did a couple of measures recently. inside and outside tunnel temp difference is 7 to 8 C. If outside 30+, wah.... inside will be close to 40 or over. i wonder if it is a safety issue with the heat. the vent fans seem to take hot air from outisde and blow into tunnel and not the other way around. i wonder why? i suppose wait for some unfortunate accident, got fire and then whole tunnel gets supper heated and............then someone will take notice and do something about it.