Ventilation System The BorderTransportationSystem uses only electric powered railroad engines and these will not produce the pollution that is normally associated with vehicle tunnels.  If the system is to allow vehicle traffic, then existing technology for tunnel ventilation will be needed.  The main problem with an all electric rail system is the comfort of the passengers, and thus there has to be a method of reducing built up pressure caused by the trains.  See Moving Vehicle Pressure below for a possible solution. Index of ... Moving Vehicle Pressure