Overlays and road rehabilitation projects represent the majority of spend in most U.S. states today. According to the American Society of Civil Engineers (ASCE) 2017 Infrastructure Report Card, one out of every five miles of highway pavement is in poor condition and roads have a significant backlog of rehabilitation needs.
While Capitol Hill wrangles over a plan to spend big on infrastructure, repairing the roads that already exist is a top priority for Departments of Transportation (DoT) and, some say, could save more money for tax payers than incentivizing the private sector to bankroll revenue-generating infrastructure projects such as toll roads.
Part of the impetus for DoT’s comes down to basic economics. Getting a fix in place before the road turns ugly can save significant public funds. For example, for every dollar spent now to prevent pavement deterioration saves $8 down the line. As you can see from the chart below, road preservation can cost as low as 20 cents on the dollar per square foot while reconstruction ranges from $3-5 per square foot.
But current roadway rehab techniques and workflows present a perpetual engineering challenge. A study by the Transportation Research Board Committee on Pavement Rehabilitation, which includes representatives from multiple state DoTs, suggests that:
“The state of the practice of pavement rehabilitation is good but can be better…Pavement rehabilitation in today’s environment is always a complex and challenging process. For improvements to continue in pavement rehabilitation technology in a climate of reduced spending by the federal government on research and development activities, the industry will be tasked in the new millennium with a leadership role in implementing innovations in pavement rehabilitation.”
Major innovations are to come, but many are already here and being used by forward-thinking DoTs, such as Caltrans who is leveraging next generation surveying tools and techniques.
But what are the drivers for these new approaches? To understand that, it’s worth revisiting the old (or often current) way of doing things.
The Limitations of Current Approaches to Road Rehab Projects
Historically, DoTs approach road rehab projects with pavement condition surveys. Yet, legacy surveying techniques only provide surveyors with assumptions of overall roadway. With restrictions such as cross sections only every 500-1000 feet, insufficient data to build a 3D surface model, a lack of recognition of existing conditions, surveyors faced uphill challenges and limitations that translate to higher costs during the construction phase dues.
Furthermore, traditional survey methods lack sufficient information to perform intelligent design. They also make it difficult to review all factors at once, such as vertical smoothing, cracks, flapping of roadway, ruts, etc.
Once all the information is gleaned, engineers face a tedious manual process to pull all the information together and make the best design. This suboptimal process of iterative design and re-design creates a missed opportunity for cost and time savings. To add to an already complex process, each engineer often has his or her unique solution meaning that if Engineer A is switched out with Engineer B, then a deviation in the end design is inevitable.
New Tools and Technologies are Key to 21st Century Road Rehab
Recently, the infrastructure industry has made great advances in data collection and 3D terrain generation, via mobile LiDAR data capture. This collection method does not require roadways to be closed for data capture and enables very accurate 3D data capture over several miles per day. Combining this technology with the latest software advances in roadway rehabilitation has created the perfect storm to enable users to have 3D terrain models for all three methods at minimal costs and in minimal timelines.
DLT Solutions recently joined forces with Autodesk’s David Fagerman PLS/RPLS for part one in a three-part DoT webinar that explores how new tools and technologies, such as mobile LiDAR, point clouds, and optimized design tools can create significant cash savings in pavement rehabilitation and reconstruction by optimizing overlay design. David also demos these tools and explores how they assist engineers in developing cost effective and reliable rehabilitation alternatives for pavements.
In the remainder of the series, David will explore further the use of digital design solutions for the construction and maintenance of transportation infrastructure. To watch a replay of David’s Webinar, click play on the video below: