HOUSTON I-45 Parkway + Tunnel

 
I-45 Parkway & Tunnel Concept - A Long Term Solution
Most Houstonians when they hear the alternative of roadway tunnels think that tunnels will not work in Houston. This is categorically wrong. In the 1950s two tunnels were installed under the Houston Ship Channel, the Washburn Tunnel and Baytown Tunnel. The Baytown Tunnel was removed in 1997 to allow deepening of the ship channel but the Washburn Tunnel is still in use. Wikipedia has a very good summary of the Washburn Tunnel.
Picture Source: citynoise.org
As the Harris County web page indicates "Flooding is practically impossible. Pumps located under the road surface drain the water back into the ship channel. As to this date, the Tunnel has never been flooded." The fact is that tunnels are very common alternatives for building roadways in urban areas and tunnels are engineered not to flood.

Following are some examples of roadway tunnels with web links:

A unique roadway tunnels is the Laerdal Tunnel located in Norway. Note that in northern European countries roadway tunnels throughout time have been used for dual purpose, for transportation and for emergency evacuation in case of national disaster or war.
Leardal Tunnel, Norway
International tunnel experts and local geotechnical engineers have been consulted about the potential to build roadway tunnels in Houston. Categorically these experts indicate that it is possible to build tunnels in the soil conditions found in Houston. However, tunnel experts recommend to conduct a tunnel feasibility study to determine particular characteristics regarding the method and related costs.