Vehicular access to the Toronto Island Airport now involves the use of a small ferry, capable of carrying about 8 automobiles or an equivalent number of trucks, which operates across the 150 metre wide body of water known as the Western Gap. Due to significant growth in traffic to the Island Airport, consideration is being given to bridging the channel with a two lane (7.4m) road. Surveys indicate that, in order to provide adequate clearance for the majority of pleasure craft using the channel, the elevation of the road surface over the entire width of the channel must be 6.0 metres above the existing road surface. Because there are many large tanker trucks involved, the maximum permissible grade is 3.0%. For a design speed of 70 km/h, determine the minimum distance from the channel edge where it would be necessary to begin elevating the road.
Note: For this problem use tables on vertical curves (vertical curve design tables)