0:00:03 > 0:00:07# There are lots of things all around us
0:00:07 > 0:00:10# Exciting things that surround us
0:00:10 > 0:00:13- CHILDREN:- # But how does it work? - Do you know?
0:00:13 > 0:00:17- # How is it made? - Do you know?
0:00:17 > 0:00:20# Things that go up Things that go down
0:00:20 > 0:00:23# Things that go pop Things that go round
0:00:23 > 0:00:27# With special cameras to show you inside
0:00:27 > 0:00:30# It's going to be a big surprise
0:00:30 > 0:00:34- # But how does it work? - Do you know?
0:00:34 > 0:00:37- # How is it made? - Do you know?
0:00:37 > 0:00:40- # Do you know? - Let's find out! #
0:00:41 > 0:00:45Hello, I'm Maddie. Today I'm going to meet my friend Lauren.
0:00:45 > 0:00:47We're travelling on a bus.
0:00:47 > 0:00:50There are lots of people out and about.
0:00:50 > 0:00:52Some are walking their dogs.
0:00:52 > 0:00:56Other people are travelling in cars, on bicycles and, of course, buses.
0:00:56 > 0:01:01- Hi!- Hi. - Lauren, do you like to use buses?
0:01:01 > 0:01:03I love using buses. I use them a lot.
0:01:03 > 0:01:06And talking of which, there's a bus now!
0:01:06 > 0:01:07Hello!
0:01:07 > 0:01:12Have you noticed a special part of the bus that helps people to get on
0:01:12 > 0:01:16if they're using a wheelchair, or if they can't step up too high?
0:01:20 > 0:01:23Can you see that the bus is crouching down?
0:01:23 > 0:01:27ALARM WAILS And listen for that sound.
0:01:27 > 0:01:29The alarm tells us that
0:01:29 > 0:01:33something special is about to happen...and look.
0:01:33 > 0:01:36What's that coming out the side of the bus?
0:01:36 > 0:01:38This is a bus ramp
0:01:38 > 0:01:42and it means that Lauren can get on the bus really easily.
0:01:49 > 0:01:53But do you know how a bus ramp works?
0:01:53 > 0:01:54Let's find out.
0:02:01 > 0:02:04I've come to this factory, where they make bus ramps.
0:02:04 > 0:02:08Here, they make almost 2,000 bus ramps every year,
0:02:08 > 0:02:10for buses all over the world.
0:02:10 > 0:02:14Here's what the ramp looks like before it goes into a bus.
0:02:14 > 0:02:16Let's take a closer look.
0:02:17 > 0:02:22Underneath the bus, next to the wheels, are airbags called bellows.
0:02:22 > 0:02:26They're full of air and keep the bus level.
0:02:26 > 0:02:30When the driver presses a button inside the bus,
0:02:30 > 0:02:33an electric signal goes to the bellows to tell them
0:02:33 > 0:02:35to let some air out.
0:02:35 > 0:02:40As the air comes out, the bus gets lower on one side.
0:02:40 > 0:02:43It's a bit like letting the air out of a rubber ring.
0:02:43 > 0:02:46When the bus is level with the pavement,
0:02:46 > 0:02:50the driver presses another button to make the ramp come out.
0:02:50 > 0:02:53Under the doors, there's a hidden box.
0:02:53 > 0:02:57Inside the box is a bar fixed to the ramp.
0:02:57 > 0:03:00When the driver presses the button,
0:03:00 > 0:03:03the bar moves forward and pushes the ramp out.
0:03:03 > 0:03:08When the ramp rests on the pavement, it's ready to be used.
0:03:09 > 0:03:11And then, the ramp goes away,
0:03:11 > 0:03:14the bellows fill back up and the bus drives off.
0:03:14 > 0:03:17HONK! HONK!
0:03:17 > 0:03:21The bus has been brought here so we can get a good look underneath it.
0:03:25 > 0:03:29You should never go or play under a vehicle,
0:03:29 > 0:03:31but we've got permission to be here,
0:03:31 > 0:03:34so we can put my special camera under the bus
0:03:34 > 0:03:36to get a closer look at the bellows.
0:03:36 > 0:03:39I can see what's going on in the special camera
0:03:39 > 0:03:42by looking at the screen on my phone.
0:03:43 > 0:03:45Over to you, driver!
0:03:48 > 0:03:53Watch the bellows here get squished as the air comes out.
0:03:54 > 0:03:57Can you see a big black shape coming down?
0:03:57 > 0:04:00That's the bus lowering, and it's squishing the bellows.
0:04:00 > 0:04:02Let's see it again.
0:04:02 > 0:04:06AIR HISSES Whoa! Listen to the hiss!
0:04:06 > 0:04:09That's the sound of the air coming out of the bellows.
0:04:09 > 0:04:11It sounds like a snake!
0:04:15 > 0:04:20And now the bus has been lowered, the ramp is ready to come out.
0:04:20 > 0:04:21How clever is that?
0:04:21 > 0:04:24And when the person is finished using the ramp,
0:04:24 > 0:04:28the driver presses a button and it goes back to how it started -
0:04:28 > 0:04:33the ramp goes in and the bus is lifted back up by the bellows.
0:04:33 > 0:04:37Just think, that bus weighs about 12 tonnes.
0:04:37 > 0:04:39That's about the same as four elephants.
0:04:39 > 0:04:41ELEPHANTS TRUMPET
0:04:41 > 0:04:45The bellows have to be pretty strong to lift all of that!
0:04:47 > 0:04:51I loved seeing how the bus was lowered and the ramp worked.
0:04:51 > 0:04:53What was your favourite bit?
0:04:57 > 0:05:01Do you remember what you call the airbags underneath the bus
0:05:01 > 0:05:02which make it go up and down?
0:05:02 > 0:05:06That's right, they're called bellows.
0:05:06 > 0:05:10Did you hear the sound the bellows made as the air came out?
0:05:10 > 0:05:13AIR HISSES
0:05:13 > 0:05:15It made a hiss, like a snake.
0:05:15 > 0:05:18And did you see the way the ramp came out
0:05:18 > 0:05:21from a hidden box under the doors?
0:05:28 > 0:05:32So, the next time you see someone using a bus ramp,
0:05:32 > 0:05:34you'll know just how it works.
0:05:37 > 0:05:41Look around. What can you see that all the buses and cars
0:05:41 > 0:05:44are using to get around?
0:05:44 > 0:05:47That's right, it's a road.
0:05:49 > 0:05:50Roads are everywhere.
0:05:50 > 0:05:54There's probably a road by your house or flat,
0:05:54 > 0:05:58and if you go in a car or a bus, you'll go on a road.
0:05:58 > 0:06:01You might use a road to go to the shops, or to school,
0:06:01 > 0:06:03or maybe your friend's house.
0:06:03 > 0:06:07But do you know how a road is made?
0:06:07 > 0:06:08Let's find out!
0:06:14 > 0:06:19The workers here are building a new road called a motorway.
0:06:19 > 0:06:21Motorways are really big roads,
0:06:21 > 0:06:24and lots of cars and lorries travel on them.
0:06:24 > 0:06:27Have you been on a motorway?
0:06:27 > 0:06:29You should never play on a building site,
0:06:29 > 0:06:32but we've been given special permission
0:06:32 > 0:06:33to see how a road is made.
0:06:35 > 0:06:37First, a big digger arrives.
0:06:37 > 0:06:39It's called an excavator.
0:06:39 > 0:06:42And it works to dig up the soft ground
0:06:42 > 0:06:44ready for the road to be laid.
0:06:47 > 0:06:50Just look how much soil they're digging up!
0:06:51 > 0:06:54And can you hear it creaking as it scoops up the dirt,
0:06:54 > 0:06:56lifts it high in the air
0:06:56 > 0:06:59and then dumps it in the back of the bulldozer?
0:07:02 > 0:07:04After a lot of digging,
0:07:04 > 0:07:08the workers are ready to start building the road.
0:07:08 > 0:07:12First, a big truck arrives and delivers gravel.
0:07:16 > 0:07:19Now, that is a lot of gravel!
0:07:19 > 0:07:23I love the way the truck tips it all the way up in the air.
0:07:25 > 0:07:27I've got some gravel here.
0:07:27 > 0:07:29It's made of lots of little stones.
0:07:29 > 0:07:32The workers need to spread it all over the area
0:07:32 > 0:07:35where the road is going to be made.
0:07:35 > 0:07:37Do you know how they're going to do it?
0:07:39 > 0:07:42They use a bulldozer to spread out the gravel
0:07:42 > 0:07:44and make it nice and flat.
0:07:47 > 0:07:49The bulldozer is big, isn't it?
0:07:49 > 0:07:52Can you see this big metal flat piece at the front?
0:07:52 > 0:07:56Well, that's called the blade, and it's pushing the gravel around,
0:07:56 > 0:08:01creating a large flat area, ready for the road-building to start.
0:08:01 > 0:08:03It's definitely noisy!
0:08:07 > 0:08:09Now the gravel has been laid out,
0:08:09 > 0:08:13this big machine, called a roller, is going over it.
0:08:13 > 0:08:18Listen to the sound the roller makes as it rumbles and rattles along.
0:08:18 > 0:08:22ROLLER RUMBLES AND RATTLES
0:08:22 > 0:08:26It's so powerful that it's making the ground shake!
0:08:27 > 0:08:31The roller is pressing the gravel down and squishing it all together
0:08:31 > 0:08:33so that it becomes hard.
0:08:33 > 0:08:36And this becomes the base layer of the road.
0:08:36 > 0:08:40It's called the formation, and then when that's done,
0:08:40 > 0:08:43the workers lay a second layer of gravel,
0:08:43 > 0:08:46and that's called the sublayer.
0:08:46 > 0:08:49The sublayer is made from smaller pieces of gravel,
0:08:49 > 0:08:52and it's spread out over the bigger gravel layer
0:08:52 > 0:08:54and then pressed with the roller again.
0:08:54 > 0:08:57The more the layers are pressed together,
0:08:57 > 0:08:59the stronger the road will be.
0:08:59 > 0:09:04And can you see that there are still little gaps between the gravel?
0:09:04 > 0:09:07This means that rainwater will be able to drain away
0:09:07 > 0:09:11so we don't end up with giant puddles on the motorway.
0:09:11 > 0:09:15The next layer of the road is made of something called asphalt,
0:09:15 > 0:09:19and the road workers lay it using this machine.
0:09:19 > 0:09:21It's called a paver.
0:09:24 > 0:09:28This is the front of the paver, where the asphalt is loaded.
0:09:28 > 0:09:33Asphalt is made from bits of crushed rocks, sand and a black,
0:09:33 > 0:09:35oily liquid called bitumen.
0:09:35 > 0:09:37Bitumen is made from oil,
0:09:37 > 0:09:41and it's what sticks the rocks and sand together.
0:09:41 > 0:09:43It's also what makes the roads strong,
0:09:43 > 0:09:46gives them their black colour.
0:09:49 > 0:09:54This big lorry is loading the asphalt into the front of the paver.
0:09:54 > 0:09:56Then it comes out of the back.
0:09:56 > 0:09:59Can you see the steam coming off the asphalt?
0:09:59 > 0:10:03That's because it's been heated up to make it super, super hot
0:10:03 > 0:10:07so that they can pour it out of the paver and spread it around.
0:10:13 > 0:10:18Now the asphalt has been spread out, it needs to be flattened down.
0:10:18 > 0:10:20Can you guess what machine does that?
0:10:22 > 0:10:24Yes, it's the roller.
0:10:24 > 0:10:27But this roller is special,
0:10:27 > 0:10:30because the wheel is sprayed with water
0:10:30 > 0:10:33to stop the asphalt sticking to it.
0:10:33 > 0:10:37Look at the steam as the water from the roller touches the asphalt.
0:10:37 > 0:10:40That's because it's still really hot.
0:10:40 > 0:10:43To show you just how hot the asphalt is,
0:10:43 > 0:10:46I've got a special camera with me.
0:10:46 > 0:10:48This is a thermal camera,
0:10:48 > 0:10:52and it shows us how hot or cold things are using colour.
0:10:52 > 0:10:56So anything that's cold will show up as blue or purple,
0:10:56 > 0:11:01and anything that's warm or hot will show up as red or even white.
0:11:01 > 0:11:04So let's see what colour the asphalt is.
0:11:06 > 0:11:10Wow, OK. So if I point the thermal camera at people,
0:11:10 > 0:11:13you can see that they're slightly blue or purple,
0:11:13 > 0:11:17and that's because it's a chilly day. They're quite cold.
0:11:17 > 0:11:20But if I point the thermal camera at the asphalt,
0:11:20 > 0:11:22it looks golden.
0:11:22 > 0:11:25It's showing up as white and yellow.
0:11:25 > 0:11:29And that's because it's really, really hot.
0:11:31 > 0:11:33That's really interesting.
0:11:33 > 0:11:37So the roller, on the thermal imaging camera,
0:11:37 > 0:11:41is leaving darker streaks in the white hot asphalt,
0:11:41 > 0:11:44and that's because the water on the wheels is cooling it down
0:11:44 > 0:11:46ever so slightly.
0:11:48 > 0:11:53So to build a road, first the ground is dug up by an excavator.
0:11:53 > 0:11:58Next, the bulldozer lays the gravel and it's rolled by a roller,
0:11:58 > 0:12:03and then finally, the asphalt is laid by a paver.
0:12:03 > 0:12:07It's looking good, isn't it? But it's not quite finished yet.
0:12:07 > 0:12:12It has to be left to dry properly before anyone can use it.
0:12:12 > 0:12:15After a few more layers of asphalt and it's been left to cool down
0:12:15 > 0:12:20and go hard, we have a finished road!
0:12:21 > 0:12:25And now it's ready for cars and lorries to drive on.
0:12:27 > 0:12:32What was your favourite bit about seeing how a road was made?
0:12:32 > 0:12:34Do you remember the name of the machine
0:12:34 > 0:12:38that dug up the earth before the road was laid?
0:12:38 > 0:12:41That's right, it's called an excavator.
0:12:43 > 0:12:46Did you hear the sound the roller made when it squished
0:12:46 > 0:12:49all the road layers together?
0:12:49 > 0:12:50ROLLER RATTLES AND RUMBLES
0:12:50 > 0:12:53And did you see how hot the asphalt was
0:12:53 > 0:12:56when I used my special thermal camera?
0:13:03 > 0:13:07So the next time you travel on a road, you'll know how it's made,
0:13:07 > 0:13:10and you can think about all of the layers underneath.
0:13:10 > 0:13:12And when you see or travel on a bus,
0:13:12 > 0:13:14you now know how it lowers
0:13:14 > 0:13:18and how the ramp goes in and out to let people on and off easily.
0:13:18 > 0:13:20Right, that's my bus, so I've got to go.
0:13:20 > 0:13:22I'll see you next time!
0:13:25 > 0:13:28# There are lots of things all around us
0:13:28 > 0:13:32# Exciting things that surround us
0:13:32 > 0:13:35- # But how does it work? - Do you know?
0:13:35 > 0:13:38- # How is it made? - Do you know?
0:13:38 > 0:13:42- # Do you know? - Let's find out! #