The proposal would create an 11.3 km tunnel through the mountain range and link up the existing roads with short extensions, cutting travel distances from 304 km one-way to only 125 km, with travel time reduced from 5.5 hours to 2 hours. Within the tunnel, buses would make use of guidance technology (side-facing wheels) to allow them to travel in a tunnel with much smaller diameter than usual, thus reducing construction costs. Speeds within the tunnel are expected to be up to 80 km/h at up to 2.5-minute frequency. The tunnel is expected to have to take at least 200,000 passengers per year to be commercially viable, and would cost around NZ$150 million. This cost is based on very little research, the ground has not had the sufficient surveying to calculate an accurate cost. The cost is likely to be much higher, seeing as the tunnel is going through 5 known fault lines.