It was a northbound train, leaving Alinga Street at about 6.30pm - the rush hour - and the front carriage was packed.

A rather grand lady decided that this was a communal experience and she would talk to people!

She opined about the cost of private schooling. She told us all what a marvelous thing the tram was but how the bus services for her children had been affected.

At one stage, she said to a professional gentleman next to her, "Let me tell you what happens." He muttered, "If you must", and shuffled in embarrassment.

The rest of us looked deeper into our phones. If we could have drilled into them and hidden, we would have.

Talking to strangers on the tram!

It couldn't have been worse if she'd stripped off and done a belly dance with tassels and a gemstone in her navel.

Not that this would have been easy in the packed carriage.

There is an etiquette to tram travel. Probably each city develops its own but already a code of behaviour is developing in Canberra - loud mobile phone conversations already seem to be frowned upon.

But the voluble lady hadn't learnt another rule: a tram journey is not some sort of high-society cocktail party where polite conversation with strangers is expected.

On the tube in London, the government was so concerned about tourists not understanding the etiquette that it published the rules.

Rule Number 1: "It's OK to be quiet".

The grand lady hadn't realised this on the Canberra tram. Her one way "conversation" started because she mistook polite but limited chatter, as people adjusted to the packed conditions, as a green light for conversation.

Some interaction is allowed. Maybe a restrained smile as you shuffle in to create space for late-comers who rush and squeeze in as the doors close.

After the minimal talking rule, Rule 2 is that you don't crowd the doors and do make space. This rule of politeness is already well developed in Canberra.

But a packed tram is a competitive environment.

Seats are limited. All the same, Rule 3 is that you don't rush madly for one if you are first on. That is undignified. You may have sharp elbows but you hide them.

The best operators know how to get a seat without demeaning themselves by sprinting.

It is not a race for the lifeboats so wait strategically on the platform - but with a false calmness. Be cunning. Hide your zeal to sit. Know where the doors of the incoming train will be.

In this, small women have an advantage. People don't assume they are aggressive so they get away with more. They can play the gallantry card: few macho Australian males are going to actually push a woman to the floor in order to reach the seat. Few.

Rule 4 is: backpacks off. On the tram on Friday, one studentish girl hadn't realised that. In more brutal cities, she would have been jostled. Other passengers would have nudged her backpack, discombobulating her until she got the silent but forceful message.

It's early days on the Canberra light rail system so her rather sad ignorance of etiquette was tolerated. It won't be in six months. Just a friendly warning.

This etiquette matters. Sociologists have studied how "the seating layout of public transport forces people into an intimate distance with strangers, causing social discomfort."

In plain English: we get anxious when we are pushed together intimately with those we don't know.

One American sociologist said that passengers were "familiar strangers". Commuters saw other commuters as scenery rather than as people to engage with in pleasantries.

The talkative lady may be what sociologists call a "latent conversationalist", someone who is keen to chat but feels inhibited.

A breakdown or a delay can remove this inhibition.

"Travelling for non-work situations, such as going to the same sports event wearing your team's colours, also provides the grounds for a perception of commonality between passengers that can foster greater interpersonal communication", according to Dr Jared Thomas who researched the matter at Victoria University in Wellington for his PhD.

He observed 1,703 passengers and concluded that there were ways to "facilitate conversation". "Asking simple questions such as 'do you have the time?' or offering comments about the weather may engage someone.

"Observe the other passengers' response, including their body language, and if it is positive, attempt to continue the conversation.

"Positive body language and smiling helps, but it is important to remember that people are very good at discerning whether your smile and intentions are genuine."

Or adhere to Rule 1 of Tram Etiquette: do not attempt to have a conversation with a familiar stranger. Maybe a weak smile to show an absence of hostility but that's it.

The grand lady on the northbound tram will learn. She had better. It's a brutal world on a crowded light rail vehicle.