Signal on the highway

I usually go to school by trains. But sometime I go there by my car. I use Tokyo Gaikan Highway for its convenience and to shorten time to reach my destination. Of course, when there aren't any trafic jam , I feel really refreshed. I always drive Misato IC(Interchange) to Wako IC[about 20 minutes drive].
By the way, have you ever seen any signals on the highway?? Look at the largest picture. Remarkably, there is a signal only at Bijogi Jct.(junction)
Although it's for trafic control, do you think it ironic there to be a signal on HIGHWAY!!