The on-ramp is a necessary and integral part of the road system. Without it, we would just be staring at multiple, car-less lanes above or below us from the side streets with no way of accessing them. They are the arteries of the highway system and serve two main purposes.
This will mostly focus on the proper etiquette of the on-ramp, but I will touch briefly on the off-ramp.
The on-ramp serves two main purposes. The first purpose is the most obvious. It connects side streets to highways. I want to emphasize real quick the difference between side streets and highways.
Side Street: a smaller street that connects to and often ends at a main road. Thanks for that Merriam Webster. A side street for reference (in this post anyway) is around 45 MPH or less speed limit that has an on-ramp onto a highway.
Highway: another term for express way. Please note the word express. Meaning fast.
I feel I'm being too technical, but this was needed to prove the second (which should be obvious now) purpose.
The second purpose of the on-ramp is to get up to the speed of flowing traffic!!! Too many times daily do I have to follow behind someone on a loooooooonnnggggg on-ramp, only for them to be doing 20 or more MPH below the flow of traffic when it comes time to merge. It's not safe at all. It's actually how a lot of accidents occur. Not because of speed. But because of a mismatch in speeds between multiple vehicles.
So please, when merging onto a highway, put your foot on the gas and make sure to be going at minimum the posted speed limit. In most cases, faster than that (imo), given how most people go faster than the posted limit.
The off-ramp is much more simple and in my experience, not as dangerous as the on-ramp. The key to the off-ramp is again, proper speed. If you have the ability to coast to the stop light, stop sign, or whatever it is ahead of you, as long as the traffic ahead bides you the opportunity, you do so. More than likely there is traffic behind you. If you slow down from 65+ to 45- (too quickly), that is a recipe for a fender-bender.
One more thing about off-ramps. If there are multiple lanes ahead, like 2 lanes for left turn (the right of which allows to go straight as well), and 1 for straight and 1 for right turn...get in your lane early! I can't say this enough, drive with a purpose. I have gotten in my lane as early as the stripes allow me to, and too many times have I been cut-off by someone flying over from another lane with 10 yards before the intersection.
So please, don't fret to put the hammer down when merging onto a highway.
Also please, maintain as consistent speed as possible when exiting and be decisive in your lane choice.
imgs courtesy of google