America’s roads are in disrepair. Our road system has a D rating, with the rest of our infrastructure in the same grade range (C-), according to the American Society of Civil Engineers (ASCE).
Now that the bipartisan Infrastructure Investment and Jobs Act (IIJA) has become law, communities are finally able to upgrade and modernize their existing infrastructure. But what is the best way to upgrade our roads when the choices are between rehabilitation and reconstruction?
Reconstruction is defined as “to comprehensively rebuild to a new condition with current criteria,” according to Maintaining Houston’s Streets, an informational document released by Houston officials. Reconstruction is used to rebuild subgrade, roadway base, new roadway surfaces, signage, marking, and much more.
Rehabilitation, on the other hand, restores to near original condition, which is used for distressed streets where the overall ride has degraded.
“Roadway rehabilitation is performed instead of reconstruction to save cost and better manage the limited funds that state DOTs and other owners receive,” said David Hamlet, vice president and highway section manager at Gannett Fleming, Inc. “A rehabilitation project can extend the life of a facility for many years at a fraction of the reconstruction cost. Owners use preventive maintenance to keep infrastructure in good condition for as long as possible.”
Rehabilitation seems like the obvious solution, especially as states receive the funds from the IIJA to invest in and modernize our roadways.
Looking at the cost of road rehabilitation compared to reconstruction, despite variables on what type of road, the length of road, etc., rehabilitation seems like the cheaper solution to this question. Of course, we must keep in mind that not every road project can be a rehabilitation. Depending on the damage and deterioration to the roadway, sometimes reconstruction is necessary.
However, when looking at road rehabilitation projects, what goes into them? And how can contractors, departments of transportation, and communities get the biggest bang for their buck?
Technology for Rehabilitation
Thanks to technological advancement, it is much easier for state DOTs and construction companies to find the cause of the problem with the infrastructure they are trying to upgrade.
“Technology has given DOTs the ability to non-destructively test pavement conditions and identify areas that are performing poorly and in need of rehabilitation even when visual inspection may give you a different answer,” said Jon G. Whitney, vice president and senior project manager at HNTB. “These non-destructive tests can give information on subgrade and pavement conditions identify poor performing pavements or areas that may only need resurfacing, allowing DOTs to spend their rehab budgets wisely.”
Now, construction companies and DOTs have a variety of new and improved technology for use in their road rehabilitation projects. Computer modeling, eco-friendly ingredients, and water-saving pavements all factor in to the cost, as well as the overall execution of completing these projects.
Big improvements to scanning technology can determine the condition of the pavement and the materials below the pavement. It is now possible to scan pavement while moving at full highway speeds and determine the condition of the pavement surface.
Pavement mix designs have improved over the years. The development of stone matrix mixes has provided the industry with more stable overlays, which in turn extend the life of rehabilitation projects. New software has improved pavement design, factoring in climate, subgrade, and materials. Taking in more factors makes for a greater pavement design to match the environment for which its constructed.
With each passing year, the technology gets better and more cost effective. This can help these projects be rehabilitation work rather than reconstructing the entire roadway. And with rehabilitation work comes designing the roadway to make it better and safer for drivers in the communities.
Designing the Road
Rehabilitation projects are in-depth, allowing for opportunities to improve the safety of a roadway or even the aesthetics: landscaping, streetscaping, upgrades to intersections, crosswalks, sidewalks, and utilities.
However, a critical factor is understanding the current and future needs of the roadway.
“Initially, getting an understanding of the current and future roadway usage, traffic volumes, and ESAL loading is important in estimating the remaining service life and projecting the future service life of the roadway,” said Whitney. “Considering the type of roadway and current design standards for that roadway are essential in determining if any horizontal or vertical changes are needed in the roadway before proceeding. Investigating the pavement conditions, through non-destructive testing and pavement cores to determine subgrade conditions is also key to estimating remaining service life of the roadbed.”
Understanding existing conditions is critical. This involves surveying the pavement to determine its condition, surveying the existing drainage system to check at what level it is functioning, checking roadside features (which can include barriers, guard rails, and impact attenuators), inspecting structures such as bridges and retaining walls, and inspecting other highway systems, which can be lighting and ITS.
Evaluating the existing conditions is also critical. The roadway and the supporting features are evaluated against current criteria, as well as criteria of the year it was constructed. Contractors will get answers to questions such as: how much life is left in the current pavement? Does the roadway effectively drain? Do the roadways allow current vehicle loadings? Do the roadside safety features protect todays vehicles?
Roadways degrade over time due to a host of reasons, such as traffic usage, erosion, improper draining, and environmental causes. Vehicles using a road can cause stress and strains on the pavement layers and sub-grade which deteriorates the road over time. Rainfall affects the amount of surface and sub-surface structure. Excess water can damage the roadway, which is why drainage is such an important aspect of road design.
Lastly, determining an approach will show if rehabilitation work is needed. A cost-benefit analysis also will show if rehabilitation is the solution. If rehabilitation is more beneficial than reconstruction, design will move forward with determining the best repair option for the roadway.
When the DOT and contractor have all the data, then it’s strategy time. Hamlet’s strategy is short and simple. “Maximize the extension of the life of the facility and roadway safety while minimizing cost,” he said. Makes sense: taxpayers want the best bang for their buck and DOTs don’t want to make more work for contractors and citizens who are using the roadway while utilizing the best strategies for repairing the roadway.
The work put into a project needs to last. That’s why understanding the future needs for the corridor is so crucial. Assessing the site to improve the communities needs and provide the service life necessary to justify the cost of improvements is vital to these projects.
“Given the limited resources many DOTs have, rehabilitation is the right approach if the roadway is salvageable and the future needs are not changing significantly from its current usage,” Whitney said.
Utilizing the time and resources at their disposal, contractors want to get the job finished. And with the boost in funding from the IIJA, DOTs want to utilize every cent to ensure that project needs are met, as well as the needs to the surrounding communities.
Jim Kreider, the director from Branch Civil explained that road rehabilitation projects can be “completed in a shorter duration, so you see an immediate benefit. There’s no long-term update to that road.”
Minimizing the impact on the surrounding community is huge because no one wants to be stuck in traffic. Rehabilitation is much less time consuming than reconstruction and can be easier on the drivers who use those roads every day.
Road rehabilitation really comes down to the community. In every step of the way, these projects come back to what the people who use them need. Strategizing around ensuring that the roads are safe to travel on, are properly upgraded to fit the needs of today and tomorrow, as well as fit the needs of the community, are all crucial when developing a road rehabilitation project.
Road rehabilitation, in many cases, is the right solution. Not every road can be rehabilitated after years of erosion and deterioration from usage. However, for those roads that need an upgrade, and aren’t in complete disrepair, rehabilitation is the way to go.
Improved technology, lower cost, and masterful strategy for the design and execution of these projects are a perfect storm of competency. Drivers don’t have to wait hours in traffic because of roadwork. Communities can thrive through the infrastructure that is put there to help with their daily needs. And now with the rollout of the IIJA, states are more inclined than ever to fix the problems with their aging road systems. R&B