help to see a help screen that shows all of the options. Then you'll do something like overpass mo09.txt > mo09.csv to make the conversion.

Hopefully the FHWA will eventually make the NBI available in a more user-friendly format. Until then, if you're a serious bridgehunter, the OVERPASS program is available to turn the NBI into something half-way useful.

Comments  (5)

National Bridge Inventory software
Posted October 7, 2013, by ben feldman (knicnak32 [at] gmail [dot] com)

i also wrote a javascript version at

feel free to post comments/bugs there! i'm looking for feedback and contributors!

National Bridge Inventory software
Posted September 20, 2013, by Damian (dspangrud [at] esri [dot] com)

Great software - but I found a problem. It appears some of the records now have Lat / Long that have decimals in the DMS input and when it comes out on the parsed item you lose the decimals.

For example - in Colorado the Structure num: DEL3400D-1.0-50

(data from CO12.txt file from NBI site)

It's XY - input have

Latitude: 38 42 00. N

Longitude: 1 07 42.00 W

But when put through overpass I get

Latitude: 00-38-42

Longitude: 001-07-42

I'm not sure if this is an issue with the source data or the compass program.

Any ideas?



National Bridge Inventory software
Posted July 28, 2010, by Nathan Holth (form3 [at] historicbridges [dot] org) is partially broken and no longer being updated so its not the most current NBI. Some states still work, but other states fail to load the detail sheets for a bridge when you click on them. It also does not provide the full NBI data set.

National Bridge Inventory software
Posted July 24, 2010, by D. Thomsen (dcthomsen [at] comcast [dot] net)

There is, of course, the National Bridge Inventory search, by Alexander Svirsky, at as an alternative. Sad that the federal government spends billions, but does not let the average citizen use the NBI with an easy to use search engine.

National Bridge Inventory software
Posted July 23, 2010, by Nathan Holth (form3 [at] historicbridges [dot] org)

This is a fantastic program! For the benefit of others, I wanted to offer a few tips.

-This program allows you to convert additional useful technical data contained in the NBI that is not shown on BridgeHunter listings by default, such as sidewalk widths, truck traffic counts, clearances, etc.

- I was able to create conversion of the data to Microsoft Excel and then design a Microsoft Access Form that displays the data in a convenient format. Here is an example: which shows you the breadth of data contained in the full NBI.

-If you want to run this program on your Windows computer, I suggest downloading the free ActivePerl program here: It works great. Install the program, then copy the OVERPASS files and the NBI ASCII files into the C:\Perl\bin folder. Then just use the old DOS Command prompt (in Windows XP, this is in the Accessories menu). From the dos prompt, type

cd C:\Perl\bin

to navigate to the directory. Then to run OVERPASS with the syntax help, type in

perl overpass --?

Remember in the DOS Command Prompt, you always have to begin your syntax with

perl overpass