A new model we're going to build has an elevated 4-lane freeway that has an interchange with a conventional highway below it. The highway is made up of 2-lane one-way couplets 1 block apart. So there are 4 signals controlling the interchange, one at each ramp access point in a tight diamond configuration. Because the 4 segments of road between each signal are all one way, traffic is allowed to turn left at the signal after coming to a stop.
