News

Big changes for the National Bridge Inventory

Starting this year, the Federal Highway Administration is switching to a new system for measuring bridge conditions. It's very simple: bridges will be classified as Good, Fair, or Poor.

The term Functionally Obsolete has been retired, and Structurally Deficient is being redefined more narrowly so that it exactly matches the Poor condition on the new scale.

This seems like a good thing, as Good/Fair/Poor is much easier to explain. I'm looking forward to no longer fielding questions about the intricacies of the terms Structurally Deficient and Functionally Obsolete.

The Good/Fair/Poor scale is based on the ratings for Superstructure, Substructure, and Deck, as determined during each bridge inspection. If any of these three ratings are scored as 4 (Poor) or below, then the bridge is considered Poor. If all of the ratings are at least 7 (Good), then the bridge is considered Good. Otherwise the bridge is Fair. (Culverts have a separate rating field which works the same.)

States will be expected to decrease the number of Poor bridges and increase the number of Good bridges, and will be penalized by FHWA if they don't make adequate progress in that direction.

Interestingly, the new system does not take into account NBI ratings for "Structural Appraisal" and "Waterway Adequacy Appraisal." This means that it's possible for bridges previously considered Structurally Deficient to end up as Fair (instead of Poor) on the new scale. Indeed, doing some back-of-the-envelope calculations shows that this applies to 6,815 bridges. Of these, 756 are truss bridges.

Likewise, the elimination of the term Functionally Obsolete also makes a difference. Of those bridges previously declared as Functionally Obsolete, 53,937 now fit into the Fair category, and 21,750 qualify for the Good category. Among both of these groups, 1,972 are truss bridges.

The upshot -- and we can always dream -- is that a significant number of historic bridges, particularly truss bridges, won't be quite as juicy a target for replacement. It's been frustrating to watch perfectly sound bridges being demolished simply because they were too narrow and therefore "obsolete."

Of course, we have no idea how this will actually play out, but perhaps this will help some historic bridges avoid the wrecking ball. State DOTs will now be "on the clock" to prevent bridges from slipping from Good to Fair to Poor, and this will hopefully spur an emphasis on preventative maintenance and rehabilitation.

The latest NBI dataset from 2017 does not incorporate the new Good/Fair/Poor scale. However, it's easy enough to apply the new scale, so I've updated the data shown on Uglybridges.com and here on Bridgehunter.com to reflect the new system. I've retroactively applied the new scale to the archived data to make it easier to look at trends.

Comments  (11)

Big changes for the National Bridge Inventory
Posted February 18, 2018, by Margot

This definitely seems like a positive change that could save a lot of historic bridges as some of the ones previously branded as SD/FO are now Fair. Might this have the opposite effect on UCEBs? I'm thinking that they could slip down the scale more quickly since they usually need repaired or replaced more frequently. It would be nice if this helped to sway the general public opinion to favor historic bridges instead of relying on the cheap and ever-present UCEBs.

Big changes for the National Bridge Inventory
Posted February 17, 2018, by James Baughn (webmaster [at] bridgehunter [dot] com)

By popular demand, I've added more NBI data for the listings shown here.

I'm also renaming Uglybridges.com to BridgeReports.com to head off the complaints about whether a bridge is "ugly" or not. At some point, though, I might end up re-launching Uglybridges.com as a gallery of the most hideous UCEBs.

Big changes for the National Bridge Inventory
Posted February 15, 2018, by Steve Lindsey (stevelindsey60 [at] hotmail [dot] com)

Looks to me like a boon for bridge replacement. All the bullrush on infrastructure issues. A logical fallout from this trend.

Big changes for the National Bridge Inventory
Posted February 12, 2018, by Robert Elder (robertelder1 [at] gmail [dot] com)

Haha, Anonymous. I see what you did there.

I agree with Nathan that it would be great to see the FO/SD ratings from previous years.

Big changes for the National Bridge Inventory
Posted February 12, 2018, by Anonymous

So the term "functionally obsolete" is, in a sense, now functionally obsolete?

Big changes for the National Bridge Inventory
Posted February 12, 2018, by Nathan Holth (webmaster [at] historicbridges [dot] org)

I am confused, I understand the new system in replacement of SD/FO but do these ratings no longer exist?

Deck condition rating: Satisfactory (6 out of 9)

Superstructure condition rating: Fair (5 out of 9)

Substructure condition rating: Fair (5 out of 9)

Because these are very helpful to us and they are no longer showing on BridgeHunter!

Big changes for the National Bridge Inventory
Posted February 11, 2018, by Robert K. Thompson

I worked for a Director of Engineering who made it even simpler:

Is it "frowny face" or "smiley face"?

It certainly helped cut through the crap and the C.Y.A.

Big changes for the National Bridge Inventory
Posted February 11, 2018, by Robert Elder (robertelder1 [at] gmail [dot] com)

This wrought iron beauty is also rated as fair:

http://bridgehunter.com/ks/butler/80855306461/

This is encouraging. In many respects, I am happy to see the end of terms such as structurally deficient and functionally obsolete. These terms are often misunderstood by the General Public. A bridge that is functionally obsolete may still be very safe for travel and an outstanding condition aside from being too narrow by today's standards.

Likewise, structurally deficient does not necessarily mean that the bridge is going to collapse in the immediate future.

While the terms good, fair, and poor may seem over simplified, hopefully they won't be quite so frightening to the General Public as some of the current terms.

Big changes for the National Bridge Inventory
Posted February 11, 2018, by Robert Elder (robertelder1 [at] gmail [dot] com)

As a reference, this Marsh Arch, which has had relatively little repair work done in recent decades, is still rated as Fair:

http://bridgehunter.com/ks/montgomery/coffeyville/

This bridge could be repaired and maintained relatively easily and remain as fair or perhaps even get upgraded to good.

Now, could a state or county let a Fair bridge such as this one deteriorate to poor and then ask for federal funding? This unfortunate outcome has resulted in the demolition of a large number of historic bridges. It has also resulted in a terrible waste of taxpayers money.

If such abuse is discouraged, then perhaps states and counties will find that it can be financially advantageous to conduct preventative maintenance.

Big changes for the National Bridge Inventory
Posted February 11, 2018, by Robert Elder (robertelder1 [at] gmail [dot] com)

Pardon the typos. Voice to text sometimes fails me.

Big changes for the National Bridge Inventory
Posted February 11, 2018, by Robert Elder (robertelder1 [at] gmail [dot] com)

I can see a few different scenarios panning out here.

A good scenario would be the encouraging of rehabilitation of poor bridges and fair bridges. Bringing these bridges into good condition would help would be good to poor ratio.

Another scenario might be the abandonment of poor bridges. In other words, states and counties might simply pawn these poor nridges off onto unsuspecting landowners who would then be responsible for them.

A bad scenario would be the demolition, but not replacement, of poor bridges.

In short, there are several ways that this could pan out.