Route Of Lot Two:
- This lot starts from Doab-Shahrestanak to Pol-e- Zangouleh with an approximate length of 22 km and consists of two main lanes and a slow lane in the slopes.
- The maximum road slope is 6 percent and the minimum radius of arcs is 450 meters.
- By executing this section, the length of the current Karaj-Chalus road will be shortend by about 5 km.
Main operational volumes of lot Two on Round Trip Basis:
- 43 Tunnels with 39.4 Km length
- 20 Bridges with 2.4 Km length
- 2.5 Million m3 earth works
- 76% of the route consists of tunnels
- The longest bridge: 321 meters long
- The longest tunnel: 6400 meters long
Alborz Long Tunnels:
- The longest Tunnels in this lot are Alborz twin tunnels with 6400 meters length each and one access tunnel.
- Considering the special geological features of Alborz Mountain, excavating Alborz access tunnel with high accuracy and sufficient identification was required.
- Therefore a TBM machine was purchased and used for the excavation of the Alborz access tunnel.
The Eastern Alborz Tunnel is Under Operation:
- The Alborz Tunnel Complex is comprised of 34 main, service, and connecting tunnels. Apart from the two main tunnels, each of which is 6400 meters long this Complex has a third tunnel between the two main tunnels that was used as an access tunnel for excavating the two main tunnels and after operation it is used as an emergency service tunnel .
- Each of the Alborz Tunnels’ tubes are connected by 9 separate cross headings as rescue tubes for vehicles. The main tunnels are also connected to the service tunnel via 22 small tubes which are used to evacuate the passengers from main tunnels in emergency.
- Another unique feature of Alborz tunnels is the semi-transverse ventilation system. The second ceiling of this tunnel, 13-kilometer long in total, is equipped with automatic valves and powerful jet fans to ventilate the main tunnels. These valves open when needed, such as the times of firing. In such an event smoke is emitted and the air pressure is managed to prevent the spread of fire and polluted air throughout the tunnel.
