Not many people get to park their car here – bang in the middle of Heathrow airport, on the taxiway just a stretch of grass away from where a line of passenger planes is coming in to land.

It's close enough to see the shimmering air and smoke as nose tyres hit the tarmac. "An A380 will put down as much rubber as a car's entire tyre," Jack Quantick-Thorne says. He knows – part of his job is to ensure the runway team scrapes it off and patches things up overnight. And it is all recycled, he adds.

The airfield operations officer is not in the limelight much, but is one of a host of unsung workers keeping transport moving. And some jobs far from the public eye turn out to be not only essential, but surprisingly challenging.

Jack Quantick-Thorne, airfield operations officer, Heathrow

Passengers might only catch a glimpse of Quantick-Thorne from a window seat on landing, if he grabs the paddles to marshal a plane into the exact designated spot at the stand. "People just think you're that person with the table tennis bats," he grimaces slightly, as the Guardian requests a demonstration. "That's like 5% of my job."

In fact, most planes are now brought to the stand via laser-guided electronic displays. But human marshalling remains a crucial backup. Brandishing the paddles, Quantick-Thorne beckons in a taxiing British Airways arrival, the pilot peering down from the cockpit and steering 50 tonnes of plane straight towards him. The nosewheel travels bang on the guideline, stopping exactly in position for the airbridge to swing in and allow passengers to disembark.

Nerve-racking? "No. When you've got a really big plane, an A380, you need a second marshal right by the wheel to check it's stopped in the right place," he says.

Back in the car, the job continues: "I'm patrolling, I'm looking around, scanning everything – is the refueller doing his job properly, has the aircraft got chocks under its wheels?"

That includes monitoring the road system under Heathrow's airfields, recognising every vehicle and checking any infringement: drivers here can also clock up points on their licence, if he spots them.

Officers also need to look out for wildlife – particularly birds, a serious danger for jet planes (and vice versa). How does he deal with them? "We've got methods of dispersal," says the airfield operations officer.

These, marvellously, turn out to be speakers on the roof of the van, which play a range of bird sounds: "If I saw a flock of starlings, if I played a starling noise, the starling would think, 'Oh, maybe there's a predator nearby,' and they fly off."

And, he demonstrates, "I've got common gull. Black-headed gull. I've got a falcon".

Are there falcons? "No," he explains patiently. "So you think about it from a bird's point of view. If there's a pigeon over there, best play a falcon so it will fly off."

If he now knows birds, it's the planes that drew him here. He was previously at Nats, the air traffic control centre in Swanwick, managing the planes, but never up close. There is more to it than the paddles – but, he confesses, he takes every opportunity to use them, and records each plane that he has marshalled, including every aircraft in BA's short-haul fleet.

Being a pilot is the dream, he admits, but the prohibitive training costs – £100,000 or more – put it out of reach. For an enthusiast, he reckons the job is the next best thing. Last year he had to tow the Concorde that still stands at the edge of the airfield across for an exhibition: "It was the first time one had moved in years – incredible to see in the rear-view mirror."

Chris Thackaberry, network traffic controller, Transport for London

The day starts in Victoria Station House overlooking the bus terminus, a grand old building that looks considerably less so inside, where Chris's desk is surrounded by hundreds of cardboard diversion signs.

About 500 of the capital's 19,000 bus stops are on his patch in Westminster – home to some of Britain's most congested streets, where dozens of bus routes cross. Roadworks are the bane of the bus and Thackaberry's job is to keep them moving – armed with a van, pliers and zip ties.

Sometimes he can plan for roadworks months ahead. But other days are less predictable, when life suddenly blocks a route: "It could be a broken-down vehicle or a burst water main, but I've had windows falling out of buildings, I've had a collapsed horse on a bridge. I had an upside down Lamborghini in Piccadilly … I don't know if it was sticking to the 20mph limit."

His incident response van contains an orderly standing desk area and even a printer to rustle up more signs if needed, as well as spill dry sacks, ready to suck up any diesel or oil leaked over the road.

It also has two cylinders affixed to the wall containing "spit kits" – swabs to pick up any saliva aimed at staff, with clear bags to seal, ready to take the evidence to the police. "It's just part and parcel of when you're working in London, for anyone in uniform."

In a sweltering Trafalgar Square, as he hunts in the midst of four lanes of traffic to hitch his cardboard signs to any available piece of spare street furniture, the complexity of the puzzle becomes clearer.

"There's so many routes go through here, we're fighting with ourselves for space."

Sarah, railway signaller, York

Gone are most of the signal boxes of old: these days, Britain's railway is mostly controlled from one of 12 remote centres. From a windowless room in York, trains right down the East Coast mainline are guided on their way.

"In the old days, it was lever pulling," says Sarah. "Now it's a click of the mouse instead. Like a computer game scenario, but it's real track, real trains, real people. We have to manually click, signal to signal, for every train that comes through our patch."

Signallers have five screens at eye level showing the railway, and five above with timetables and traffic management information.

"When you first start the job, it feels so far removed. There's no windows, it's like a black hole in the middle of the building, but you are signalling trains from York all the way into King's Cross. I remember thinking: 'How many hundreds of people are on that train we're signalling?'"

Anything from a circuit failure to a trespasser to a sick passenger on a train can hold up the lines. "Our job initially in any incident is to make the area safe – that's first and foremost. And then we look for a workaround, to keep trains moving. The days when there are serious incidents are few and far between. But every day there's something."

Jamie *, public service vehicle engineer, Manchester

At Jamie's bus depot, servicing the Bee Network, the first shift starts at 5am and the last ends at 1am, but engineers might stay through the night with a breakdown.

"In the daytime it's routine: vehicles are inspected by law on a monthly basis," he says. "But engineers have bus driving licences too, if a bus was to break down, often we'd take another one out to the driver to keep the service running."

With city buses that stop and start frequently, there is typically more treatment and maintenance. And newer vehicles don't necessarily mean less work, he says: "They bring a lot of new issues and we're constantly learning, going back to college on courses to learn the tech.

"Electric buses haven't made the job easier – but they and the new diesel engines are clean. Working back in the day, it was a hell of a lot dirtier, especially in depots indoors or undercover," says the vehicle engineer.

He will check each bus's brakes, emissions tests and inspect the nuts and bolts everywhere from the underside to the driver's cab. "We see a lot in the press about the conditions in the cab, but we're cleaning those buses: it's like a greenhouse, and the heat from the engines also comes into our workshop.

"Even the drivers don't understand what engineers do – I always say we are the forgotten people. But without us, no wheel would turn."

Frankie *, baggage handler, Gatwick

The thing people don't understand, explains Frankie, is that the placement of bags in the hold is not random. "It's all done on weight distribution. You have to put baggage where you're told – it is a very specific job, you do not deviate."

At many airports, larger aircraft such as long-haul planes are loaded with bags already in large crates, lifted into position by machine. But short-haul flights at Gatwick are loaded manually. "An average bag is about 20kg and the average load is 90 bags off, 90 on, for three or four people. If you do eight turns a day, that's nearly 30 tonnes your team is lifting. You get fitter – it's like going to the gym, you end up lifting heavier and heavier bags."

Passengers who fear for their luggage often make the job harder: "The worst thing is shrink-wrapped bags. It's slippery, harder to hold on to, and less grip for the belt to pull up. And those straps around bags, they can get jammed in the belts and break them.

"People don't realise how damaging it can be – and pointless. If you're on a flight where customs do spot checks, they go for the bags that are wrapped. And there is so much CCTV and security. If I get caught opening a bag, I'd lose my job – why would I risk that?"

There are, says Frankie, more women doing the job now: "It's getting more female-friendly. A lot of people choose this type of job to get into aviation: they want to be pilots or crew eventually, and just want to be around planes any way they can."

* Names have been changed