The tasks of a quality control consultant in maintenance contract work

Road Consulting Oy has comprehensive experience from quality control of summer and winter maintenance of area contract work. We have acted as a quality control consultant in Lapland’s road district’s quality control for winter maintenance in 2006, and in point-based quality control for Häme road district in 2007-2008.

At the moment we control 15 maintenance contracts in the HTUV inter-municipal cooperation area, 18 maintenance contracts in the KSK inter-municipal cooperation area and 20 maintenance contracts in the OL inter-municipal cooperation area.

Random sampling control is mainly done when the weather changes outside of office hours.

Issues checked in random sampling control:


  • measuring of friction

  • measuring of smoothness and the thickness of the ridge

  • measuring of the snow cover

  • tidiness and condition of rest stops

  • condition of traffic signs

  • surface condition of gravel roads

  • side slope of gravel roads

  • carrying out of regular jobs at specific times

  • official tasks as additional work

Our references include e.g.

  • The Finnish Transport Agency

  • ELY centres


Road Consulting Oy has a KUAB FWD 50 falling weight deflectometer in its use. Similar devices have been used for capacity carrying surveys of Finland’s common road network since 1987.
The bending of the road surface describes how the road’s structural materials behave under strain from traffic. This strain caused by traffic loads is simulated with a falling weight deflectometer which measures the force targeted to the surface of the road and the bending caused by the strain. The duration of the strain caused by the falling weight deflectometer on the road structure is c. 22 ms, and it represents well the strain impact of heavy machinery traffic.
The interval of measuring points with a falling weight deflectometer can be freely chosen, and usually an interval of 50 meters is used. From the measuring results, the carrying capacity qualities of the road or street are calculated with calculation software, revealing possible deficiencies in the carrying capacity of structures. With the measuring software, the required increase in the thickness of structures in order to reach the carrying capacity requirements can be calculated for carrying out additional or improvement work.
A carrying capacity survey is a quick and low-cost way of ensuring the carrying capacity of the target.

Uses for the falling weight deflectometer:
Carrying capacity survey to gather initial information for planning




  • in a general road network

  • on streets

  • on private and forest roads

  • on yard and parking areas

Carrying capacity survey for quality control

  • paving jobs

  • land improvement jobs

  • new roads and streets

Our references include e.g.

  • Private road maintenance associations

  • Road hosts

  • The Finnish Transport Agency

  • ELY centres

  • Metsähallitus

  • Forest centres

  • Consulting companies

  • Cities, towns and municipalities

  • Forest companies


A ground-penetrating radar survey is a geophysical survey that does not break the measured materials. The survey is based on electromagnetic waves sent to the road, soil or water on a radio wave frequency. Some of the sent waves return back to the recording unit when encountering an electric barrier layer, such as the surface of a different structural layer, and some of them continue until the next layer. When this is done as a continuous survey, it is possible to get a continuous profile, i.e. a vertical cross-section, of the measured target. The frequency range used in the survey is 10–3000 MHz.

This survey is used on roads and streets to determine the thicknesses of the current structural layers, and partly also to determine their quality. This information is utilized generally in structural improvement planning and quality control for a newly constructed road.


In soil studies, it is used to determine soil types and rockheads or water tables. In water system studies, the status and soil type of the bottom of a watercourse can be determined with this survey.

Roads and streets are measured with a 1–2,5 GHz air-coupled antenna (pavement radar) with a depth range of c. 0.8 m and with a 400–600 MHz ground-coupled antenna (structural radar) which can reach a depth of c. 3.5 m depending on the ground soil. During the survey, the targets are video recorded, and accurate coordinate information and travel information is collected for accurate locationing of the survey result.


The ground radar survey result is used to determine the thicknesses of the different structural layers, the soil type of the ground soil and discontinuities in the structure, such as mass replacements. The results can also show the location and position of steel nets installed inside the road as well as point-based targets, such as drums, pipes and cables.

This survey is also often used for quality control of the pavement and the construction of the whole structure. This includes determining the air void in the pavement, the thickness and position of the constructed layers and possible mass replacements or mass displacements.


Based on the ground radar survey result, sampling can be targeted to problem spots or discontinuities. With the help of the sampling, the interpretations of layer thicknesses and soil type definitions can also be confirmed.


Inventorying of pavement damage creates a basis for examining the condition of roads, streets and footpaths.


Pavement damage information is a starting point for planning structural improvement of a road or street or for programming a re-pavement.

Damage inventories can also be conducted for footpaths in addition to the road and street network.

Based on the damage information, it is possible to determine fairly reliably the factors that caused the damage.


Inventories of general road data refers to the inventorying of the following types of data:


  • basic inventorying

  • inventory projects

  • inventories related to maintenance jobs

  • inventories of road markings

  • inventories of visibility

  • inventories of ruggedness

  • separate data recording tasks

  • inventorying of the condition data of gravel roads

  • damage inventorying of footpaths

  • photographing service of the road network


The basic inventorying includes collection and registering of data according to the inventory instructions of Tierekisteri pertaining to announcements received by the ELY centres of new and improved road sections.

Inventorying projects include comprehensive inventories for one or more types of data for the region or network, determined on a case-by-case basis. The service can also include registering of the inventoried information in Tierekisteri.

Inventories related to maintenance jobs cover the inventorying of devices in the road area or structure (e.g. traffic signs, drums, railings) and delivering the information to a database defined by the client.

Inventorying of road markings covers the inventorying of road markings, checking their quality and delivering the inventory information to a database defined by the client.


Inventorying of visibility involves defining the visibility percentage of a road section.
The goal of the inventorying of ruggedness is to gain information about the relative height position of the break points of the road’s gradeline relative to the beginning point of the road section.

The inventorying of the condition data of gravel roads refers to inventorying of frost damage to the foundation, the level of service and the structural condition of gravel roads, as well as delivering the inventory information to the client in accordance with the assignment.


Damage inventorying of footpaths includes the inventorying of the pavement of footpaths for cyclists and pedestrians. Pavement damage is inventoried for the whole width of the road and the data is recorded in a road condition register.

The photographing service of the road network means taking photos of finished road sections and updating road photos according to the maintenance cycle in accordance with the requirements of the digital photographing of the road network.

The inventories are done on the road by examining the targets with the naked eye. The target data is linked to the address information system of Liikennevirasto (The Finnish Transport Agency). The data inventorying can also include photographing of the targets.


The different phases of the inventorying are:

  • the equipment and required software/information are prepared for inventorying

  • a survey plan is created

  • the inventory is conducted according to the survey plan

  • the lengths of the inventory data are calculated

  • overlaps and other such important issues are checked

  • the inventory data is delivered to the client

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