One of the most bewildering aspects of the London Underground is learning the difference between “busy,” “crowded,” and “Oh dear God, why did I get on this train?” The tube doesn’t get to Japan level crowded, where you are pushed aboard the train carriage by a underground employee with a stick, mainly due to the lack of funding for staff, but still…

Londoners will never openly complain, they will simply sigh or silently stare into the void. But you, dear tourist, need a system. So here is the unofficial, extremely scientific guide to Tube crowding.

Level 1: Busy.

If you can enter the train without touching anyone, even lightly, congratulations, this is a luxury. It means you have room to sway gently, hold a pole if needed, and breathe without inhaling someone else’s shampoo. “Busy” is as good as it gets during most hours.

Level 2: Full.

If you have to grab a pole the second you enter the carriage, you’ve entered “full.” You are now part of a delicate ecosystem of mutual support where everyone silently negotiates elbow space. Don’t move too much. Don’t shift dramatically. Don’t sneeze. Just blend in.

Level 3: Very Full.

This is when the train doors open and the crowd on the platform sees the situation but decides to attempt boarding anyway. People wedge themselves in sideways, diagonally, spiritually, you name it. During this phase, personal space is a myth. You become very close friends with strangers, sharing breath, air, warmth, and occasionally deodorant scents.

Level 4: Rush Hour Full.

This is where things get primal. The train isn’t a train anymore, it’s a human lasagne. Layers upon layers of commuters stacked in a single carriage. You cannot lift your arms. You cannot turn your head. You cannot do anything except silently question your life choices. If you can still inhale without someone’s scarf filling your lungs, consider this a win. On the plus side, you don’t need to hold on to anything, the weight of the crowd keeps you upright no matter what.

Level 5: Absolutely Not.

When the platform itself becomes so full that staff members begin managing the flow like air-traffic controllers, you are witnessing the rare but dramatic “Absolutely Not” level. Trains arrive. No one gets on. People stare at each other in shared despair. The journey may take 20 minutes or two hours, no one knows.

Londoners, of course, downplay all of this. If they’re crushed between twelve strangers, they’ll still describe it as “a bit busy.” If you’re in a situation where you fear losing a limb, a Londoner might shrug and say, “Could be worse.”

The key to surviving crowding is knowing when to attempt boarding and when to wait for the next train. As a general rule:

• If the carriage looks full, it’s already too late.
• If you can see daylight beyond the crowd, go for it.
• If the doors open and no one moves, accept your fate and prepare for compression.

Welcome to rush hour. Please keep your arms and dignity inside the vehicle at all times.