There was little traffic. / There was a little traffic. / There was heavy traffic

Question

As I understand it (from the picture), the meaning of these sentences is opposite. Right? Then, what's the difference between "a little traffic" and "heavy traffic jams"? Is it a length of bad traffic, or a speed of traffic, or something else?

There was a little traffic. (there was traffic jams, but it's not heavy traffic jams yet. Right?)

There was little traffic. (nearly no cars on the roads)

Answer 1

It's a continuum and I doubt you'll find clear dividing lines, but the progression goes like this:

• Little traffic. Very few cars on the road. You can proceed at full speed.
• A little traffic (synonym: some traffic). There are some cars on the road, and occasionally you have to slow down or get delayed at a stoplight longer than if there was no one else driving. You have to slow down a few times and might even be stop-and-go once or twice on your commute (if such a thing happens often).
• Traffic. There are a fair number of cars on the road. It might take two cycles or more to get past stoplights. There is no question of proceeding at full speed. If you don't plan for it in advance, you will be late to your destination.
• Heavy traffic. Bumper-to-bumper cars; it would be dangerous to go as fast as the speed limit. Being stop-and-go for a long stretch of time is likely. Unless you leave very early, you will be late.

These terms are all relative, both to themselves and to the situation. Someone who lives in New York City will have a very different definition of "heavy traffic" compared to someone who lives in a rural town in Kansas.