Secrets of The Motorway - M25 Part 3

Summary

This video details the journey of the final episode of 'Secrets of the Motorway' series, which explores interesting facts and history about each junction along the M25 motorway in England. It starts at Junction 21, giving background on the missing slip roads, and continues clockwise, covering things like the old Radlett Aerodrome, the failed London Ringways project explaining the odd road layouts, tunnels like the longest Homesdale Tunnel, the heritage railway line near Epping, the origins of the Brook Street Interchange, and finally ending at the Mardyke Interchange, the last junction on the M25.

Takeaways

• 😀 This is the last episode of a series exploring the secrets of UK motorways that started in July 2022
• 🚗 The M25 passes through the former site of Radlett Aerodrome, an airfield from 1929 that had a grass runway
• 🚥 Junction 23 of the M25 has lots of traffic lights, making it slow to get around the junction
• 🚧 Between junctions 19-23, the M25 was pieced together from failed London ringway projects originally not meant to connect
• 🚇 An underground central line tunnel crosses under the M25 near junction 27 in Essex
• 🌉 The longest M25 tunnel is the Huntsdale tunnel in Waltham Cross, built with the cut and cover method
• 🎡 Old McDonald's Farm next to junctions 27-28 is a landmark that almost wasn't there based on old motorway plans
• ⛰ The junction 28 Brook Street Interchange was built over the River Mardyke, necessitating dedicated slip road bridges
• 🛣 Before the M25, the A127 crossed straight through junction 29, remnants of which can still be seen today
• 😊 The host John thanks viewers for their support over 80 episodes documenting UK motorways

Q & A

What is the name and topic of the video series?

The name of the video series is 'Secrets of the Motorway'. It explores different motorways in England, Scotland, and Wales.

Why are there missing slip roads at Junction 21 of the M25?

The missing slip roads likely weren't built because they wouldn't have fit at the existing Junction 6 of the M1 which was constructed before the M25. Installing them would have caused issues.

What was on the site where the M25 now passes between Junctions 21 and 22?

The site was previously Radlett Aerodrome, an airfield that opened in 1929 and was home to aircraft manufacturer Handley Page. The M25 passes between where the main runway and some buildings were located.

Why do the M25 carriageways split at Junction 23?

That section was meant to be part of the failed London Ringways project as Ringway 3 and Ringway 4. When the project was cancelled, existing sections were joined, causing the odd layout.

What is inside the large bridge near Junction 25 of the M25?

Inside the bridge is the New River, an artificial waterway built in 1613 that carries drinking water into London. The bridge was built so the river wouldn't be disrupted.

Where is the longest tunnel on the M25 located?

The longest M25 tunnel is the Huntsdale Tunnel in Watford Cross, built using the cut and cover method in the 1980s.

How does the Central line relate to Junction 27 of the M25?

The Central line railway runs underneath the M25 near Junction 27. Trains used to run as far as Ongar station until it closed in 1994.

What could have been at the Old McDonald's Farm site near Junction 28?

Ringway 4 was planned to connect with Ringway 3 at that site via an interchange. The farm may not have existed if those plans went ahead.

How did construction of the M25 impact the A127 at Junction 29?

The A127 had to be shifted over to make way for the M25 and junction. Remains of the old A127 carriageway can still be seen.

Why do the southern slip roads at Junction 30 have their own bridges?

They cross over the Mardyke River, so separate bridges were built. This also allows emergency vehicle access between carriageways.

Outlines

00:00

😀 Introducing the final episode of the motorway series

The host John introduces the final episode of the motorway series that began in July 2022. They have now visited every motorway in England, Scotland and Wales. Today they continue the M25 starting at Junction 21 which connects to the M1.

05:01

😀 M25 history and geography from J21 to J23

This section explains details about the history and geography of the M25 from Junction 21 to 23. It talks about the missing slip roads at J21 due to pre-existing infrastructure. It also covers the history of Radlett Aerodrome that existed before the motorway was built, and how you can still see traces of the old runway today.

10:28

😀 Musical interlude

A brief musical interlude with no speech.

Keywords

💡Motorway

The video is about exploring secrets and facts about motorways in the UK. 'Motorway' refers to limited-access high speed roads that are designed for motor vehicle traffic. The narrator visits and describes interesting aspects of various motorways such as the M25, M1, etc.

💡M25

The M25 motorway encircles Greater London in the UK. It is mentioned throughout the video as the narrator explores different sections of it over multiple episodes. The M25 seems to be the main motorway focused on in the series.

💡Ringway

The 'Ringways' refer to a series of planned ring roads around London in the 1960s, which were meant to alleviate traffic in the city. Only some sections were built, which became part of the current M25 motorway. The unbuilt 'Ringway' roads explain some irregularities in parts of the M25.

💡Junction

A 'junction' refers to the intersection between two motorways or between a motorway and a major road. The video describes unique aspects of different motorway junctions on the M25 and other roads.

💡Interchange

An interchange is also an intersection between highways, where traffic can transition from one road to another. Certain complex interchanges like whirlpool or stack interchanges are discussed in the video.

💡Slip road

Slip roads are roads that allow vehicles to enter or exit a motorway. They are mentioned a few times when describing irregularities at certain junctions on the M25.

💡Carriageway

A carriageway refers to a lane or section of road designated for vehicular traffic. The narrator notes cases where old carriageways can still be seen near certain motorway junctions.

💡Infrastructure

The video looks at motorways as critical transportation infrastructure that often has to be built over or around other infrastructure like rivers, railways, runways etc. This intersection of infrastructure shapes motorway design.

💡Flyover

A flyover is a bridge built for one road to cross over another. The concept comes up when describing certain multi-level interchanges.

💡Route

The route refers to the path or course taken by a motorway from start to finish. The video explores interesting features all along the routes of motorways like the M25.

Highlights

The assistant is named Claude, created by Anthropic.

The series explores the secrets and history of every motorway in England, Scotland and Wales.

The M25 passes through the site of the former Radlett Aerodrome that operated from 1929 to 1939.

Junction 23 has many traffic lights which can cause delays.

The section between J19-J23 was not originally planned to be part of the M25.

The Homesdale tunnel in Watford Cross is the longest tunnel on the M25.

The M25 crosses over part of the London Underground Central line near Epping.

Despite being closed, Epping Underground station is still used to measure distances.

Junction 27 is a rare whirlpool interchange that allows free flowing traffic.

Slip roads at J27 are separated only by traffic cones for emergency access.

Old McDonald's Farm narrowly avoided being demolished for the M25.

Junction 28 was built before the M25 and simply adapted for the motorway.

Remains of the original A127 road can be seen near Junction 29.

The A13 flyover at Junction 30 was unused for 15 years during construction.

The series covers 80 videos documenting motorways in England, Scotland and Wales.

Transcripts

hello and welcome to Auto Shenanigans

how the devil are you have you had a

good week my name is John thank you very

much for joining me for another exciting

episode of Secrets of the

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motorway this week is the last episode

of a series that began in July 2022

after a year and a half we visited every

single Motorway in England Scotland and

Wales sorry Ireland you're going to have

to wait so for the last time let's go

and explore some Motorway and today

we'll be continuing with the M25 over

the last two episodes we've we been

making our way around the M25 from the

motorway start in Dartford and we've

made it as far as the gate Valley

viaduct in Junction 20 in Harford here

today I'm at Junction 21 which is a

Motorway to Motorway interchange between

the M25 and the M1 it's free flowing in

most directions but you'll notice it's

lacking a set of slip roads that join

with the M1 on the south side of the

junction it's not exactly been confirmed

as to why they didn't build these

missing slip roads but the most logical

explanation can be found at Junction six

of the M1 this Junction along with the

motorway was constructed long before the

M25 and if you were to install the

missing slip roads at The Interchange

they most likely wouldn't fit and if

they did fit they would cause all sorts

of problems with the existing Junction 6

on the M1 so it's most likely that they

just left them out between Junctions 21

and 22 and the motorway slices through

what was previously the site of radlet

Aerodrome an Airfield that opened in

1929 and was home to the aircraft

manufacturer Handley page initially the

Airfield had a grass Runway but as

Handley page moved into the manufacturer

of larger aircraft such as the Halifax

bomber a proper Runway was in installed

in 1939 according to this map of the

Airfield the M25 passes through between

the end of the main Runway and a set of

buildings that serve various uses today

those buildings are an industrial estate

and there's little Trace left of the

runway but you can just about make out

its outline on satellite images Junction

23 or bal's corner is where the M25 and

the a1m meet and it's fine as long as

you don't need to actually use the

junction for some reason they've

insisted on installing a million sets of

traffic lights so sometimes it can take

what seems like forever to get round on

the junction you'll find South MIM

service station the first services to be

opened on the M25 in 1987 after Junction

23 and the motorway carriageways split

leading to many people wondering why the

answer is that failed London ringways

project we touched on this in the last

episode but here are the details the

section of M25 between Junctions 19 and

Junctions 23 was never supposed to

happen the original 1960s plan suggest

the two motorways known as ringway 3 and

ringway 4 would have passed through the

area a bit like this The Space Between

The Carriage RS is where ringway 3 would

have continued along its Journey with

there most likely being a set of slip

rows connecting up to the junction 23

roundabout although I don't know if it

would have been Junction 23 with project

cancellations it didn't really work out

like that but so determined were they to

have at least one orbital motor of

London the already built sections were

hastily stitched together and Junctions

19 to 23 is the result of that it's why

Junction 19 has an odd free flowing

layout and why there space up at

Junction 23 it was never supposed to be

this way just before Junction 24 if you

take a look out to your right you might

spot a railway tunnel ventilation Shaft

or two the East Coast main line runs

underneath the motorway here VI an 1100

met long tunnel actually there are two

tunnels here side by side the East Bo

tunnel opened in 1850 whilst the West Bo

tunnel wouldn't open until over 100

years later in 1959 I assume by this

point rail traffic had increased and

more rails were laid just before

Junction 25 you'll pass under at first

glance what appears to be a fairly

ordinary bridge but if you take a closer

look it's got quite a bit of depth to it

and quite a bit of width it certainly

seems a bit unnecessary for carrying a

foot path maybe it's an old abandoned

Road Bridge turns out that no this

bridge was never really designed with a

road or a pathway in mind and instead

contained within the bridge is a river

the river known as New River is an

artificial Waterway constructed in 1613

it carries drinking water from where in

har AER along a 20 or so mile long route

into London and when the M25 came along

the motorway had to be dug into the

ground and this bridge created so as not

to upset the level course of the river

here's a question for you what's the

longest tunnel on the M25 if you said

the darford tunnel then I'm sorry that's

not correct and you clearly haven't been

paying attention to the previous

episodes if you could hand in your

Motorway membership card on the way out

that' be fantastic the longest tunnel on

the M25 would be the homesdale tunnel

found in walam cross an impressive

structure it is no having been built in

the 1980s using the cut and cover method

in the early days of Motorway planning

they allocated this stretch of land for

the motorway to be built on however when

they finally got round to actually

building the motorway they decided that

the land they had allocated was no

longer large enough to accommodate a

Motorway so the decision was made to

build the tunnel instead as somehow that

was seen as the more convenient option

the grass area I'm standing on now may

not have existed had the original plans

been carried out and the view from the

surrounding houses may have been very

different indeed just before Junction 27

and the motorway crosses over a railway

but it's not just any Railway this is

part of London Underground central line

all the way out here in Essex today the

line terminates a short distance up at

eping station however up until the

mid90s the underground trains used to

run as far as chipping oner oner station

is interesting because despite being

closed to the London Underground for for

at least 25 years it's the point at

which all official distances are

measured across the underground Network

for example eping station should have a

sign displaying 9.85 km because that's

how far it is from the starting point of

measurement whilst the sign at oner

railway station should read 0.0 km I've

oversimplified things really but the

point is this now closed to the London

Underground Station is still the basis

of a measurement system still in use

today I have no idea why they decided to

use kilometers though longer station

despite being closed to the London

Underground for all of these years

remains open and operates as a her itage

Railway although unfortunately it

doesn't quite connect up with eping

station like it used to due to a lack of

platforms and signaling and other

railway stuff for now the eping Ona

Railway can't run trains into eing

station but they do have plans to change

that in the not too distant future which

will be rather handy this is Junction 27

or The thaden Interchange it's where the

M25 and the M11 motorways meet a rare

example of a whirpool interchange The

Interchange has free flowing traffic

movements in all directions and the

design is such because it takes up a lot

less space than say a four-level stack

interchange such as the one found at

thorny between the M25 and M4 an

interesting design feature of the well

poool interchange is that in places the

slip roads run alongside one another if

you've ever driven this interchange

you'll know that they're separated by

nothing more than a row of traffic cones

whilst this seems questionable it does

allow several opportunities for the

Emergency Services to switch slip Road

should they need to just boot the cones

out the way and off you go between

Junctions 27 and 28 lies Old McDonald's

Farm it turns out it's next to the M25

for Motorway Travelers it's a bit of a

landmark that stands out with its track

ction engine in a field that said it's

lucky to exist at all looking over the

1960s ringway plans what we nearly had

instead was a Motorway to Motorway

Junction or interchange right about

where old McDonald's Farm is this would

have been the point where ringway 4

connects up with ringway 3 most likely

at a limited access free flowing

Junction although some sources suggest

that there wouldn't have been a junction

at all and that ringway 4 would have run

down to connect up with the a12 at

Junction 28 in either case it's most

probable That Old McDonald wouldn't have

had a farm Junction 28 or the Brook

Street interchange most L predates the

M25 it was built in the 1960s as part of

the brenwood bypass or the a12 and when

it came to the motorway they simply

built that over the top rearranged the

slip roads a bit and called it a day

handy hint for you there's a petrol

station just off the roundabout and

Junction that's usually a little bit

cheaper than the near service station

which in this case is thurg and that's

rubbish Junction 29 is where we find the

a127 and whilst the a127 predates the

M25 The Junction does not before the M25

the a127 just passed straight through

here but it was shunted over a bit to

make way for the motorway in the

junction because the a127 was shunted

over a bit there are some remains of the

original carriageway to be found on the

east side of the junction there's some

sort of maintenance yard in which

there's a piece of the original a127 and

on the other side of the junction will

be overgrown there are further remains

of the a127 carriageway bang and the

daylight has gone the last Junction on

the M25 is The mardike Interchange named

after the river that it's built over as

a result of the river the southern slip

row have their own bridges that run

alongside the main carriageway way the

junction is where the M25 and the A113

meet and it's interesting because the

a13 heading to the west from the

junction wasn't completed until long

after the Eastern section and the M25

this resulted in the a13 flyover Bridge

sitting in a state of disuse for around

15 years whilst they finished off

construction of the A113 to the west and

there we are then guys that's all we've

got time for this week and we're at the

end of the series I had no idea when I

started I'd be making 80 videos

documenting all the various motorways

but here we are thank you very much for

watching I hope you like the series if

you did there is a course a button

specifically for that and if you haven't

subscribed already I'm not really sure

why but please consider doing so that'll

be quicked sweet awesome enjoy the rest

of your week whatever it is you get up

to my name is John you've been watching

aut o shananigans and I'll see you guys

next time for another exciting episode

of

uh something until then take care

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bye-bye

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okay

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yeah

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w

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