Viktoras Vorobjovas

Correspondence of horizontal and vertical alignment with safe driving conditions on low-volume roads

Since 1998, when the Gravel Roads Paving Program was started on the regional roads of the Republic of Lithuania, the length of gravel roads has shortened by 13.4% after reconstruction. It was discovered, however, that after reconstruction, 4.7% of gravel road sections became potentially dangerous. A disadvantage that was noted during implementation of the Gravel Roads Paving Program was a slightly changed or entirely unchanged horizontal alignment of the roads. In addition, after a gravel road is paved, the speed limit increases from 70 km/h to 90 km/h, as is allowed by traffic regulations, although the design speed of regional roads is 70 km/h and the road alignment was planned for that design speed. The horizontal alignment of 30 regional roads was investigated to assess the compatibility of horizontal alignment elements and their correspondence with traffic safety and to study the sight distance in vertical alignments. It was determined that compatibility of the horizontal alignment elements of regional roads was sufficient, but the estimated flow speed on these elements was 10 to 20 km/h higher than the design speed. Analysis of the sight distance, the stopping sight distance, and the passing sight distance in the vertical alignment of roads showed that in 90% of the cases, the sight distance was shorter than the stopping sight distance on a tangent.

Performance of Soft Asphalt and Double Otta Seal within First Three Years

Gravel roads play an important role in the transport infrastructure. However, their maintenance (especially the control of dustiness using chemical dust suppressants) is expensive. Besides, the condition of gravel roads results in low driving comfort, longer travelling time, faster vehicle amortization, and so forth. Typically, these problems are solved by paving gravel roads with asphalt wearing layer. However, north countries practice had shown pavement structure high susceptibility to frost due to insufficient thickness of frost resistance layer. The construction of thicker frost resistant layer increases road construction cost by 25% and, in most cases, there is no need to increase bearing capacity by increasing total thickness of pavement structure. In 2012 19 gravel roads were constructed using cost effective rehabilitation technologies—soft asphalt and double Otta Seal in Lithuania. This paper focuses on those two technologies’ performance within first three years of constructed roads exploitation. The implemented experimental research consisted of three parts by evaluating constructed roads base layers bearing capacity; pavement roughness; and pavement distresses and defects. As a result, the acceptable performance indicators were determined for both technologies—soft asphalt and double Otta Seal. Also recommendations for construction and exploitation improvement were defined.

Soft Asphalt Pavement – Solution for Low-Volume Roads in Changing Climate and Economy

In Lithuania, it has always has been an important issue to find durable and cost-effective solutions for paving low-volume roads. The conventional asphalt concrete structures were built using paving grade bitumen with the penetration of 70/100 or 100/150 over the recent 20 years. The performance of those pavements was satisfactory. As an alternative solution, the use of soft asphalt pavements was proposed. This technology is widely used in Nordic countries. But in Lithuania it has never been applied. Research on the designed soft asphalt mixtures was carried out and the trial on-site sections were constructed. The results of laboratory tests and on-site research were positive and promising. Based on that, the technology could be considered as successfully implemented and good quality was achieved.

Performance of Pavements Affected by Static and Impact Load

Pavements of airdromes, ports and container terminals, logistics terminals, industrial areas, parking lots, waste recycling areas and etc. are affected by static and impact loads. These kinds of loading differ from typical loading of roads. Due to it, pavements affected by static and impact load are design by special models according to the main distresses – permanent deformations and thermal cracking. For this purpose, there are discussed characteristics conditioning performance of pavements affected by static and impact load.