The Kaimai Railway Tunnel runs for nearly nine kilometres under the range, making it the longest tunnel in New Zealand. Construction of the tunnel started from both sides of the range in 1969: the headings met in 1976 and the tunnel opened on 12 September 1978. The Kaimai Range and this tunnel led to a Silver Fern railcar service between Auckland and Tauranga being named the Kaimai Express.