Explore the Outdoors: Part 1 – Benchmarking and Trigpointing

Geocaching is probably the most popular location-based game out there. For me, nothing could possibly take the place of the thrill of finding secret “treasure” hidden right under everybody’s noses. Although I’ll quite happily chat to muggles or friends about Caching, there is still the excitement of it not being a well-known thing and that you are on a little “secret mission” to unearth the treasure! But I thought I’d broaden my horizons and take a look at some of the other GPS games/location-based games out there and the other caching sites and see what I might be missing out on. This was going to be quite a brief post, but as I discovered so many different hobbies and games that I thought I’d expand it into a bit of a series. Are you tempted by any of these Geocaching alternatives? Or do you participate any others already? Drop a comment below!

Part 1 in the ‘Explore the Outdoors’ series looks at Benchmark hunting and Trigpointing.

Benchmark Introduction

If you log onto your Geocaching.com profile you will notice at the top right next to ‘Souvenirs‘ you have a ‘Benchmarks‘ link. Follow this and you will find your logged benchmarks and if you are a UK user you will probably find nothing. To start finding Benchmarks you need to navigate to the Benchmark Hunting page and if you are a UK user you will probably find…Wait for it…NOTHING! Search for somewhere in the US however and you’ll be much more successful

A benchmark in New York

Unfortunately Benchmarking on the Geocaching.com website isn’t available in the UK due to the Benchmarks for Geocaching.com coming from a US database.

Fear not, however as we have Trigpointing and our own UK Benchmark database. The only slight hitch is that this isn’t liked to Groundspeak at all, so your logs and find numbers are completely independent. There is also Waymarking, which is linked to Groundspeak that I will look at in a different entry. I think it’s time to explore my options…

UK Benchmarks

“Benchmark” is a surveyor’s term for horizontal chisel marks made in stone. Into these an angle-iron could be place to form a “bench” for a leveling rod so that they rod could be positioned in the same place in the future. There is usually an arrow chiseled below the line.

An example of a cut benchmark

The UK Benchmark database is also available on a website. It seems that all Benchmarks are loggable except for trig points. I quickly joined up and did a search for a ‘Cut benchmark’ that I noticed in Trafalgar Square on a plinth for a statue at the Ostra Antigua earthcache. I couldn’t find it in the database however, so maybe it’s just not listed, or maybe I wasn’t using the right search terms.

There are quite a few different types of benchmarks in the UK database.

Flush Bracket

Along levelling lines between fundamental benchmarks are Flush Brackets. These are metal plates cememted flush to the face of a building. Each Flush Bracket is approximately 1 mile from another. Each bracket has a serial number on it. They are often fised to triangulation pillars, however the ones that aren’t are known as “Non-Pillar Flush Brackets (NPFB)”

Bottesford Flush Bracket S8789 (Brian Westlake) / CC BY-SA 2.0

Fundamental Benchmark

Fundamental Benchmarks are highly accurate, stable height stations that are still in current use today. They are constructed approximately 25 miles apart and consist of a buried chamber with a brass bolt in the top of a granite pillar.

Bishopston's Fundamental Benchmark's detail (Hywel Williams) / CC BY-SA 2.0

Projecting Benchmark

Projecting Benchmarks are metal brackets that were used briefly before flush brackets. They are all identical.

Ordnance Survey benchmark on Hellifield Institute (Roger Templeman) / CC BY-SA 2.0


When it there wasn’t a convenient vertical to place a G-Series flush bracket on a building or wall, these domed 1″ diameter metal bolts were fixed to horizontal surfaces. They have OSBM engraved on them along with the benchmark symbol.

Dunvegan Head Bolt Bench Mark - detail (Richard Dorrell) / CC BY-SA 2.0

Pivoting Benchmark

Similar in appearance to Rivets, however these are seen on horizontal services where inserting the rivet would cause the stone to break. e.g. Soft sandstone. They look like a normal benchmark, however at the top of the arrow there is a small hole or depression cut in to take the pivot. The pivot is then placed in the depression for measurements to be taken. These are fairly rare.

Pivot benchmark#2 on Porth Penrhyn dock wall, Bangor (Meirion) / CC BY-SA 2.0

Tidal Observatory

There are only 3 of these in the entire database, however they are very important. Newlyn Tidal Observatory was established to determine the mean sea level that is the starting point for levelling in the UK. This brass bolt is the benchmark for the whole of the United Kingdom, that is, all heights are referenced to this point.

Bidston Observatory (Sue Adair) / CC BY-SA 2.0

Cut Benchmark with Bolt (1GL)

These are very old and rare and have a metal bolt screwed either alongside the horizontal line, or at the point of the arrowhead.

Bench Mark , St John the Baptist, Achurch (Michael Trolove) / CC BY-SA 2.0


These are similar in appearance to Pivoting Bench marks, however there is a small metal brass rivet at the apex of the arrowheads.

Rivet benchmark on Maelgwyn Road, Llandudno (Meirion) / CC BY-SA 2.0

Triangulation Pillar (Or Trig Point)

A concrete or stone pillar placed at intervals around the country. They were once used for map surveying, but are no longer needed. They were placed so as to be in sight of each other, so many are on hills or mountains. These are not loggable on this bench mark database, and have their own dedicated site where they can be logged.

Overstones Triangulation Pillar (Jonathan Clitheroe) / CC BY-SA 2.0

Using the Benchmark UK database

It’s quite easy to find a benchmark using the website as there are quite a few options that you can search using. As I said I couldn’t find my Trafalgar Square one that I spotted, however I did find one on a milestone along a road that I’ve run along many times.

Searching for a benchmark

Results from a search

I checked my running diary and found a date when I would have run past it. After signing up to the website I was quickly able to log this as my first benchmark find! πŸ˜€


And that’s it. It’s pretty easy to log a find and there are literally hundreds of benchmarks near you that you probably never would have even noticed.


Logging Trig Points can be done at TrigPointingUK.com! I had a quick think back to 3 caches. 2 of these were at trig points (I remember one very well as I extracted the film can from the hole and a huge nest of ants and ant eggs came with it!!!), and for 1 I remember passing it on the way back to the car recently. I tried searching for nearby Geocaches and towns using the search facility and yielded nothing so I whizzed on over the http://maps.the-hug.net and quickly located the trig points that I saw. It’s easy on the ordnance survey maps there to click on a trig point that you can see on the map and pop up the grid reference. You can then enter this into the trig point website search box and the closest trig points will appear.

Nice list, shame about the background colour

I’m now feeling rather proud of myself as I have found 3 trig points and I can also reliably log the date that I found them because it is the same date that I found the caches! πŸ˜€

My trig point finds are:
TP2048 – Catley Park
TP7125 – New Farm
TP4887 – Monkhams Hall

There’s a neat little map of the UK that shows you the blue dots of trig points, and the ones that you’ve found as red dots. Despite the colours of the website, I really like it.

I've got a long way to go...

It’s a neat idea and something that I think I could get into, but probably not quite in the way that I am in to Geocaching. It looks like quite a few people do it, and there are a few Geocacher usernames that I recognise in the logs for trig points. There’s also the ability to upload photos of the trig points and the pages for the ones that I visited did have quite a few photos on them.

For some more examples and photos of UK benchmarks check out the geograph website.

In my next post ‘Explore the Outdoors: Part 2 – Waymarking’ I shall look at Groundspeak’s Waymarking site, the site that is often referred to as the place where virtual caches belong…


10 Responses to “Explore the Outdoors: Part 1 – Benchmarking and Trigpointing”

  1. jane Says:

    I used to follow this geodashing game
    Never had the chance to find one but use to like reading other peoples reports.

  2. ErikaJean Says:

    That was kind of neat to see how your benchmarks are different!

  3. Caching with Friends « GeoCass UK GeoCaching Says:

    […] we passed by a farm to bump into what I thought was a trigger point after I’d written my previous blog post about discovering them. I jumped in front ready for my photo taken. It was surrounded by a fence […]

  4. Explore the outdoors: Part 2 – Waymarking « GeoCass UK GeoCaching Says:

    […] part 1 of Explore the Outdoors I looked at Benchmarking and Trigpointing. In Part 2 I take a look at […]

  5. Explore the outdoors: Part 3 – Geocaching.com alternatives « GeoCass UK GeoCaching Says:

    […] my previous “Explore the Outdoors” posts I have looked at Waymarking and Benchmarking/Trigpointing. In this installment I take a look at alternative cache listings […]

  6. N!TR0 Says:

    Hi, I’ve been making a overlay map with the current OS raster maps using the old BM data. It gives a map with identifying makers for where they are over a 5km square. Would any maps be any use to you?

    N!TR0 – on GC and WM sites.

  7. All that we survey | BrownhillsBob's Brownhills Blog Says:

    […] There are a variety of different benchmarks, brackets and studs in use; their identification and usage is explained in this great link supplied by Peter ‘Pedro’ Cutler, who’s also a bit of an OS aficio…. […]

  8. Tony H Says:

    The OS Benchmark database is very useful for identifying BMs that have not been logged on Bench-Mark.org. The web address is: http://www.ordnancesurvey.co.uk/benchmarks/

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