Niayesh Tunnel

Project implementation

The project’s branches in excavating and pouring concrete

• Tunnel excavation with the diameter of under overburden less than the tunnel's diameter in the length of 2.5 km in the Alluvium soil and urban area is one of this project's Characteristics. In tunneling it is common to excavate under 2 times of the tunnel's diameter overburden.
• Tunnel bifurcations excavation with overburden while the section width is and its height is – the same height as a 6-storey building – the bifurcations are the largest excavation section in the world with the area in alluvium soil.
• The tunnel excavation was controlled by surface and underground instruments. This job not only caused excavation without any collapse and human casualties but also caused 13 million dollars decrease in costs of initial lining. In addition, due to increase in excavation speed, millions of dollars has been saved.
• Final lining thickness is in this tunnel which it is typically in previous tunnels.
• Using special creativities, final lining reinforcement has done with industrial method which caused saving a large amount of money.

• The latest Europe safety standards have been engaged in the Niayesh tunnel. Emergency exit ways are prepared in each 250 m between tunnels and for each 500 m there are some access to the ground surface in Kordestan highway, Vali E Asr street, Nonahalan and Golshahr streets. These emergency exit ways are recognizable with green signs on the tunnel walls, green LED lights and panels.
• In these tunnels there are emergency rooms every that provide a connection with central control room for tunnels users. These rooms are equipped by fire-retardant doors, which can withstand fire for one hour.
• This tunnel's firefighting system is supplied by water and contains two main lines in each tunnel. One of them is next to the high-speed line for firefighting machine supplies and the other one is next to the low-speed line and is connected to firefighting panels in each 45 m for benefit of users during incidents. In those panels there are two fire extinguishers.
• In this tunnel there is a longitudinal ventilation system. There are 63 jet fans with 37.5 KW rated power. This system cables are resistant to fire up to 1.5 hour with the temperature of 950 °C. in emergency situation there is considered an air exchange station.
• For high-voltage power lines system in this project, cables have been inserted. This project has two connections: one from municipal power and another for the emergency situation, a power house with 6 MW power.
• Due to controlling installed facilities in Niayesh tunnel, the ITS has been used according to the newest Europe standards and technology. In this system related signals would be transferred to equipment in control room and software will process them and then related scenario of each manner like fire, accident or.... would be performed.

  ITS

1. Traffic control system including traffic signs, lane control system, variable massage sign and lights.
2. Video monitoring system including automatic accident identifying and processing cameras and moving cameras.
3. Ventilation control system of jet fans are able to order to jet fans based on information gained from air pollution sensors and visibility sensors.
4. Fire announcement system through LHD cables.
5. Fire retardants doors access tunnels to ground surface and emergency exits for cars would be opened with hydraulic motors by control room operators and make the possibility of cars conduction from the tunnel with fire to the safe tunnel.
6. Emergency room doors.
7. With the start of the radio system of the tunnel, firefighting, emergency, police and the tunnel's operator wireless system would be activated. And through ITS, related radio messages would be published on 4 available radio waves for cars in the tunnel.
8. Announcement system is able to publish necessary points in addition to radio system via speakers installed to tunnel.
9. All emergency exit signs, tunnel escape route signs, SOS, tunnel route control signs, VMS, Tunnel information signs and lights.
10. Flood detection sensors in the entering and exit ramps.

• This tunnel's ITS controls light intensity considering the outside Brightness.
• ITS system software performs different scenarios based on data are gained from installed sensors and switches. For example, in a fire situation according to fire location which is identified by special cables, required jet fans would start to work, emergency doors would be opened at risk area and cameras would be focused on the incident place, then VMS would show escape ways. Other scenarios would be performed by ITS system in case of accident, flood, power outage etc.
• According to its installed safety system, ventilation facilities and firefighting system, Niayesh tunnel is one of the safest urban tunnels in the world.