Allocation and repair methods for surface repairs
Allocation of repair work
By making use of the road condition measurements and inventory results and the forecasts based on them, planners are aware of the road sections that need to be repaired. Information on repair needs can also be obtained from the regional coordinators of the ELY Centres and from road users through the feedback systems of the Finnish Transport Infrastructure Agency and the ELY Centres.
The busiest roads have the highest priority
For paved roads administered by the state, the repair category is set according to the importance of the road. When the available money does not allow for the repair of all sections that are in bad condition, the repair categories are used to allocate the resources available for road surfacing.
Safe mobility is ensured throughout the road network, but in accordance with national policy, the focus of road surface repair work is the busy main roads. The lower-traffic roads are repaired as much as possible.
The road surfacing program shows which locations are to be resurfaced (link to project map https://julkinen.vayla.fi/webgis-sovellukset/karttapalvelu/index.html?locale=fi&config=hankekartta)
The Centres for Economic Development, Transport and the Environment mostly plan the summer resurfacing work during the previous year. Damage revealed during the spring can then be added to the resurfacing programmes. The programmes also take into account possible changes in the price of bitumen. The resurfacing program is expanded or reduced in accordance with changes in the cost of bitumen, which follows the price of crude oil. The resurfacing work takes place in the summer between May and October.
The resurfacing locations are set in a way that seeks to maximise the efficiency of the resurfacing work. It is cheaper to resurface one ten-kilometre section than to resurface ten one-kilometre sections. In other words, it is sometimes more efficient to leave a short section of substandard road for a couple of years until the surrounding sections of the road are also in need of maintenance work.
How is the repair method selected?
The aim is to implement the most cost-effective maintenance at each site so that as much road as possible can be repaired with the money available. At the same time, efforts are made to select a repair method that is appropriate for the life-cycle of the road surface in question. Resource scarcity and high efficiency requirements have led to innovations that save natural resources, such as the recycling of surfacing materials.
The selection of the repair method depends on the volume of traffic, the nature of the damage, the previous surface and repair method, and other environmental factors.
The selection of the properties of the surfacing material is also an essential part of repair planning. The asphalt surface is made of aggregate and bitumen, and the properties and alloy ratios of these determine the surface properties and durability of the final road surface. The most suitable materials are selected for each location.
Recycled road surfaces
Recycled asphalts are coatings which contain a significant amount of ground (previously used) asphalt. Recycling old asphalt saves raw materials, meaning that their use both saves money and is also more environmentally friendly. The fresh recycled road surface looks and functions like a new surface. The service life of the recycled surface is shorter, but since it has a lower annual cost (cost per year of service life), it is usually chosen whenever technically possible.
On low-traffic roads, the road surface may last for decades. On the busiest roads, on the other hand, studded tyres can wear ruts into the road within a few years. These ruts affect the comfort of driving, but above all they pose safety risks. In wet weather, the risk of hydroplaning increases if there are deep ruts in the road.
In locations where the only problem with the road surface is ruts caused by studded tyres, a cost-effective alternative procedure is rut patching. In this procedure, materials are saved by only resurfacing the areas around the ruts.
It is a better to patch individual potholes and cracks rather than resurface the whole section. The aim of the patching is to maintain the road surface in a condition satisfactory for traffic use and, at the same time, to postpone the resurfacing work to a later time. If patching is done in time, it helps to prevent the damaged areas expanding and becoming dangerous. Patching is therefore part of cost-effective and environmentally friendly road surface maintenance.
Permanent, well-implemented repairs are long-lasting and do not affect the road user's driving experience. Appropriate patching methods have been developed for different types of damage and different road conditions. However, it is sometimes necessary to repair the damage quickly in order to keep the road safe and operable. If road conditions are poor in such situations, the repairs will not be of good quality, and the same location may have to be patched again later on.
The problem with low-traffic roads is that there are many situations where it is not possible to resurface the road when this would be needed. In such cases, the road surface must be kept operable even where this would not be technically or economically justified.
Sometimes damage to the road surface is caused by problems in the base of the road. In such cases, resurfacing is not enough, but instead the structural problems need to be repaired. If the structure is not strengthened, the same surface damage will quickly reappear. Sometimes it is possible to make do with less extensive measures, such as adding steel meshes under the surface or adding crushed rock to the depressions in the road. Sometimes, however, extensive measures are needed and whole structural layers must be replaced. Improving the structure usually also requires more detailed planning as well as surveys to support the planning work.