Author: Lorella Angelini, Angelini Consulting Services, LLC
I met Graham Bettis at the recent TSP2 SEBPP meeting in Charleston, WV, where he spoke about bridge preservation experiences at the Texas Department of Transportation (TxDOT) in the events of extreme flooding.
Graham has developed a vast and diverse bridge preservation experience at TxDOT. With 53,875 bridges in its 2016 inventory, this state has the largest number of bridges in the USA. The Texas bridge inventory consists of 35,489 “on-system” bridges, which are located on the state highway system and maintained by TxDOT; and 18,386 “off-system” bridges, which are not part of the state highway system and are under the jurisdiction of the local governments (cities, counties, and municipalities).
Graham is the Director of Field Operations for the Bridge Division at TxDOT. His responsibilities include the bridge inspection program and the management of the geotechnical group, in addition to bridge construction and maintenance. Graham is a member of the TSP2 SEBPP Committee.
What does bridge preservation entail at TxDOT?
Since 2001 a primary focus at TxDOT has been addressing Structurally Deficient (SD) bridges, an effort that was fully supported by our Administration. We have been very successful with this. The number of on-system SD bridges in Texas decreased from 483 in 2006 to 187 in 2016, while the number of off-system SD bridges in Texas decreased from 1,642 in 2006 to 678 in 2016. Now that the number of SD bridges is low, we have a unique opportunity to focus on developing and implementing an overall bridge asset management program.
It is worth noting that an SD bridge is one with maintenance concerns or one that frequently floods. SD bridges do not pose a safety risk; however, to remain open to vehicular traffic, they are often posted with reduced weight limits that restrict the gross weight of vehicles using the bridges. SD bridges are inspected frequently and are closed to the traveling public if determined to be unsafe.
Could you talk about the bridge asset management program at TxDOT?
In the last two years we established the Bridge Maintenance and Improvement Program (BMIP), which is entirely focused on bridges that are in “fair” condition.
The number of bridges in “good” condition in Texas is increasing, while the number of bridges in “poor” conditions is decreasing, which is what we want. However, the number of “fair” bridges is increasing because we have a number of “good” bridges that are becoming “fair.” So we really want to concentrate on hitting those “fair” bridges that have a condition rating of 5 or 6 and push them back up to “good” so as to maintain their service life in an economically efficient manner.
How has the BMIP evolved over the past years?
The program is still in its infancy. It began three years ago and we have just one engineer to oversee it. In the first couple of years we were focusing on 10-12 bridges per year, mainly large projects. Now we are addressing 70-80 bridges per year, which is in line with BMIP target.
Could you highlight the key elements of the bridge preservation strategy at TxDOT?
As I said before, a key element is to identify those structures where it makes financial sense to address defects early on and get ratings back up to good (condition ratings of 7 or higher – ed. note).
We are also working on a bridge life-cycle cost analysis, in which we compare the cost of repair/rehab versus replacement. While some rehab measures are very cost effective, others are extremely expensive. We want to have a method that allows us to identify those bridges that can give us another 5 or 10 years of service life before replacing them versus investing in rehabilitation.
If it costs $1M to rehabilitate a bridge today, compared to $1.5 M to replace it 10 years from today, we will likely choose the replacement because the level of quality we get out of new bridge construction is very high. Even if it costs more initially, replacement is an economical solution in the long run because we will get 100 years of service life out of a new bridge.
The goal of the rehabilitation program at TxDOT is to extend the service life of bridges by 25 years, which is one-fourth of the service life extension we get with replacement. In other words, even successful repairs have fairly limited effective life in comparison with new construction.
We are trying to improve all aspects of rehabilitation, from engineering evaluation to plan preparation and actual quality of the work itself. None of these aspects are quite as effective as for new construction. There are a lot of opportunities for improvement in repair and rehabilitation.
What are the challenges in the implementation of the bridge preservation strategy at TxDOT?
The sheer magnitude of the number of bridges in Texas represents the main challenge in the implementation of our long-term goal to reverse the trend of bridges in “fair “condition. We have to deal with financial constraints and limited resources that do not match such a massive inventory.
A major implementation challenge also entails convincing our own Districts to dedicate some of their resources to cyclical bridge maintenance. We can strive to build bridges that are as maintenance free as possible, but at some point cyclical maintenance is necessary in order to extend the life of a structure. Cyclical maintenance does not cost much and it is really effective keeping small problems from becoming big ones. We know, for example, that if we do not take care of relief joints in approach slabs, the abutments will start pushing on the bridge ends, which is a major problem. Joint repair, clearing drains, cleaning caps’ tops are examples of cyclical maintenance at TxDOT.
With so much focus and resources on maintaining pavements, it is challenging to bring the attention of the Districts to bridges and convince them to think about bridges in the same way as they do about pavements.
Pavement problems are always front and center for Districts, while bridge problems are usually less visible. Since pavements and bridges are part of the overall asset, there should not be a dividing line between them.
Management of pavements and bridges runs on two parallel yet separate tracks to the point that there are different pavement and bridge maintenance crews. I think that pavement and bridge practitioners should work together on preservation issues.
Is TxDOT involved with off-system bridges?
Yes, we inspect them and we financially support their replacement. If there is a critical finding or a closure is going to happen, we then get involved with the owner–the county, municipality, or city—to determine what needs to be done.
Overall we have far less control of the off-system bridges in comparison with the on-system bridges. We also are not involved with the maintenance of off-system bridges. It is up to the local owners to maintain these bridges. There is little, if no, maintenance for off-system because of limited resources for a large number of bridges.
Is TSP2 helping reach your goals?
What I like of TSP2 is that it is getting us all together and giving us an opportunity to talk about things that are working and not working with bridge preservation.
While so much of the focus nationally is on data collection to the point that we are dealing with data overload to some degree, TSP2 is refreshingly down-to-earth since it focuses on the nitty-gritty details of bridge preservation.
In a conference like this (SEBPP ed. note) we sit with consultants, suppliers and contractors exchanging information. There is always something that we can bring home and make use of.
What can TSP2 do to improve its program?
Maybe TSP2 can find ways to keep bridge preservation practitioners connected during the year through webinars and conference calls so as to build on the annual conference. Sharing information through websites and social media is effective, but there is nothing like putting a date in a calendar and attending a meeting, even if it is simply by web connection.
Our TSP2 SEBPP committee core group has already implemented a strong communication process with calls once or twice a month. We should consider improving communication beyond our core group by increasing the amount of time that bridge practitioners from different states talk with each other and exchange information.
Report on Texas bridges: