Structures Need Rehab - Part 1

Oct 14, 2015


Corbett Freeman, P.E.

Money for infrastructure always seems to be scarce, but our great “Bayou City” continues to grow and, at the same time, continues to age. Without needs-based programs like ReBuild Houston that prioritize replacement of crumbling infrastructure, a full eighty percent of drainage structures and streets will outlive their useful life in the next 20 years. Nationally, the last increase in the gas tax, which generally pays for our transportation system, was over 20 years ago. That bill, however, was passed to balance the budget, not to pay for new and replacement infrastructure.


In the structural department, we are acutely aware of condition issues with infrastructure. A pothole, broken curb, or a plugged drain can be much more than a nuisance. But unsightly rust, cracks, and exposed rebar on bridges, culverts, and other critical structures tend to cause public concern. This is the stuff that makes local headlines, whether the stories behind the headlines are completely true or not.


As our facilities age and suburban development continues, structures must be rehabilitated, expanded, or replaced. Even after a string of successful votes in support of transportation and water infrastructure, funds will remain outmatched by our current needs. As voters, we must continue to stay engaged in decision-making to ensure that funding is available to maintain our standard of life. As engineers, however, we are left asking ourselves in many cases, “How can we squeeze more life out of the structures that we already have?” Foremost on our minds is a cost-effective rehabilitation without sacrificing public safety.


District engineers have seen this type of rehabilitation and reconstruction play out many times over the years in water, wastewater, and other facilities. They are often called upon to replace or add hydro-pneumatic tanks, retrofit existing pump stations, rehabilitate lift stations, and add generators. These projects are much smaller in scope than any new plant, but always have a structural component for us to complete.


It is definitely worthwhile to spend more on engineering in order to get a cost effective solution instead of a cookie-cutter package that may waste precious funding. Around 10 years ago, I was assigned to a highway project with the Ohio Dept. of Transportation that really opened my eyes to this type of thinking. Instead of just preparing a set of construction plans, the structural team went to great lengths to analyze each component of the existing bridges to determine what portions could remain and the items that definitely had to be replaced. On the bridge that I worked on, we decided to replace the entire concrete deck and the outside girders, then widen the structure. Here in Texas, the typical procedure is to make an early decision either to widen the existing bridges or replace all the bridges with wider structures. Rehabilitation is limited to sealing up joints and patching some concrete.


Rehabilitation of an existing structure may not be the high profile structural work that we all desire to be involved in, but these types of projects can fill a necessary void and greatly stretch our infrastructure funding.


Next up – What is a structurally deficient or functionally obsolete bridge?

 


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