The Finnish Transport Agency, the Lapland and Central Finland Centres for Economic Development, Transport and the Environment and Roadscanners Oy launched a 10-year research and development project called PEHKO in order to increase the productivity of paved road management in Finland at the beginning of 2015. The aim of the project is to stop increasing deterioration rates on the Finnish paved road network by means of the latest technology and to lengthen pavement lifespan. This would lower the annual costs of paved road maintenance considerably.
“The idea is to study and eliminate the reasons for pavement deterioration”, explains Head of Unit Jari Mikkonen from the Central Finland Centre for Economic Development, Transport and the Environment. The project involves studying the life-cycle costs of paved roads and the factors that affect them. The goal is to identify ways to improve the condition of paved roads at lower annual costs. The key is to find solutions to stop increasing deterioration rates on the Finnish paved road network and to lengthen pavement lifespan.
New innovative technology
The studies are based on highly precise underground measurements and digital modelling. The techniques involved include, among others, deflection measurements, ground-penetrating radar and laser scanning.
“Some of the solutions that were are using are old, tried and tested measurement techniques, but we have also incorporated innovative measuring equipment and digital solutions developed by Roadscanners Oy. They give us even more accurate information on the bearing capacity of subgrade soils, the strength of the structural layers and the pavement and the effectiveness of drainage. We are now able to detect, for example, micro-fractures in road structures and latent dampness in or underneath the pavement”, Jari Mikkonen explains.
Results of pilots: costs down by 12–30%
The PEHKO project is being piloted in Kemi and Karstula between 2016 and 2021. In Lapland, the focus is on paved roads in the Kemi area and major roads in the Rovaniemi area. The pilot in Central Finland covers paved roads in the Karstula area. So far, the roads in the pilot areas have been comprehensively studied by means of TSD, ground-penetrating radar and laser scanning. The studies have identified road sections that are still in a relatively good condition at the moment but that will nevertheless deteriorate quickly unless preventive action is taken to strengthen them. Sections that are in urgent need of repair as well as critical sections have also been identified.
According to Mikkonen, the project has lowered the maintenance costs of paved roads in the pilot areas in Lapland and Karstula by 12–30% based on provisional calculations. The goal is to halve the maintenance costs of paved roads during the 10-year project period.
Slower deterioration by means of consistent paving, steel mesh structures and drainage
Provisional conclusions can already be drawn from the results of the studies. The road sections that become rutted and deteriorate the fastest are those where there are weaknesses in the road structures or subgrade soils.
“Our approach to pavement repairs in the PEHKO project involves first identifying the structural problem areas of each road section, then analysing the reasons for deterioration and finally drawing up a detailed repair plan. Once the road structures and the condition of the pavement are consistent throughout, the entire road is resurfaced. The consistency and thickness of pavement clearly lengthen its lifespan”, Mikkonen explains.
According to Mikkonen, the pilot scheme in Karstula has proven that this method slows down rutting to as little as less than one millimetre per year in places where the figure was previously as high as 8–10 mm. This enables postponing resurfacing by as much as 10–15 years. A thicker, consistent pavement is also better able to withstand new, heavier lorries.
The use of steel mesh to strengthen and even out the structure has also proven effective in the pilot areas. An especially good solution is a regular steel mesh laid at a depth of approximately 25 cm along road sections that are built on weak soil and where there is a lot of heavy goods traffic.
Cleverly targeted and correctly timed drainage also reduces the annual maintenance costs of paved roads considerably.
“Pushing snow further away from the edges of the road early in the spring prevents the melting water from infiltrating the pavement structure and causing permanent deformations. Digging ditches where slush can accumulate at the roadside and removing icy ridges along the sides of roads are effective ways to reduce pavement cracking. Of the solutions discovered in the course of the PEHKO project, this is the most economic and the easiest way to curb maintenance costs”, Mikkonen explains.
According to Head of Unit Jukka Jääskö from the Lapland Centre for Economic Development, Transport and the Environment, drainage needs to be approached more holistically in the future: “A more holistic approach to drainage is vital. Earlier removal of banks of snow from the sides of roads and digging ditches where slush can accumulate earlier in the spring have proven extremely effective, but works during the summer, such as clearing ditches and overflow channels and repairing and improving private access road culverts, play an important role in preventing rutting and wear.”
Rapid deployment of best practices
The Uusimaa Centre for Economic Development, Transport and the Environment has now also launched a PEHKO pilot project for the years 2018–2028. The new pilot scheme began in June around Hyvinkää, and the pilot area consists of a total of 860 kilometres of paved roads. RDSV laser scanning and ground-penetrating radar surveys will be carried out in the pilot area every year. Deflection measurements will be taken using TSD equipment at five-year intervals. The condition of private access roads will also be monitored by means of visual inventories and inspections.
Mikkonen and Jääskö are extremely pleased with the results of the PEHKO project so far. Techniques that have proven successful in the pilot areas, such as removing snow walls and digging ditches for slush early in the spring, have already been incorporated into new road maintenance contract templates.
Important international recognition for Roadscanners and the PEHKO project
The project team is rejoicing over a significant international award presented to Roadscanners Oy last week. The 70th anniversary gala of the International Road Federation* in Las Vegas on 7 November included an award ceremony which saw Roadscanners winning the highly esteemed Global Road Achievement Award in recognition of its innovative transport infrastructure development practices. This was the first time that a Finnish organisation won the award.
Director-General Kari Wihlman from the Finnish Transport Agency is extremely pleased with the award won by Roadscanners’ and the Finnish Transport Agency’s joint project.
“Research and development are important for us to be able to create new tools for better road management. Digitalisation, in particular, will play an increasingly big role in the future. It is great that our efforts are also getting international recognition. ”
Head of Unit Jari Mikkonen, Central Finland Centre for Economic Development, Transport and the Environment, tel. +358 (0)29 502 4703, firstname.lastname@example.org
Head of Unit Jukka Jääskö, Lapland Centre for Economic Development, Transport and the Environment, tel. +358 (0)29 503 7574, email@example.com
About the PEHKO project
About Roadscanners’ win
About the Global Road Achievement Award
*The International Road Federation is a global non-profit organisation that helps governments to develop better, safer and smarter road networks. The IRF promotes international road infrastructure know-how and education, organises conferences and rewards pioneers in the industry. The organisation is headquartered in Washington, DC and supported by regional offices throughout the world. The IRF has been serving a network of public and private sector members in more than 70 countries since 1948.