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Pylon hunt 20: Sundon Substation, 23rd September 2023

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Destination Sundon Substation via Chalton
Goals Chalton crossing
Distance 17.3 miles (total on foot)
Walk number 175

Another day of sunshine and clouds. I’d known for a while about a double crossing at Chalton, where a 132 kV line passes under not one but two 400 kV lines, all three emanating from Sundon Substation. Depending on time and energy, I had a choice of returning straight from Chalton, or walking from Chalton to Harlington, or from Chalton to Harlington via Sundon Substation. I ended up following the full route past the substation.

Chalton is half-way between Leagrave and Harlington stations on the Midland Main Line. Thus, I headed for Leagrave.

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My Thameslink class 700 keeping pace with an EMR class 360; both trains were manufactured by Siemens

From Leagrave station, the route is north out of Luton:

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Toddington Road; always glad to see lots of trees
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Brooklands Close, having just walked past a George VI pillar box …
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L4(m) DT; this is one I didn’t think I would get to photograph, as there is no pavement or footpath close to it; pylon hunt 22 to Bedford was aimed in part to get closer to this type

One advantage to walking (instead of cycling) is that you are afforded the reaction time to spot things you would otherwise miss, especially little creatures on the ground and in hedgerows.

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Honeybee
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Why did the devil’s coach horse cross the road? To get itself killed. I tried to persuade it otherwise, but it was dead set on destruction.

Back to walking …

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An unusual way to achieve 90° deviation on wood poles
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Looking south along the Midland Main Line, with an EMR class 222 express approaching
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Sundon substation in the distance
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Sundon substation is big, with four 400 kV lines and five 132 kV lines plus a 25 kV supply for the railway; we won’t see it again for a while.
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A sneaky pylon visible in the distance (Balfour Beatty L6)

Here the route changes from roads to public footpaths. I don’t look at satellite imagery beforehand (as it spoils the surprise); I envisaged this part of the walk to just be across the middle of a field but it turned out to be a lot more scenic.

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Heading west, with Chalton over to the right somewhere
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Looking south-west towards Houghton Regis
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Continuing on
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Approaching the ZA line
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Getting closer
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This pylon is outstanding in its field …

Here we turn right and head north, continuing to pass around the outside of Chalton.

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Chalton crossing is still some way off
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400 kV L2 line tower ZA422
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Tower identification plate
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Chalton crossing

At this point, the sun scurried away and hid. It knew exactly where I was heading and when to disappear!

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Balfour Beatty L6 D60 on the left (4YJ003) and (Blaw Knox) L2 D60 on the right (ZA420); the 132 kV line passes below
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Balfour Beatty L6 D
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L6 D30 in the distance
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Close-up on 4YJ003
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Line 4YJ uses triple-conductor bundles; here you can see one of the spacers
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PL16 D10 earthwire changeover tower, where the 132 kV line divides to form the diamond crossing around the 400 kV towers
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The side corners of the diamond are carried on miniature S30 towers; note the Supergrid wires above
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The crossing seen in slightly better light

Finally heading to Chalton …

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I also knew that this Balfour Beatty L6 D40EC was here, but there was no way to get a clear shot, and there wasn’t enough light
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Hmm … this public footpath is completely overgrown and impassable. Not going that way!
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Approaching Chalton directly along the road instead

Sadly, there wasn’t time to look around the village of Chalton itself. I headed straight for the substation.

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National Grid Sundon Substation; you can’t actually enter it, but there is a public footpath alongside of it
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I wasn’t expecting this …
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Alpacas seem to be popular around here

A quick diversion across the M1 …

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Vanessa atalanta (red admiral) butterfly
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Close-up
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2023 has been a bumper year for red admiral butterflies
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An elusive Comma (Polygonia c-album) keeping a low profile
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Red berries
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This is an Eve terminal tower, although the line terminates one tower along.

Having crossed back over the M1, we follow the public footpath to the substation. I was expecting some kind of industrial wasteland, but instead I got a scenic woodland trail.

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Mud, of course!
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A PL16 DT seen through the trees at a sharp bend in the footpath; this is tower PU1 which is the start of the Sundon–Aylesbury 132 kV line that we saw at the crossing
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The footpath continues past the crossing but there is technically nothing to stop you from leaving it and walking over to the substation, which is fenced off. Quite a few of the pylons are actually outside of the substation perimeter,

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Sundon substation
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Assortment of equipment
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Close-up

Walking alongside the substation, I got chance to document several tower types.

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My first ever clear look at an L2 380ST; this terminates one circuit of a line at 380 kV (in reality, 400 kV), with the basic ST only supporting L2’s lower voltage of 275 kV
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L2 D40 EWCO (earthwire changeover) where the two circuits split out for separate termination
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Balfour Beatty L6 ST (single circuit terminal)
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Another view of the ST
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An L2 SFX gantry hiding behind the bushes; this is the only one anywhere near me
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Close-up view of Stockbridge dampers, if nothing else to show that I can pull off such a photo now!
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Ground-level termination
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I heard a Merlin-engined aircraft approaching but didn’t succeed in getting a good shot of it :(

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Looks to be an Avro Lancaster

Final shot from the substation:

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This L6 ST has a “Superman” pose

I did have to double back on myself all the way to where I left the footpath, as part of the River Flit runs between the footpath and the substation and I couldn’t find anywhere else to cross it!

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Another failed attempt to get a look at the L6 D40EC

Here it got a bit stressful. The public footpaths in the Sundon area are not well signposted, and I completely lost sight of where I was meant to be going. I ended up going too far and reaching a dead end. For some reason there were construction workers up to something, and their huge muddy track through the fields was, for a distance, the route of the public footpath I wanted.

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Pylon used as a public footpath marker
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Looking up at an L7 D
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Nature’s forgiveness for failing to save that devil’s coach horse beetle earlier

Fortunately, despite getting lost, I found my way back to Harlington and a suitable train pulled in just as I arrived at the station.

Heading home …

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View from the train
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On foot
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Bench. No cat.
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Some pink flowers.