Covering busy (ring) roads near densely populated residential areas is an effective way to take care of the environmental pollution along the whole road. A covering or tunnel however does not solve the specific nuisance due to NOx and nano fine dust. The nuisance is only shifted sideways to the exits of the covering or tunnel and is finally released at extremely high concentration levels.
A short calculation demonstrates the seriousness of the problem: one kilometre of a two-lane ring road with cars and lorries driving 80 km/h equals particulate emissions of 1 gram per second or 3,600 grams per hour. This amount is comparable to the emissions of more than 300 small and medium-sized welding companies with 3 welding locations. The European Emission Guidelines require these companies to install an extraction and filtration system because of the proven health risk.
The current solutions mostly use technology with a very high power demand. For example, heavy-duty fans are used to suck up the polluted air and emit it at high altitude through long and expensive chimneys. Another option is to spread the tunnel entrances away from each other to stay under legal average air pollution levels. These are cost increasing measures which just shifts the problem but don’t solve them. As long as the pollution is not extracted out of the air it will be poured out over the city and cause the well-known health-risks for the city population.
The only truly adequate solution is trapping the air in the tunnels and road-covering structures and filtering it in order to assure a healthier environment even immediately next to a motorway. Existing buildings can be retained and new buildings can be constructed up to the very edge of the road, or in case of tunnels, even over the road. The resulting building ground can easily fund the road-covering structure or tunnel.
Trapping the air in the tunnel has as an extra advantage: the heat generated by vehicles aren’t lost through the exits anymore. After being caught in the tunnel it can be upgraded to heat buildings and tap water and to achieve a more constant surface temperature in the roads leading to the exits and entrances of the tunnel.
HD Clean Tunnel has developed a system which prevents hazardous polluted air from leaving exits from tunnels and motorway-covering structures. Using the air flow caused by traffic and creating air curtains at the tunnel entrances, this energy-efficient tunnel ventilation system locks at least 90% of the polluted air in the tunnel. A filtering installation in the tunnel extracts the polluted air, filters out all hazardous substances and gasses and blows the clean air back into the tunnel.
The method was computed in cooperation with Oranjewoud and TNO. The results are most convincing. The HD Clean Tunnel system is realistic, feasible and affordable and offers a real solution to the pollution problem.
- The traffic flow pushes the contaminated air towards the cleaning systems near the tunnel exit.
- The heavy polluted air near the road surface is caught and filtered.
- The clean air is pumped back into the tunnel from below the road forming an air curtain that prevents polluted air from escaping the tunnel.
- Near the exit, air from one tunnel tube is blown into the other.
- This process is performed at both ends of the tunnel, keeping the air in the tunnel.
The heat-recovery system gives the system a short return on investment. The system is paid for within five years.
- Improving the quality of life and increasing the living density in a city at the same time.
- Preventing and avoiding building freezes and accelerating road network extensions and development options.
- Major CO2 level reduction and minimal emission at tunnel entrances.
- Improved access to the city and melting of city districts together: ring roads don’t form a barrier anymore.
- Revenues thanks to construction options up to the very edge of the covered road or even on top of the tunnel roof of the ring road.
- The tunnel can be funded with the proceeds of the freed building ground.
- The ventilation system purchase and maintenance costs can be funded by the energy-recovery system.
- Use of proven innovative technology.
The HD Clean Tunnel system is the only combined air-cleaning and energy-recovery system for tunnels and road-covering structure.
Hamburg’s plan to hide its highway underground
When the A7 highway was first built in Hamburg, Germany, it sliced the city in half. Now a few divided neighborhoods are starting to be stitched back together, as the city begins construction on three new parks that will fully cover parts of the autobahn.
Park 101 is a visionary urban design solution to cap the 101 FWY in Downtown Los Angeles – reconnecting the city’s historic core, north of the freeway, with the civic, cultural, and financial cores of modern Los Angeles to the south.