Automotive Law

Caught in CNY traffic jam? 3 reasons why they happen… according to science!

(This article was first published on Jan 26th, 2017) 


If you’re reading this while balik-kampunging, congratulations! You’re (probably) stuck in a traffic jam! For most Malaysians, festivals and traffic jams are an expected occurance, and horror stories of being stuck in the balik kampung jams seem to be getting longer and longer (the jams, not the stories).

malaysia traffic jam

Image from

In fact it’s not just during festivals that Malaysians endure jams nowadays. A survey done by Ford found that Malaysians are actually spending more time in traffic in general, and one in five Malaysians said that being stuck in traffic was the worst part of their day. The other day our former intern, Klaus, also told us a story of how it took him 9 hours to get from Taiping to KL because of the combination of a long weekend and 2 accidents.

But have you ever wondered what actually causes a jam? Like how we usually think there’s an accident or a roadblock further up, but then the traffic suddenly clears up with no evidence of either! This may surprise you, but most traffic jams don’t start because of accidents. And to illustrate that, we’re gonna use some non-accident examples to illustrate.


1. If you jam brake in Taiping (Perak), you can cause a jam in Sungai Buloh (KL)

Ever heard of the Butterfly Effect? Not the movie but the actual theory which says that something really small and insignificant (like a butterfly flapping its wings), can lead to a huge event which affects many people (like a hurricane). And though not on the same scale as butterflies creating tornadoes, the theory can be applied to traffic jams.

So basically, what happens is that when your Uncle Chong decides to suddenly brake to slow down because he remembered an AES camera, the car behind him has to hit the brakes as well. But here’s the thing, the car behind will go slower than Uncle Chong in order to still keep a safe distance. So if Uncle Chong slows down to 90km/h, the car behind may go to 85km/h, the car behind him to 75km/h and eventually…. JAM.

These incidents (which can include anything that slows a person down, like speed bumps) create “waves” which are passed down to vehicles behind the one that slowed down. In fact, in Malaysia there’s one place where everyone will have to slow down (and we’re not talking about speed limits).

toll traffic jam

Unless you’re using Smart TAG, you’re definitely gonna stop.

But if that’s the case, the solution should be simple right? We should all just try to keep to the same speed then everyone can keep moving forward! But there’s just one little problem: human beings are terrible at driving. Don’t believe?

A bunch of Japanese researchers actually ran an experiment where they got cars to drive around in circles, and they found that over time, someone will  slow down, and eventually cause the cars to clump up. When they did the experiment with self-driving cars (which are programmed to travel at a constant speed), the traffic was constant – no jam.

Check out the video of the experiment below, it’s really quite funny cos it’s true:

And funny enough, speed limits tend to make the problem worse (in some countries, you can actually get fined for driving too slow). For example, Uncle Chong may think that travelling at 110km/j means he’s a superstar on the fast lane, but in actuality he should be in the middle or slow lane – fast lanes are for overtaking (technically la). So when a car travelling at 140km/h comes upon Uncle Chong’s car, he has to brake, which causes a “wave”.

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In fact, the driver may even get pissed off and do some other unsavoury things. Which leads us to our next point.


2. If you cut queue, you’re making things worse for EVERYONE

Most of us would notice that when traffic is bad, the jerk-level of certain drivers start to rise. This eventually leads to really jerk-like moves like zig zagging between lanes, going very close to the car in front, cutting queues at turnings, etc.

But it seems that not only will these actions make you go slower, it actually makes it worse for everyone as a whole! 

“The intuition is if you are more aggressive, you will get to your destination faster.

Studies have shown that if you are less aggressive, you’ll get there faster.” – Hesham Rakha, a professor of civil and environmental engineering at Virginia Tech, as quoted by WSJ

An example is how some most people who potong queue are more than happy to wait until someone gives way to them. This actually starts a chain reaction of cars creating a second line, and as more and more people try to potong, it creates a reverse funnel like effect where a 3 lane highway becomes a 1-lane for people who want to go straight.

babi driver cut queue

Image from Yes we didn’t make this.

And of course, the zig zagging causes cars to brake, and… see point 1.


3. If you drive on the road, it becomes more jammed (DUHHhh..)

one side jam

Don’t you wish you were on the non-jam lane sometimes? Image from

So in the end, the number of cars on the road will still play a role in traffic jams. It sounds like a pretty straightforward idea, but there’s actually a lot of science (especially math) behind how many cars makes for a worse jam.

We might think that the maximum capacity of a highway is calculated by the number of cars, but actually it’s calculated by the number of cars the road can accomodate per hour, along with average speed a car can travel on that road.

A lot of systems have a vulnerability point, which is like a threshold of how much a road can tahan until things start spiraling out of control. So the problem with festive travel isn’t just because cars being on the highway, but that a lot of cars are trying to enter the highway at the same time.


Will we ever see the end of traffic jams?

That is the question isn’t it? Well you can find multiple articles online with suggestions on how that can happen like:

  • Variable speed limit – the speed limit changes according to how many cars there are on the road
  • Traffic guides – Police cars that drive in a row for other cars to follow behind in an orderly fashion
  • Intersection traffic lights – to control the number of cars entering the highway

perlahan depan jam

And when it comes to Malaysia, there is actually news about how the gomen is trying to reduce jams already. But we don’t really feel it don’t we? Well, perhaps there is actually something that we Malaysians can do to help with the situation.

Every year we hear about how the police would be conducting some operations to ensure people stay safe on the roads. And this year they said have said that they may even saman traffic offenders on the spot.

And though it would be great if the police could actually enforce it all year round, but as one columnist put it, every Malaysian has a role to play in making our roads safe

As the Malay proverb puts it:

Biar lambat, asalkan selamat

So stay safe and have a safe balik kampung trip ugaiz!


This article was written by UiHans.

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