Driving too slow on the highway can be as dangerous (if not more dangerous) than driving too fast.

When most of the traffic does the speed limit it goes without saying that you need to stay close to that speed too in order to be safe — without stepping out of your comfort zone, obviously.

Entering the highway is probably the most critical maneuver because of the big difference in speed between vehicles that are already on the highway and the ones trying to enter it. That’s exactly what acceleration lanes are for, to allow cars to pick up speed and then safely merge onto the highway.

Also watch: Who’s To Blame? Dashcam Captures Totally Avoidable Crash On Illinois Highway

Things are pretty straightforward and there shouldn’t be any problems, at least in theory. However, as we know all too well, in real life there are many drivers who don’t have a clue how to merge onto the highway and how to use acceleration lanes. The following video is a good example as it shows how dangerous it is not to enter the highway correctly.

The dashcam footage shows a previous-generation Toyota Corolla driving on an entrance ramp and suddenly braking just before the acceleration ramp. The cammer following from behind started honking the horn but that did help — quite the contrary, the Corolla driver, who apparently was an elderly  lady, started moving even more erratically.

You can see the Toyota waiving from one side to the other of the acceleration lane and almost braking to a halt. The driver clearly found it very difficult to merge as at one point she was almost hit by a semi going much faster in the neighboring lane. Fortunately, nothing bad happened in the end but next time the Toyota Corolla driver might not be that lucky.