Amersham Circular
WALK
FEATURES

28 February 2016


Where ? Map Heights Figures Extra Timing Track Finally Read Me



Features of Our Walk around Amersham

This walk of about 8⅔ miles (approaching 14 Km) was ably led by John (Churchill) one of our CLOG stalwarts and Chiltern aficionado. The heights stayed within a band of 95 to 171 metres, and with a total ascent and descent of 193 metres. The average up and down gradients of about 4% for about 3 miles and 3½% over about 3⅓ miles were greater than usual on many CLOG day walks, but par for the course in the Chilterns, and certainly ensured that we had plenty of interest and good exercise.



Towards the end of our walk we had a fine view over Old Amersham. It may have involved the steepest ascent of the day, but all was grist to the mill for seasoned CLOGgies!

Walking weather was favourable, with a "guesstimated" average temperature of about five degrees Centigrade. We had sunshine and some clouds throughout the day, but not a drop of rain. Indeed, John picked a good Sunday which gave an excellent respite from the inclement weather on the day before. It was possible to complete our walk comfortably within the daylight constraints at this time of year, even with a pub lunch stop in Hyde Heath and another tea stop in Amersham.

Now prepare ye for some plots and graphs. Not too overwhelming, but hopefully quite interesting! You will see here:



Where is Amersham?

Where is Amersham - or at least the station? As if you didn't know! Well, let's make with the goods. We said that Amersham Station, our starting point, is about 37.95 Km (23.58 miles) from the centre of London. These figures are based on a bit of Spherical Geometry and an associated Excel® calculation. The centre of London is taken as Charing Cross which is the intersection of The Strand, Whitehall and Cockspur Street, not the Victorian Eleanor Cross itself (as you might have guessed, Cromwell destroyed the original cross or at least, had it destroyed) nor the station in front of which it stands. The distance is a great circle route, as the conceptual crow flies. In addition, Amersham Station is 0.167° north and 0.479° west of Charing Cross. Now, using the resolution of a 16-point compass scale, this makes Amersham Station approximately "West North West" of the centre of London. All just in case you are interested!!



Outline Map of Our Walk

Our walk was "anti-clockwise circular" with the steepest climb just before we came back to Amersham Station. The map grid scales translate to 1.112 Km per 0.01° latitude and a mean of 0.689 Km per 0.01° longitude, all when using 6371.0 Km as the volumetric mean radius of the earth - as per the WGS84 standard! Interestingly, to the south, in Otford, Kent, we already have 0.695 Km per 0.01° longitude instead of 0.689 Km per 0.01° longitude; the further south you go, "the more bangs per buck", or, in more down to earth lingo, the more distance per given degree change in longitude! It's not that much, but certainly registered in the calculations and accords with what one could expect.


Outline Map of Walk

I plotted our walk by hand on my return home. Of course, I tried to be reasonably accurate. Even OS maps, on which I based my plot, may not show all the required detail, but appear to give the requisite degree of accuracy in this case.

Because we don't live on a flat earth - unless you are a convinced "flat-earther" - maps are inevitably a distortion of what is. In other words, it's all a matter of mapping a curvaceous surface onto a flat surface. We don't want to carry curvaceous representations of the terrain on our walks, do we? In our case, the northern length of our map grid is stretched out by something like an extra 0.09 %, to make it the same on the page as the length of the southern part of our map grid. Not that much for hiking purposes really! Can't complain.



Height Profile of Our Walk

It's of course fine to say that we reached about 171 m above sea level and descended to 95 m above sea level, but what's the significance of that? Probably, of greater interest, when it comes to considering personal achievements, is the total ascent - which usually requires greater effort than the descent. On today's walk, the total ascent was 193 m, which as expected, was greater than the difference of 76 metres between maximum and minimum heights above mean sea level.


Height Profile

The above plot uses a true origin for the vertical elevation (height) axis, so as not to lose track of reality. What a worthy aim!

As you can see from the plot, we had a very steep ascent towards the end of our walk, behind Old Amersham Church. More about that a bit further below.



Some Facts and Figures

Here are some "vital statistics" in metric and imperial units. The total length of the walk is measured on a conceptual "flat" plane at mean sea level, WGS84 style. Of course, as mentioned above, the total ascent exceeds the difference between maximum and minimum elevations; I'd suspect things, if the reverse transpired!


"Walk facts and figures"


Average Rising and Falling Gradients

And here, for the numerical fun of it, are the average gradients we overcame on our walk. The rising and falling (negative) gradients are both averaged over the distance given, with level stretches having rises and falls of less than ± ½ metre.

We may be speaking about average gradients, but for 400 m behind Old Amersham Church, as we were getting close to Amersham Station, we experienced a gradient of about 12¼ %. I suppose, at the end of our walk it didn't feel that steep. Perhaps a case of mind over matter and, of course, being seasoned CLOGgies, used to such things!


Rising and Falling Gradients

By comparison, Hertfordshire County Council recommends that its roads should not have longitudinal gradients of more than 5% and one of the steepest adhesion railways in the world, in Austria, has a maximum gradient of 11.6%. By way of further interest, the clockwise route of the Fairfield Horseshoe in the Lake District has a total distance of 15.62 Km (9.71 miles), with the following calculations: an average rising gradient of 14.66% over 6.589 Km, a level part over 0.345 Km, and an average falling gradient of 11.11% over 8.676 Km. This is seen by many as really quite challenging - but then, when you compare it with our walk, it can be said that we had a more leisurely and less demanding aim compared with Lakeland challenges!



Weather, Ground Conditions, Signposting

On any walk there are considerations which are very real but tantalizingly out of ready reach of those who wish to espouse a numerical approach to many of life's activities. Here are three considerations for starters.



Timing and Speed

It's one thing to discuss the terrain over which we walk. It's quite another to ask how we personally respond to walking over that terrain. There are a number of considerations, of which timing and speed can be taken as starting points.



Track File

If you are keen to see our walk superimposed on an Ordnance Survey® (OS) map or on another system such as Google Maps®, then you can use the following file to do so. As mentioned above, the numerical data in this file have been hand-plotted by me (no GPS!) on my return home. The data are based on WGS84. Of course, for copyright reasons, I do not show the OS-based or Google-based maps here.



Postscript

Any map is an approximate representation of what is, and my plotting thereon certainly is. Practicality and scale are relevant considerations. We are not dealing with a planning application calling for detailed spatial descriptions of intricate boundaries. For us in the hiking community, the degrees of accuracy and precision should be just enough to give us useable and helpful knowledge of the terrain about us and beneath our feet. I hope my humble endeavours on this page are in this respect interesting for, and useful to, you my reader!