Secrets of The Motorway - M25 Part 3
Summary
TLDRThis 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
- ๐ This is the last episode of a series exploring the secrets of UK motorways that started in July 2022
- ๐ The M25 passes through the former site of Radlett Aerodrome, an airfield from 1929 that had a grass runway
- ๐ฅ Junction 23 of the M25 has lots of traffic lights, making it slow to get around the junction
- ๐ง Between junctions 19-23, the M25 was pieced together from failed London ringway projects originally not meant to connect
- ๐ An underground central line tunnel crosses under the M25 near junction 27 in Essex
- ๐ The longest M25 tunnel is the Huntsdale tunnel in Waltham Cross, built with the cut and cover method
- ๐ก Old McDonald's Farm next to junctions 27-28 is a landmark that almost wasn't there based on old motorway plans
- โฐ The junction 28 Brook Street Interchange was built over the River Mardyke, necessitating dedicated slip road bridges
- ๐ฃ Before the M25, the A127 crossed straight through junction 29, remnants of which can still be seen today
- ๐ 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
๐ 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.
๐ 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.
๐ Musical interlude
A brief musical interlude with no speech.
Mindmap
Keywords
๐กMotorway
๐กM25
๐กRingway
๐กJunction
๐กInterchange
๐กSlip road
๐กCarriageway
๐กInfrastructure
๐กFlyover
๐กRoute
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
[Music]
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
[Music]
bye-bye
[Music]
okay
[Music]
[Music]
yeah
[Music]
w
[Music]
5.0 / 5 (0 votes)