By: Ulrich Hermanski
Roads are the principal part of any global transportation network and thus an essential part of a modern economy. An up-to-date and complete transportation infrastructure is of the utmost importance for a country’s competitiveness.
By 2050, the world population is expected to rise from 7.5 billion today to 9.7 billion. With the population and number of vehicles growing exponentially and a lack of historic investment into existing and new road networks, there are significant pressures to improve infrastructure across the globe.
Today, the world invests some $2.5 trillion a year in the transportation, power, water and telecom systems on which business and populations depend. In reality, this amount continues to fall short of the world’s expanding needs.
Research clearly demonstrates a continuing decay of the international road network. Once the routes dilapidate, traffic jams will inevitably follow. Bridge closures, especially, have a dramatic effect: long detours and traffic congestion test everybody’s patience. It is clear that much more than only the backbone of the traffic is endangered: in such situations, mobility, quality of life, and economic competitiveness are at stake.
Therefore, the industry is under pressure to find innovative, cost-effective ways of working, to limit the amount of time roads are closed, improve safety for road workers, and make road networks more efficient.
Resurfacing is an effective way to maintain existing roads. However, traditional methods can be both expensive and time-consuming. To date, the greatest difficulties associated with construction on existing roads and in flowing traffic include:
- Data acquisition with very low point density
- Inaccurate quantity of surveying
- Lane closures required for data acquisition long before the start of milling work and therefore, additional traffic disruptions
- Low level of occupational safety when surveying in flowing traffic
- Achieving the required longitudinal and transverse smoothness.
Aspects of safety and accuracy, as well as quality and cost, are taken into account in an overall working process. To this end, the SmoothRide road resurfacing process defines seven individual steps that have been coordinated and integrated for the first time in a comprehensive system.
Although the integrated SmoothRide system developed by Topcon can prove to be beneficial for road contractors, it cannot eliminate the efficiency or quality issues caused by incorrect practices. Before the system is installed and used, the technical principles of asphalt paving therefore not only need to be known and understood, but also implemented in the construction process.
A smooth, level, and safe road surface is the calling card of every asphalt construction company. Asphalt paving is teamwork. All employees involved in the planning and paving process must receive in-depth training to ensure correct results. With a well-trained paving team and the integrated SmoothRide system, a team can produce quality asphalt pavements. This results in significant increases in efficiency, perfect surfaces, and long road service lives.
All of the above goes for airport runways too—the more travelers and freight, the more use of the runways and their maintenance are needed. One of the main time drains on projects is that roads or runways have to be closed for surveys to be carried out. Current survey methods of data collection involve a surveying team collecting a point around every 15 meters, which do not provide a high density of data. Additionally, having a low density of points makes it difficult to smooth out the cross slope and main axis slope. Technology such as automation and mass data collection are key to speeding up processes.
As with roads, it is essential that runway renovations are dealt with quickly and efficiently, causing as little air traffic disruption as possible. Europe’s third largest airport, Frankfurt, had to resurface Runway West. The airport manages more than 60 million passengers per year and 50% of these depart from that runway. With the strip being in such high demand, closing it for maintenance was a challenge. Any work therefore needed to be carried out quickly, without errors. Also, the high-security on site needed to be taken into account, which meant that every person, every truck, and all the materials had to go through Customs each time they had to enter or leave the job site. Furthermore, the project required six milling machines to be used simultaneously, which meant that optical instruments, including lasers and total stations, could not be used.
The first stage of resurfacing using SmoothRide involves mobile mapping using vehicles that scan at speeds of up to 80 kph, delivering an accurate depiction of the runway surface. The scanning process results in the creation of a precise map of the entire surface at normal highway speeds. Data is collected every 20 cm in the initial survey and therefore provides high-density, accurate information. This process ensures all imperfections in the old runway surface are recorded. This data is utilized in the paving and compacting process to vary the levels of the asphalt required to create an evenly flat surface.
The next step is to create a design that meets the specifications required. Using intuitive software, the millions of data points can be managed and optimized. Following this, a transfer is carried out into the Topcon Resurfacing software module, which has features required to meet smoothness and cross slope requirements, while adhering to any minimum or maximum thickness specified for the project. The design is then sent directly to the machines, allowing for milling and paving to commence immediately.
While traditional methods of surveying use 2-D machine control, SmoothRide is equipped with 3-D machine control. The milling machine’s position is determined by GPS and the height difference for milling is measured with sonic sensors and internal machine sensors. This means that at every position the machine controls the milling depth with millimeter accuracy. Also, with automated variable depth control, milling can be carried out exactly to the specified depth, allowing for mill to fill optimization, and a smooth surface for the paver to follow. Through managing material usage, a uniform thickness of paving is achieved, improving accuracy and allowing for the job to be completed in one go, saving time and reducing cost overrun. With 14 cm milling depth, it was essential that 3-D machine control was carried out. The 3-D model allowed for accurate measurements to be transferred to a screen in the milling machines’ cabs, which gave drivers guidance on the exact amount of material to remove.
Utilizing the same job files generated from milling and paving machines means that operators can know exactly when and where to compact, which prevents over-compacting and therefore increases the efficiency of the process. It is the advanced heat sensors that help to inform where to carry out compaction. While compaction processes are active, rollers collect as-build data on the build surface and additional measurements are not required.
The Frankfurt Airport project was carried out in just five days; 45,000 m2 of runway was resurfaced. The runway is also ultra-smooth. Not only is a smooth runway more comfortable for the crew and passengers, it also reduces the wear on planes, increasing their longevity and reducing repair costs.
About The Author: Hermanski is chief marketing officer for Topcon Positioning Group.
