Monitoring of the LTPP (Long- Term Performance Program) sections (100 m long) started in 1984 on commission of the Swedish Road Administration.
The objective of this project is to collect and deliver high quality road data primarily for use in the development of performance prediction models. The aim is primarily to focus on road deterioration caused by heavy traffic.
The project started with a limited amount of sections but, in 2015, the number has increased to 690 sections distributed over 65 sites. All sections are included in Sweden’s national road network. The following activities are included in the monitoring programme:
- Distress surveys. Annual surveys are carried out by walking over the sections. During the survey all distresses and surface defects are recorded. The grading of the distresses and defects are based on a national distress manual.
- Calculation of an annual crack index. The index is calculated from the type of crack, crack distress grade and crack propagation and is included, in table form, in the database.
- Road surface monitoring. Financial restrictions limit the monitoring to every second year. However, rut development and longitudinal unevenness follow a relatively linear trend, so monitoring every second year is considered acceptable in this case.
- Measurement of the bearing capacity (KUAB-FWD). The capacity is measured on all new sections and after any maintenance measures.
- Cross section profiling is no longer carried out.
- Collection of climate data from SMHIs automatic weather observation stations.
- Collection of traffic data normally every fourth year.
- Quality control check of all collected data before being entered into the LTPP-2015 data base.
Delivery of the updated database to the Swedish Transport Administration have been published in 2016. A contents guide and user manual is also available. The updated database, LTPP-2015, is available via www.vti.se. Examples of monitoring and condition development are given in the appendix section of the project report. An annual separate database with digital photos is also available.