30.09.18 Penrhos Garnedd (SH 560 702)
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| Ysbyty Gwynedd perched at the top of Penrhos Garnedd |
Penrhos Garnedd has been
transformed from its moorland topped
cairn in to a suburb of Bangor which comprises a number of housing estates
and is dominated by Ysbyty Gwynedd; the main hospital for this part of
Wales. However, it still has a superb
view of the higher Eryri peaks, but because of the plethora of houses and the
hospital, this view has to be hunted out.
I’d visited this hill twice
before, the first time in October 2009 when on a bagging trip around Ynys Môn
(Anglesey) with this hill tagged on at the end of the day before heading back
to my mother’s house in Nantlle, and the second when my mother was in hospital
in Ysbyty Gwynedd. On the first occasion
I roamed around the hospital grounds, visiting the helipad and the public
footpath which leads adjacent to where LIDAR places the summit of this
hill. On each prior visit I hadn’t
investigated the near housing estate which comprises a street named Bryn Ogwen
which LIDAR indicates is a candidate for summit position.
The initial LIDAR
analysis of this hill was conducted by Aled Williams who went to each potential
summit position when visiting the hospital, I now had the opportunity to do
likewise after receiving a phone call from my brother who had fallen and broken
his hip and was now in Ysbyty Gwynedd.
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| LIDAR image of Penrhos Garnedd |
Prior to visiting my
brother I had spent a number of hours analysing LIDAR to accustom myself with
the lay of land, as Aled had asked if I could Trimble these potential summit
positions and I also wanted to compare the DTM model to the DSM model and build
the contours and examine the streets and compare their highest point to the
land overlooking the high Eryri peaks at the back of the hospital.
Having packed spare
clothes, books and other necessary items for my brother I headed toward Bangor
in the late afternoon and parked in the hospital grounds. It is only a couple of minutes’ walk from the
hospital to the crossroads between Ffordd Penrhos and Coed y Maes which is the
high point of the road as it passes over and through Penrhos Garnedd, with the
conurbation taking on the name of its founding hill. The meeting of these roads is another
potential high point for this hill, although LIDAR suggests otherwise and if
time permitted I wanted to take a data set from here after visiting and
surveying the other two potential summit positions.
Turning right at the
crossroads led me toward Bryn Ogwen, which is a street and not the name of the
hill as listed in the Tumps. This street
is narrow and has a number of high hedges dotted along it and the ten figure
grid reference produced by LIDAR led me toward what looked to me as the highest
hedge in the street, which wasn’t ideal for satellite reception.
As there were a number
of chopped logs at the front of one of the houses I used one to position my
rucksack on top to give it a semblance of elevation above its immediate surrounds
and then began a long wait until the 0.1m accuracy level was attained before
data should be logged. During this wait
a woman came out of another house to take in her washing as it had begun to
spit with rain, I asked if she minded me taking a second data set from the top
of her gate which was a few metres away from the Trimble’s current position and
was more open compared to its position on the log and my rucksack.
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| The first Trimble data set at Bryn Ogwen |
Once the first data set
was complete I re-positioned the equipment on top of the gate post, measured
the offset between its internal antenna and the ground at its base and waited
for the allotted data to be gathered and stored. During this a number of children were massing
asking all sorts of questions, their first being ‘are you bird watching?’,
which made me smile.
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| The second Trimble data set at Bryn Ogwen |
Happy that I had taken
two data sets from Bryn Ogwen I walked the short distance down to the near
public footpath which leads south-eastward toward the back of the hospital and
then down toward the A 4087.
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| The public footpath leading to the summit of Penrhos Garnedd |
As the footpath made a
slight right turn a gate led in to an adjacent field on my left and this gave access
to another field where LIDAR places the summit of this hill. Aled had told me that there is a circular
livestock feeder at its high point, today this was just below the summit
looking a little forlorn.
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| The summit of Penrhos Garnedd |
The Trimble was soon
positioned at the high point gathering its allotted data, during which I stood
beside the adjacent hedge with the public footpath on the other side, and
looked out on the darkened Glyderau and Carneddau as shower clouds massed and
rainbows appeared against a deep grey sky.
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| Gathering data at the summit of Penrhos Garnedd |
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| The darkened Carneddau |
Once data were stored, I
packed the Trimble away and watched a helicopter rise in to the evening sky
from the helipad which I had investigated for a potential summit position on my
first visit to this hill. All that
remained was a fourth data set from the crossroads which I had visited an hour
or so earlier.
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| The emergency helicopter taking off from Ysbyty Gwynedd |
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| The top of Ffordd Penrhos as it intersects with Coed y Maes |
I positioned the Trimble
on a triangle of grass verge adjacent to the road intersection and gathered a
ten minute data set as buses and cars whizzed by, with cyclists and pedestrians
passing on the adjacent pavement, and non-looked at the Trimble as it beeped
away gathering its all-important data.
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| Gathering data beside the crossroads of Ffordd Penrhos and Coed y Maes |
As the Trimble did its
stuff I stood on the pavement a few metres away and watched the houses opposite
being illuminated by the evening sun as it sank in the western sky, and
considered whether this crossroads could be thought of as the summit of this
hill, as to my mind it has been terra-formed to the point that it would be hard
to judge what constitutes a semblance of natural ground.
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| The Trimble set-up position at the crossroads |
Once data were stored I
packed the Trimble away and walked the short distance back to my car before
visiting my brother and his wonky hip in the hospital.
Survey Result:
Penrhos Garnedd
Summit Height: 94.0m (converted to OSGM15, Trimble GeoXH 6000)
Summit Grid Reference: SH 56027 70234 (Trimble GeoXH 6000) (summit relocation confirmed)
Bwlch Height: 40.4m (LIDAR)
Bwlch Grid Reference: SH 56305 70029 (LIDAR)
Drop: 53.7m (Trimble GeoXH 6000 summit and LIDAR bwlch)
Dominance: 57.05% (Trimble GeoXH 6000 summit and LIDAR bwlch)
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