Percent of major bridges in good to excellent condition

Status

Most major bridges in Austin are critical creek crossings, which provide safe, functional access within our transportation system. Bridges are subject to heavy traffic loads, constant erosion, and debris impacts during flooding events. Routine, thorough inspection is necessary to assure public safety and continuity of the transportation network.
Poor structures on the bridge network run the risk of more excessive damage that normally could have been addressed with maintenance and repairs before it became critical. Furthermore, poor structures may have to be load posted which severely limits their use to heavier truck traffic. Ultimately, bridges in poor condition could fail requiring extensive repairs or even replacement.
"Major bridges" are those that are at least 20 feet long and inspected by the Texas Department of Transportation every two year.  Our major bridge network consists of 452 bridges, and 407 bridges are in good to excellent condition. However, the average age of our bridges is 44 years. There are 129 bridges that are older than their design life of 50 years. While still safe and useful, this large number of bridges are well beyond their expected life. It is necessary to plan for a steady repair, rehabilitation, and replacement program over time as these structures continue to age and naturally deteriorate.
Continuously assessing and meeting this performance target provides reassurance that there are no significant concerns with safety and unrestricted use all of Austin’s bridges.

Trending

As we can see, the percentage of major bridges in good or better condition obviously increases in 2017, but a slow decline overall in 2019 is observed. However, despite the logistical issues caused by the COVID-19 pandemic, the bridge performance meets its 90% target in both 2020 and 2021.
Along with the structural impacts caused by major floods, growth in heavy traffic such as transit buses and large trucks can negatively affect Austin’s bridge performance over time.
The average age of our bridges will eventually start requiring replacements given expected normal aging and deterioration, as well as older bridges not meeting modern standards and criteria due to age.  For instance, many older bridges feature narrow sidewalks, lack of bike lanes, too few traffic lanes, no shoulders, and bridge railing inadequacy.
NOTE: To see the underlying data or this chart, please select the "View Source Data" link above. 

Additional Measure Insights

There are topographic differences throughout Austin which correspond to the creeks and watersheds. Bridges have been constructed where roadways need to cross these waterways. Older bridges are typically found in older parts of Austin. These older bridges do not always have worse conditions but do usually feature more obsolete structures.
Some of older bridges do not allow for an adequate waterway opening and so are substandard from a drainage perspective. Some can be modified, but eventual replacement is the best option for most of these structures. Eventually, we will need to begin replacing bridges at a significantly faster rate than we’ve experienced up to this point, which can be for obsolescence, structural, or drainage needs.

Measure Details and Definition

1) Definition:  This measure tracks the percent of major bridges in Austin which are in good to excellent condition.

2) Calculation method: The number of major bridges with sufficiency ratings greater than 70 divided by the total number of major bridges.

3) Data Collection Process:  Bridges and culverts are inspected visually on a cycle. The major structures having openings 20 feet or greater are inspected every other year by TxDOT. These inspectors are certified by TxDOT for their Bridge Inspection and Appraisal Program (BRINSAP) which in turn reports to the Federal government’s Nation Bridge Inventory System (NBIS). TxDOT shares the biennial inspection reports with the City for our local “off-system” non-highway bridges. Inspection of the smaller minor structures is not mandated by the Federal government and so is managed entirely by the City.

4) Measure Target Calculation: Failed structures would obviously be intolerable as they would have to be closed. Furthermore, the goal of having no poor structures is based on having no seriously deficient structures. This is the safest possible policy to assure the welfare of the public and continuity on our transportation system.

5) Frequency Measure is Reported: Annual (Fiscal Year)

Date page was last updated: April 2022