La Pólvora tunnel is the key structure of the Southern Access to Valparaiso, allowing trucks to leave the port and head directly south, without having to pass through the city centre.

The tunnel, which runs through a large part of the Playa Ancha hillside, has been catalogued as one of the most modern in Latin America.

The tunnel is almost 2,200 metres long, with a single two-way carriageway. It was built by Ferrovial Agromán Chile S.A.
Field equipment:

• 30 fixed TV cameras
• 9 mobile TV cameras 
• 24 blade/arrow signs
• 10 speed-limit signs 
• 10 PMV 1 Line 
• 2 PMVs 3 Lines + 1 Graphics 
• 49 SOS posts 
• DAI system 
• 4 red/green traffic lights 
• 20 PLCs 
• 3 ERUs 
• 5 measuring points 
• 12,000 m of 16-multimode fibre optic cable 
• VHF and FM tunnel radio system 
• 6,500 m of radiant cable (Leaky Feeder) 
• 41 PA loudspeakers 
• 5 CO detectors 
• 5 opacity detectors 
• NO detector 
• 62 open-door sensors 
• 3 watertight-level sensors 
• 2 water-flow switches 
• 5 detectors of vehicles in emergency bays 
• Lighting control 
• Ventilation control 
• 2 electronic headroom indicators 
• 2 pressure gauges 
• 4 luminance gauges 
• Linear fire-detection system (fibre laser)
  • 44 manual alarm stations 
  • 22 smoke and temperature detectors 
  • 5 sound alarms with strobe lights

Control Centre equipment:

• SGT server
• SOS server 
• 2 TV keyboards 
• PA keyboard 
• 3 client monitoring PCs 
• Client viewing PC 
• 8 TV monitors in control room 
• 6 TV monitors in visitors room 
• Corporate IP telephone network

Particularly worthy of mention is the ventilation-control system implemented by SICE, divided into sanitary and fire ventilation.

For sanitary ventilation, the system automatically regulates the triggering of the six axial jet fans at each of the tunnel mouths according to the environmental variables measured by the CO, NO and opacity sensors. There are five levels of permitted pollution plus one tunnel-closure level. At each of these levels a certain number of pairs of accelerators are switched on in the same direction as the wind in the interior of the tunnel and according to the traffic intensity (“piston effect”).

For fire ventilation, when the fibre-laser system detects a fire inside the tunnel, it triggers the fans, smoke extractors and louvers installed on the tunnel roof:

• If the fire occurs at one of the mouths of the tunnel, the six fans at the opposite mouth drive air through the tunnel to expel any noxious gases generated by the fire. 
• If the fire occurs inside the tunnel, the system opens the three louvers nearest to the site of the fire, while the extractors at the ends of the tunnel begin to suck any noxious fumes and expel them outside the tunnel. To facilitate evacuation procedures, the fans at the tunnel mouths drive air in one direction or the other, depending on the air speed and direction inside the tunnel at the time of the fire, attempting to achieve a constant air speed inside the tunnel of 2.4 metres per second, which corresponds to the rated speed for the system for the continuous aspiration of 160 m3 of air per minute.