Concept for improving traffic safety at the existing intersection of road I-5 "Kazanlak - Stara Zagora-Dimitrovgrad" with municipal road SZR1187 by introducing traffic organization with a roundabout

The intersection will be converted to roundabout traffic without new pavement being laid – the existing area of the intersection and the built asphalt pavement will be used. Nevertheless, there are sections and zones that need to be asphalted – these are the existing dividing islands in the intersection and the necessary widening of the pavement from the north. For the indicated zones, "local repairs" (LR) or construction of a new structure with asphalt surfacing are foreseen. The new structure will be the same as the existing structure of road I-5 in the section. New structure for the dividing islands and widening of the pavement from the north: Dense asphalt – type I “A” with polymer-modified bitumen - 4 cm Loose asphalt (binder) with polymer-modified bitumen 4 cm Biaxial geogrid - openings 25/25mm 100/100kN/m (for reinforcement and crack control) Bituminized crushed stone for base 15 cm Rock material with selected grain size 0-63mm, min 40cm (laid in two layers) Earth bed – excavation of unsuitable material E0 eq. min 45MPa Before laying the bituminized crushed stone, a bitumen spray is applied onto the compacted base of rock material 0-63mm – first bitumen spray with cationic bitumen emulsion 1200-1500 g/m2 (TS API 2014 - section 5700). Before laying the geogrid and the layer of loose asphalt - binder, a bitumen spray is applied onto the laid layer of bituminized crushed stone and the milled strip of road I-5 – existing layer of bituminized ballast - second bitumen spray - cationic bitumen emulsion 800-1000 g/m2 (TS API 2014 - section 5800). Before laying the layer of dense asphalt, a bitumen spray is applied onto the laid layer of new loose asphalt - second bitumen spray - cationic bitumen emulsion 800-1000 g/m2 (TS API 2014 - section 5800). The new dense asphalt will be laid over the entire area – LR and the area with re-asphalting. In the areas with re-asphalting, the dense asphalt is laid on top of the old asphalt and the bitumen spray cannot be 500-700g/m2. The connection between the new and old pavement is executed according to the attached detail. In order to offset the joints (not to be one above the other) in the different asphalt layers, the existing asphalt is milled in steps as follows: At a distance of 60cm from the outer edge of the existing asphalt, the asphalt layers are milled to a depth of 8cm; At a distance of 30cm from the edge of the carriageway, the remaining asphalt is milled down to the level of the existing crushed stone base; (At these offsets, the geogrid - roll/tape width 1.2m) (*) overlaps 60cm from the "edge of the carriageway" into the existing asphalt of road I-5 and 60cm into the new structure being built. After excavation in the dividing islands and surrounding terrain, the new structure is executed. On top of the new layer of bituminized crushed stone, including the milled part of the republican road's structure along the entire length of the contact zone between the old and new pavement, a biaxial geogrid with openings of 25/25mm and strength of 100 kN/m in both directions is installed. The width of the geogrid is 1.2m. The geogrid is installed for reinforcement and crack control in the zone of the longitudinal joint between the existing and new structures. For the entire intersection / in the active zone of the intersection / the central circle and the lanes at the entrances and exits, "re-asphalting" will be carried out. This repair will include cold milling of the existing asphalt to a thickness of 4cm and laying a new layer of dense asphalt on the milled area with a thickness of also 4cm. The roundabout will be executed only with horizontal markings in combination with road elements – "raised kerb for roundabout with bollard" and "signal bollards". The horizontal markings of the new roundabout will be executed in white color in accordance with the requirements of Ordinance No. 2 - Art. 5. (Amended - SG, issue 34 of 2015, effective from 18.05.2015). Vertical signage will be executed with new road signs of size III with reflective film class "RA2", when the sign is mounted on the right and with film class "R3A" and "R3B" for mounting on the left and above the traffic lane. Before starting the construction and installation works, the contractor must prepare a project for temporary traffic organization...