Wednesday, 24 February 2010

Places to map

As the weather improves we are all going to be out and about tracing roads for OSM. Larger towns and bigger areas that need attention are fairly well known, but as the amount of content on the map improves it can be difficult to find smaller and more local places where a short session could make a difference quickly.

So I've been messing around with OSM data again, trying to figure out a way to highlight areas that look as though they need some attention. The result is here.

This is very much a first cut, and it doesn't always get things right, but I think it gets them right often enough to be useful.

It starts with a list of about 1,600 UK settlements, and then uses a variety of techniques based on road density, type of road, and population to try and guess which settlements seem to have a lot of roads on the map for their size, and which don't have many. The green areas look as though they are well covered, and the red areas look as though they could do with some attention. The grey areas fall somewhere between the two.

There is more detail on how it works, and the subsequent discussion on the Talk-GB mailing list

It needs more work to improve the process, and a number of good suggestions are coming in on how to do that. I'd welcome more comments and ideas. But more important than perfecting the measurement is to get more roads on the map. So what I really hope is that this will help members of the community to find some handy places where they can quickly make a difference by plugging a few gaps.

Please remember though that this is a little bit hit-and-miss. It's probably a good idea to check some other sources as well before rushing out to your nearest red blob with the GPS.

Sunday, 21 February 2010


I'm always a bit surprised about the degree of fervour around browser preferences. I mostly use Chrome at the moment, but  I switch around a bit. Each has strengths, but for most purposes I can't see a lot of difference between them.

Apparently Internet Explorer is still the most widely used, accounting for around 60% of traffic. Firefox is second with almost 30%, then Chrome and Safari have around 5% each.  Opera, and the others make up the remaining few percent.

By contrast Firefox represents 48% of the traffic here, followed by Chrome with 24%, IE with 17% and Safari with 5%. The others make up the other 5%. My visits will be bumping up the Chrome figure a bit, but even allowing for that there's a distinct preference among Tlatet readers for the market challengers over the market leader.

It's an open question though whether that means we are more sophisticated, more free-thinking and independent, or just pig-headed.

Saturday, 20 February 2010


Around here the most noticeable gaps in the OSM map are in Bracknell, and today I decided I should go and try to fill some of them. My GPX trail, and the results are shown in the map above.

There has been some discussion on the Talk-GB lists about whether the locations suggested for this summer's mapping parties are going to be attractive enough, but there are also comments that in practice it doesn't make much difference. It wouldn't be difficult to be a bit sniffy about Bracknell as a mapping destination, but to my mind that misses the point. This isn't tourism. From home it's a pleasant ten mile ride out to Bracknell through the Walthams and Shurlock Row. When I got there, the residential areas that were missing weren't anything remarkable, but they seem pleasant enough. For me though, the real pleasure is in the ride. Mapping a bit of Bracknell is as good an excuse as any to get on the bike - with the added bonus that I'm not just trundling around - there is some purpose to the exercise.

As a relatively new town Bracknell is quite good at separating cycles and cars. There's a grid of fast roads, but then the residential roads are arranged so that they can't be used as rat-runs. On top of the road network  there is a network of footpaths and cycle paths so that people walking or cycling have access to plenty of short-cuts that cars cannot use. I imagine that it all works nicely for a local who knows their way around. But when you don't know the town it's a bit difficult to navigate on a bike. In practice the cycle routes seem quite fragmented and complicated, and the through roads are fast and busy. It seems to me that this should be an ideal environment for route finding with a GPS. A GPS should be able to get me from one side of Bracknell to the other, without needing any local knowledge. But there are currently lots of gaps in the map.

Today I was on the bike, but my intent was to plot roads. I didn't want to confuse the trace of the roads with paths that are restricted. So I didn't trace all the connections that were open to bikes. As a result, anyone who uses my contribution to route-find on a bike could be taken around some unnecessarily convoluted journeys. There are probably ways that I could have done this better, and I should give it some thought. In the meantime, there are a few more miles of residential road in north-west Bracknell that weren't on the map a few hours ago - but I'm conscious that I've only contributed part of the data that needs to be added.

When I did the editing, I was reminded that although I've added the odd detail to OSM from my trips over the lest few weeks, and I've edited some content from NPE, I haven't added any significant traces since before Christmas. It's a bit of a call to action, and there are still some gaps to fill in Bracknell.

Capital smooth and hard road

The A4 is a historic road in England, which runs from London to Avonmouth, near Bristol. It was the main route from London to the west of England. As here in Maidenhead it is known for much of the way as the Bath road. It did originally only run as far as Bath, but in 1935 the A36 between Bath and Avonmouth was renumbered as the western end of the A4.

The heyday of the road was in the nineteenth century as a coaching route, up until the arrival of the Great Western Railway, which reached Maidenhead from London in 1838, and linked London and Bristol from 1841.

In 1821 mail coaches were averaging 8.75 mph along here between London and Bath (including stoppages). That's about the same speed as I average over a full day on the bike (including stoppages). They left London at 8pm, and reach Bristol the following morning at 10am.

Fast passenger coaches (stage coaches) were reaching 11 mph or more, and by 1837 there were fifteen passenger coaches a day between London and Bath, as well as two mail coaches. From then on, as the railway extended out towards Reading the start point of the coach journey moved nearer to Bristol, and once the railway was complete the coach services ended.

This picture was taken just east of Maidenhead Thicket, which along with Hounslow Heath (roughly where Heathrow Airport is now) was one of the notorious spots where coaches feared an encounter with highwaymen. The highwaymen at Hounslow heath would target rich travellers going from London to Bath, while those at Maidenhead would target those travelling from Bath to London. Nevertheless, Maidenhead was a popular overnight stopping point for those travelling west who preferred to cross the thicket early in the day (presumably while the highwaymen were still having breakfast).

"The roads of England and Wales: an itinerary for cyclists, tourists, and travellers, containing an original description of the contour and surface with mileage of the main direct and principal cross roads in England and Wales, and Part of Scotland" (which is a blinder of a book title), has this to say about the road between Maidenhead and Twyford in 1898 - "hill to mount out of the town, then first rate level road to Stubbings Heath or Maidenhead Thicket, and the rest is rather hilly by Littlewick Green, Knowl Hill, Kiln Green, and Hare Hatch; capital smooth and hard road. Pretty scenery".

Since the early 1960's the A4 between Maidenhead and London has been been paralleled by the M4 Motorway, which extended as far as Swindon in the early 1970's.

And now, having shifted traffic off onto the railways, and the motorways they are going to cap it all by building a cycleway. It's all part of the local authority plan to encourage pupils to cycle and walk to school, and they hope it will also reduce congestion and parking problems. It involves some new cycle paths, and signage.

I applaud the policy of encouraging cycling. And as I regularly face the problem of crossing this part of the A4 at busy times of day I look forward to the end of March, when I can change my route slightly so that the new toucan crossing speeds me on my way.

Charles Harper - The Bath Road =

The roads of England and Wales =

Society for All British Road Enthusiasts =

Motorway database =

A4 Cycleway =

Thursday, 18 February 2010

Road densities on OSM

This is one of those things that you do, then you are not quite sure whether it was worth it or not.

I calculated the road density for each of the "Pay scale areas" that arrived with the OSM Naptan import. I thought that these would be fairly thickly populated areas, so a low road density would highlight places where there were roads missing from the map, and hence help to prioritise more attention.

Road density is calculated as the length of roads in km, divided by the area in sq. km. I've included motorways (and links), primary, secondary, tertiary, unclassiifed and residential roads. I've not included cycleways, paths and bridleways, etc.  The data extract I used is actually a few weeks old, but that shouldn't make a lot of difference (unless someone has added a mass of new roads in a particular area).

The highest quartile of areas (by road density) are shown in blue, then the following quartiles in green, orange and red. In other words red areas don't have many roads for the area, blue areas do.

Looking at the result, things obviously are not as simple as I expected. Anyway, for what it's worth, this is what it looks like. Maybe someone else will spot a way of making use of the information.

Monday, 15 February 2010

Cycling participation

I missed this when it came out in December, but better late than never. Sport England published the results of their Active People Survey including a factsheet on Cycling, which is here. The full list of diferent sports is here.

On the basis that they surveyed (at least one 30 minutes session of at least moderate intensity per week) cycling ranks as the third most popular participation sport after swimming and football, but ahead of athletics. Cycling is more than twice as popular as golf, from which I gain some satisfaction.

It looks as though in 2009 1,880,0004 people cycled at least once a week (4.50% of the adult population), which is an increase from 4.26% a year earlier. The increase was almost entirely accounted for by men in their early 20's, and late 30's to early 60's. There was significant growth in cycling in the North East and South West of England. The proportion of cyclists engaging in competition or tuition is relatively stable, but club membership has increased.

Sunday, 14 February 2010

Result of a rainy weekend

It's been a rainy weekend, so I've not been out on the bike. Instead I've been playing around with OpenLayers, trying out an idea suggested by Richard Fairhurst that shows how scale varies when you plot a round planet on a flat screen. I've made some progress, and I think this illustrates the idea. It's all a bit clunky under the hood, though, because I'm still climbing a steep learning curve on how all this stuff works. If this weather continues I might get a chance to refine it a bit.

I've started to make a few improvements.

For one thing, it's now possible to configure the units used (as "metric" or "imperial") and the colour (using the standard html colour set = aqua, black, blue, fuchsia, gray, green, lime, maroon, navy, olive, purple, red, silver, teal, white, and yellow, plus browser dependent alternatives). Using darkblue matches the OSM controls.

Our former colonies should note the English spelling of the "colour" parameter.

"How would we have done that in Cobol?"

Years ago I used to earn my living as a Cobol programmer. At one stage I even met Grace Hopper. Things have moved on a long way since then, but the lessons that I learned in the early days have sometimes kept me grounded in an industry that (shall we say) has a bias towards optimism.

Rob Bryden has said that "with any moral dilemma I always ask myself, what would Rod Stewart do?". Well, when I'm trying to understand some new piece of software I can't help wondering "how would we have done that in Cobol?". In the past it wasn't such a bad place to start, but there are things going on now that go well beyond the point where my simple test breaks down. I'm not sure that knowledge of Cobol would help a lot with understanding how they do this stuff, and I doubt if Rod Stewart is going to be much help either. But on the other hand, how well would this clever stuff handle a general ledger?

(thanks to Mapperz, and others for the link)

Saturday, 13 February 2010

Surrey: an apology

When I was growing up in north-east England we were taught to recite the following ditty. The idea, I suppose, was to cure us of short northern vowels.  For the full effect you have to pronounce the a's as though they are spelt "ar" ("rarther farst" and "parst")....

My father's car is a Jaguar
And pa drives rather fast
Castles, farms and draughty barns, 
We go charging past

In retrospect it seems very odd. Nobody can have expected us to pass ourselves off as being posh, but perhaps the plan was that we could  mix with the officer classes without causing embarrassment. It was never going to work, and thankfully society moved on anyway. We learned from the Beatles how to do a much better imitation of a Liverpool accent, and if there's anyone still around who talks like Celia Johnson or Trevor Howard then they are keeping their distance.

However, that little ditty, together with the schoolboy reading of the time left me with some very confused ideas about the south of England. I imagined that in the south boys my age all boarded at minor public schools, and understood the mysteries of cricket. Their little sisters rode ponies, their father (who they called pater) had a slightly shady job in the city, drank g&t at the golf club (before driving home in a Jaguar, rather fast), while their mother was having cucumber sandwiches with the vicar. They all lived in large mock-tudor mansions in villages full of little old ladies on bicycles who solved murders while spitfires flew overhead.

Inevitably, as time went on my knowledge of the world expanded, I met people from the south of England who didn't wear cravats, and who could drive in the snow. I discovered parts of southern England that weren't as I imagined, and eventually I sold my northern soul to the devil, and followed the job down here.

As a result I can now say that some of my best friends are southerners. Not many of them, of course. Most of my friends are lapsed northerners like myself, or expatriates from exotic and faraway places such as Scotland. The only southerner I know really well is from Essex, and that counts as East Anglia anyway. But lets not get bogged down in detail.

The important point is that I now know that Kent isn't like the southern England that I imagined, and neither is Sussex. Middlesex doesn't even exist any more - it turned into an airport. So all of my prejudices ended up concentrated on Surrey. I knew virtually nothing about it, so in my mind it was the last bastion of southern-ness.

And then along came my Jenkins quest, which forced me to visit the county, and threw my pre-conceptions into disarray. I've made a couple of trips on the bike to Surrey now, and discovered that the bastions are not as I imagined.

Perhaps there is really a heritage centre somewhere where all the minor public schools, jaguars, golfers, and ponies are still preserved, and people dress up in cravats and talk as though they are performing in a black-and-white film. But if such a place does exist I haven't discovered it yet. The parts of Surrey that I've visited are quite ordinary.

So unless anyone can point me in the right direction, this is by way of an apology to Surrey for years of imagining that it was weird. I'm sorry, and in future I'll try to be more sensible.

Wednesday, 10 February 2010

Tuesday, 9 February 2010

Medieval stained glass

All Saints at North Moreton was one of the two churches that I visited on Saturday. Saint Andrew, at East Hagbourne was the other. Both are close to Didcot.

All Saints has been described as the most perfect medieval church in Berkshire. Which is a little odd, given that it is in Oxfordshire. It isn't the church that has moved. It's the county boundary, which was shifted in 1974 (on April 1st), when Didcot and Wallingford became part of South Oxfordshire.

All Saints is a nice enough parish church, with one outstanding feature. The stained glass in the Stapleton Chapel dates from the late thirteenth century, and even to my uninformed eye, it looks superb.For something that it is over 700 years old, the colours are stunning.

Unfortunately Saint Andrew's church at East Hagbourne was closed when I got there, so I didn't get to see the carvings, which apparently are the highlight.

My route outwards was via Henley and Wallingford. I started along the back roads to Henley, but for the sake of speed I then followed main roads. It's quite a long climb out of Henley, so at that stage I was getting quite warm, but then the temperature dropped noticeably as I descended through Nettlebed to Wallingford in a bit of light fog.

Coming back I followed National Cycle Route 5 across the hills through Stoke Row to Reading, then I crossed Reading along the towpath beside the river. The subtle colours of blue and grey along the river in the dusk were striking, but by the time I came out of Reading it was getting dark and from there I just bashed along the main road to get home.

In the past I've never managed to follow cycle route 5 coming into Reading, because I drifted off route by missing a turning. As a result I've ended up negotiating some busy roads. This time, thanks to the OSM cycle map on the GPS (and, I suspect, some better signage out on the road) I managed to follow the Sustrans route properly.

It's a fun ride, diving down little lanes, and around a park to join the river at Caversham bridge. I found it a big improvement over my previous attempts to cross Reading, and a much more interesting way to get from one side of the city to the other.

All of the roads that I followed were already on the OSM map, but neither of the churches were, so I've now added them. It's getting harder to find places locally that need mapping, but since I got home I've noticed that there are some missing minor roads quite close to the route that I followed. Next time I need to plan some short diversions to plug a few gaps.

Sunday, 7 February 2010

"Cycling may be dangerous to people coming out of church"

There are two things that need to be said up front.

One is that I don't normally cycle in churchyards. I'm not sure that I can explain why, but even sticking to the paths, it does feel disrespectful to cycle through a graveyard. So normally when I am visiting a church on the bike I get off at the gate, and I push.

The second thing to point out is that at the church where I took this picture there is a footpath that crosses the churchyard. It runs close to the church door and it seems to be quite heavily used.

So placed in context, the sign makes a lot of sense, and I'm all in favour of the spirit that lies behind it.


In the different context of the more bizarre attacks on cycling and cyclists, I find the idea that "cycling may be dangerous to people coming out of church" quite funny. And I offer this up in that spirit.

Saturday, 6 February 2010

Jethro Tull's cottage, Crowmarsh Gifford

I hope there is a debate going on somewhere in the OSM community about how best to tag buildings associated with people whose name was subsequently adopted by a progressive blues-rock group featuring a flute. Unfortunately I didn't record the precise location of this building, so I'm in no position to contribute.

To my generation Jethro Tull are a British group, best known for "Living in the Past", "Aqualung", and Ian Anderson standing on one foot while playing the flute with his hair in disarray. This is not the cottage in Crowmarsh Gifford, where members of the group have lived since 1967.

Jethro Tull (1674 – 1741) was an English agricultural pioneer. He improved the seed drill ( a device for sowing seeds), while living in this cottage between 1700 and 1710.

Thursday, 4 February 2010


This evening I've discovered from Mapperz that the British Geological survey publishes KML files of UK geology.

I thought it would be interesting to see if these could be overlaid onto an OSM base map. If you are patient enough, they can.

The file is in KMZ format, which I couldn't get to work, so I've de-compressed it to extract the KML content. But be warned, there is more than 17mb of data being shunted around here, so everything moves very, very, very slowly.

Even in this condition, I think it is worth the effort. It's beautiful and fascinating, as I hope the image shows. At least for now, you can view the whole shebang here (eventually). I hope you find that it is worth the wait, and maybe somebody more skilled than I am can figure out how to make it all happen a bit faster. Meanwhile, start it up, then go and put the kettle on.

Monday, 1 February 2010

Glass half full

One month of the year is over, and so far I've covered 211 miles on the bike. That's more than at this time last year. Come to that, it's more than at this time the previous year, though two years ago I'd only had the bike for a few days, so it doesn't really count.

I've only done five trips in January, but three of them have been over 60 miles. That's far enough to be over my comfort level, but it hasn't had a big effect on my Eddington number yet. It does mean that I'm banking some trips that should be useful later in the year though. I've also ticked off visits to four of the churches that are on this year's list of fifteen to visit on the bike.

All that's on the positive side of the scales. On the other hand, if I'm going to reach my annual target I've got to average nearly 300 miles a month, so there's a bit of a gap building up. Also, I've not added anything significant to Open Street Map yet this year (all the routes that I've ridden in the last few weeks had already been added).

Last year it was at this point in early February that things began to drift off-plan, and it took me a couple of months to get back on track. So while I'm not unhappy with how things are going at the moment, the next few weeks are going to be telling.