The Train and Tunnel have equal lengths d=5. When the train and the tunnel have constant speed 0.6 c relative to each other. The train's nose (at its x=0, t=0) synchronizes with the left entrance of the tunnel (at its x=0, t=0).

When the Tunnel is Stationary...
From the point of view of the (stationary) tunnel with at-rest length d = 5 , the train's length is observed to be 0.8 d = 4.

The moving train's clocks run at 80% the rate of the tunnel's clocks. (Check the reading of the moving train's nose clock against the stationary tunnel clocks .)

When the Train is Stationary...
From the point of view of the (stationary) train with at-rest length d = 5, the tunnel's length is observed to be 0.8 d = 4.

The moving tunnel's clocks run at 80% the rate of the train's clocks. (Check the reading of the moving tunnel's entrance clock against the stationary train clocks.)