loop tunnel

loop tunnel

[′lüp ‚tən·əl]
(engineering)
A tunnel which is looped or folded back on itself to gain grade in a tunnel location.
References in periodicals archive ?
Premier Denis Napthine said, "For the first time, metro rail passengers, through their mobile phone carrier, will have high-quality mobile coverage throughout the City Loop tunnels and its underground stations.
The Victorian Coalition Government has reached an agreement with Optus, Telstra and Vodafone to extend mobile coverage to the City Loop tunnels, Premier Denis Napthine and Minister for Public Transport Terry Mulder announced today.
This will ensure that Melbourne s City Loop tunnels and underground stations will be mobile phone friendly.