Dont's

To start of, here is the absolute worst way to connect your Highways:

All of these have two major issues:

• Only one of the highways is actually serviced by the connections. Cars can not enter or exit the road from the other highway
• Cars have to make a right turn when entering or exiting the highway, blocking all the following traffic

Doing this will clog up your highways in no time, so just don't.

Using one-way-streets we can improve this behaviour a bit. But this will actually create traffic lights on the entrance, which is less than ideal for our situation. So in the end you really should not directly connect your roads and highways

Do's

Using highway ramps, cars can actually enter and exit the highway without blocking the other traffic too much. Now we can actually connect a second highway.

This actually looks fine already. But we are still only servicing one highway. Seems like we have to build an interchange after all. Let's go over that in the next section