Yellow roads and black numbers.

NATURAL ANKLING · Post by **NATURAL ANKLING** » 5 Mar 2018, 10:58pm

Hi,
If that's an online map, you have to zoom in............something like that.........apparently its a glitch.................

Post by **Mick F** » 6 Mar 2018, 6:37am

The map is wrong ............ but that's not unusual, I suppose.

The spot height isn't next to the place of worship, but maybe 50yds further down the hill. I saw it only a week ago walking home down Chapel St.

It's actually here. Nice big black blob to show.

: Gunnislake 1-25k spot height.png (171.54 KiB) Viewed 902 times

Tangled Metal · Post by **Tangled Metal** » 6 Mar 2018, 8:29am

Map nerds, dontcha just luv em! :wink:

Keeps them off the railway stations I suppose!!! :wink:

elPedro666 · Post by **elPedro666** » 6 Mar 2018, 6:57pm

Tangled Metal wrote:Map nerds, dontcha just luv em!

Keeps them off the railway stations I suppose!!!

But what does that make us even sadderos that are just enjoying listening in?! [emoji23]

I'm a trendy consumer. Just look at my wobbly using hovercraft full of eels.

fausto copy · Post by **fausto copy** » 6 Mar 2018, 7:30pm

Richard Fairhurst wrote:
crabbit wrote:Can someone help? When looking at OS maps there are black numbers at regular intervals alongside yellow roads. Are these altitude indicators for the roads height at that point?

Yes - these are "spot heights" (and indeed you'll see a little black spot on the road, if you look closely).

I originally thought they were potholes, but as the new maps don't have any more than the old ones, obviously not the case. :lol:

Incidentally, when we were cycling in the Cirencester area, specifically roads over towards Bibury and Burford, I kept noticing metal discs in the tarmac at the side of the roads. I couldn't establish if they were equidistant from one another, so not sure if they were a measurement indicator.
Can someone please enlighten me?

fausto.

Grarea · Post by **Grarea** » 6 Mar 2018, 8:19pm

Boy I am glad I looked in this evening.
Now I know something that I didn't even know I didn't know.
You know?

foxyrider · Post by **foxyrider** » 6 Mar 2018, 8:39pm

fausto copy wrote:
Richard Fairhurst wrote:
crabbit wrote:Can someone help? When looking at OS maps there are black numbers at regular intervals alongside yellow roads. Are these altitude indicators for the roads height at that point?

Yes - these are "spot heights" (and indeed you'll see a little black spot on the road, if you look closely).

I originally thought they were potholes, but as the new maps don't have any more than the old ones, obviously not the case.

Incidentally, when we were cycling in the Cirencester area, specifically roads over towards Bibury and Burford, I kept noticing metal discs in the tarmac at the side of the roads. I couldn't establish if they were equidistant from one another, so not sure if they were a measurement indicator.
Can someone please enlighten me?

fausto.

They sound like fixed survey points - they may be used to check calibration of EDM's/ Dumpies but not exclusively. There are examples on roads all over the place although they are more common in rural areas - not sure who installs them mind.

drossall · Post by **drossall** » 6 Mar 2018, 9:04pm

Spot heights are fixed points with known heights, closely related to trig points - but, unlike trig points, spot heights aren't necessarily marked on the ground. Putting them in random places makes them hard to locate precisely, so points along roads, footpaths and so on are sensible. High points are also used - not necessarily the absolute top of a hill, but somewhere prominent, since the point is to be able to see it when triangulating. Roads tend to avoid high points, so hjgher spot heights will typically be in open country.

If you use a map with lots of roads, it will appear that all spot heights are alongside roads. If your map shows a more remote area, you'll get them in open country too.

Flite · Post by **Flite** » 6 Mar 2018, 9:41pm

I think spot heights have been accurately determined, and are marked in the terrain by a "bench mark".
Bench Marks are usually carved into buildings and look like an arrow pointing up with a bar on top.
Government property, like prison clothing used to be marked.
We've got a bench mark on our house

Cyril Haearn · Post by **Cyril Haearn** » 6 Mar 2018, 9:45pm

Flite wrote:I think spot heights have been accurately determined, and are marked in the terrain by a "bench mark".
Bench Marks are usually carved into buildings and look like an arrow pointing up with a bar on top.
Government property, like prison clothing used to be marked.
We've got a bench mark on our house

Are you still im-prisoned by snow?

I thought the OS had modernised and no longer used trig points and the like
Triangulation and surveying really are fascinating, I love reading old 1:63 360 maps when I can not concentrate on a book
Heights not surveyed by levelling were shown in italics (how were they surveyed?)

drossall · Post by **drossall** » 6 Mar 2018, 9:53pm

Correct, I believe that the OS don't use them any more. But they are still there.

We started cycling as teenagers by my friend purloining his Dad's set of 1:63360 maps. His Dad was annoyed as he was proud of his complete set of the country, and they didn't benefit from being stuffed in a jersey pocket.

Later I managed to assemble a complete 1:50000 set. Just as digital maps came in and made them irrelevant.

thirdcrank · Post by **thirdcrank** » 6 Mar 2018, 10:02pm

Were there ever people who referred to 1" to a mile as 1:63360?

If ever there was a case of dumbing down it was when the OS decided to start producing maps for people who never paid attention in geography lessons. (I've inserted a new paragraph as these random musings are not connected.

Paulatic · Post by **Paulatic** » 6 Mar 2018, 10:18pm

thirdcrank wrote:Were there ever people who referred to 1" to a mile as 1:63360?

If ever there was a case of dumbing down it was when the OS decided to start producing maps for people who never paid attention in geography lessons. (I've inserted a new paragraph as these random musings are not connected.

When we got maps out at school that was probably the only time they had my full attention.

Later in the cadet force we got a map each to play with complete with compass. Happy Days. Also how to find south with your wrist watch.
Now I just get my phone out which is probably more accurate than some f my map reading :lol:

drossall · Post by **drossall** » 6 Mar 2018, 10:31pm

thirdcrank wrote:Were there ever people who referred to 1" to a mile as 1:63360?

Well there are at least two of us upthread

Although you're right, I might say 1" to the mile more often.

I came to love maps at Scouts. Before an Audax, I'll look through the whole route on the map. And then still sometimes be vague about where I'm going :roll:

elPedro666 · Post by **elPedro666** » 6 Mar 2018, 10:40pm

drossall wrote:Before an Audax, I'll look through the whole route on the map. And then still sometimes be vague about where I'm going

Sounds as though you have that perfected to me [emoji6]

I'm a trendy consumer. Just look at my wobbly using hovercraft full of eels.

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