Sedan 1984 har VTI gjort uppföljningar av observationssträckor för att samla in, bearbeta och leverera data att användas för utveckling av tillståndsförändringsmodeller. Inriktningen är i första hand fokuserad på den nedbrytning som orsakas av tung trafik. I projektet (LTPP) har antalet provsträckor ökat efterhand och 2013 uppgick antalet till 681, alla i det statliga vägnätet. På grund av en snävare budget har antalet nu minskat och inför 2014 kommer 302 sträckor vara aktiva. LTPP-aktiviteter är insamling av data från olika källor, som exempelvis besiktning av samtliga aktiva sträckor till fots, mätning med vägytemätbil, fallviktsmätning på nya objekt, klimatdata från SMHI:s väderstationer och trafikdata från Trafikverket. Insamlad data bearbetas, kvalitetskontrolleras och samlas i en databas, den senast aktuella benämns LTPP-2013. Leverans av den uppgraderade databasen sker till Trafikverket under år 2014. Den uppdaterade databasen, LTPP-2013, kommer att vara tillgänglig via www.vti.se. LTPP-databasen har dels använts till att kalibrera modeller för bland annat spårbildning, sprickbildning och beständighet och dels till att validera tillståndsutvecklingen och åtgärdsbehovet. Fler exempel på användningsområden beskrivs i detta notat.

The objective of this project is to collect and deliver high quality road data primarily for use in the development of performance prediction models. Monitoring of the LTPP sections started in 1984 on commission of the Swedish Road Administration. The aim is primarily to focus on road deterioration caused by heavy traffic. The project started with a limited amount of sections but, in 2013, the number has increased to 681 sections distributed over 64 sites. All sections are included in Sweden’s national road network. During 2014, 302 sections distributed over 32 sites will remain active. An example of use is that in 2000 VTI was commissioned by the Communications Research Board (KFB) to develop crack initiation and propagation models caused by traffic loading. The procedure was similar to the approach applied to the development of crack models used in the PARIS (Performance Analysis of Road Infrastructure) project. The basis of these models was founded upon data collected in this project. Another example is that VTI, commissioned by the then National Road Administration, performed validation of the software tool used for the calculation of road bearing capacity - PMS Object. The first phase included valuation of new construction and was carried out during 2003 and 2004. The second phase evaluated reconstruction and was completed at the start of 2005. In addition, a prediction model for rut depth caused by heavy traffic has also been developed and a report was published in the beginning of year 2007. A current VTI project aims to develop a calculation tool for life cycle cost assessments of various design options in the planning and design of roads. In order to predict future maintenance requirements for various designs options, condition development models are being used to forecast condition and cost requirements during the roads lifecycle. The LTPP database has also been used to help calibrate models for conditions such as rutting, cracking and durability. It has also helped to validate condition development and the need for maintenance action.