Bug in Google maps' support for Eircodes

Ireland introduced a postcode system called Eircode relatively recently in 2015. Controversially it is not possible to map from an eircode to a GPS location without lookup on the Eircode Finder web site. The good news is that Google maps service supports eircodes and does the lookup for you behind the scenes. However, the bad news is that Google has a subtle but significant bug in the way that the Google maps works with eircodes.

The best way to understand the problem is to look at a practical example.

The example I will use is the address "12 Maunsells Park". If you search for this address Google will thankfully translate the address to "12 Maunsells Park, Galway, H91 AVW8, Ireland" where "H91 AVW8" is the eircode. If you ask for directions to this address it will correctly navigate you to the front door.

This is all good. However, the problem happens if you decide to instead search for the eircode  "H91 AVW8" (many delivery drivers prefer to search for the eircode because it is shorter to type and is unambiguous). At first glance this seems to work, because the dot appears at the same point in the map. However, if you try navigate to the point you will run into problems. 

The problem come from the fact that there is a small lane called "Maddens Lane" running behind the property. This small lane is lined with trees and a tall wall - there is no easy way to get from "Maddens Lane" to "12 Maunsells Park". However, since the dot on the map is slightly nearer to the back of the property, Google incorrectly decides that is where you want directions to.

If you route from one to the other Google says it is a 5 minute walk with three turns as you can see from the screenshot below.

This might seem like a minor nit-pick, but the reality of the situation is that people with a property between two roads like this will frequently dealing with delivery drivers ringing up to say they can't find where to deliver their package.

Understanding the problem is easy, implementing a solution is less obvious. One solution would be to update latitude/longitude in the eircode database to put the dot nearer the entrance to the property. However eircode support neem to be reluctant to do this.

More challenges to navigating around dublin

Visitors (and even locals) often find it hard to navigate around Dublin. One of the problems the strange custom in Dublin of assigning totally different names to different sections of the same road.  I blogged before about some of the more confusing examples of this. Another problem is the fact that the council regularly decide to change the name of a street.

Here are a few examples:

1. Amiens Street was The Strand 
2. Ardee Street was Crooked Staff 
3. Aughrim Street was part of Blackhorse Lane 
4. Back Lane was Rochel Street 
5. Balfe Lane was Pitt Street 
6. Belmont Avenue was Coldblow Lane 
7. Benburb Street was Barrack Street 
8. Bishop Street was Great Boater Lane 
9. Blackhall Place was The Gravel Walk 
10. Bow Lane was Elbow Lane 
11. Bow Street was Lough Buoy 
12. Brabazon Street was Cuckold's Row 
13. Bridgefoot Street was Dirty Lane 
14. Brookefield Avenue was Watery Lane 
15. Brookefield Road was Cutthroat Lane 
16. Camden Street was St. Kevin's Port 
17. Cathel Brugha Street was Gregg Lane 
18. Cathedral Lane was Cabbage Garden Lane 
19. Chancery Place was Mass Lane 
20. Christchurch Place was Skinners' Row 
21. Clonliffe Road was Fortick Road 
22. Collage Green was Hoggen Green 
23. Constitution Hill was Glasmunogue 
24. Dame Street was Tengmoutli Street 
25. Dean Street was Cross Poddle 
26. Digges Lane was Goat Alley 
27. Dorset Street was Drumcondra Lane 
28. Engine Alley was Indian Alley 
29. Essex Street was Orange Street and earlier it was Smock Alley 
30. Exchange Street Lower was The Blind Quay 
31. Exchequer Street was Chequer Street 
32. Foley Street was Montgomery Street and earlier it was World's End Lane 
33. Glover's Alley was Rapparee Alley 
34. Green Street was Abbey Green 
35. Haddington Road was Cottage Terrace 
36. Hammond Lane was Hangman's Lane 
37. Harrington Street was Whitworth Street 
38. High Street was Main Street 
39. Hill Street was Lower Temple Street 
40. Infirmary Road was Aberdeen Street 
41. Island Street was Dunghill Lane 
42. Lansdowne Road was Watery Lane 
43. Lincoln Lane was Pudding Lane 
44. Lincoln Place was Park Street and earlier it was St. Patrick's Well Lane 
45. Little Green Street was Bradogue Lane 
46. Little Ship Street was Pole Mill Street 
47. Lower Baggot Street was Gallows Road 
48. Lower Gardiner Street was The Old Rope Walk 
49. Mary's Lane was Broad Street 
50. Mercer Street was French Street 
51. Mespil Road was Gibbet Meadow 
52. North Brunswick Street was Channel Row 
53. North Lotts was Newfoundland 
54. O'Connell Street was Sackville Street 
55. Upper O'Connell Street was Drogheda Street 
56. Old Kilmainham was Murdering Lane 
57. Oliver Bond Street was Mullinahack 
58. Parnell Square was Rutland Square 
59. Parnell Street was Great Britain Street 
60. Pearse Street was Great Brunswick Street 
61. Pimlico was Donour Street 
62. Prussia Street was Cabragh Lane 
63. Railway Street was Upper Tyrone Street and earlier it was a Part of Mecklenburgh Street (see Waterford St.) 
64. Sackville Place was Tucker's Row 
65. Sean McDermott Street was Gloucster Street and earlier it was Great Martin's Lane 
66. Shelbourne Road was Artichoke Road 
67. St. Andrew's Street was Hog Hill & earlier it was Hoggen Hill 
68. St. Michael's Lane was Macgillamocholmog's Street 
69. St. Stephens's Green North was Beaux Walk
70. St. Stephen's Green South was Leeson's Walk 
71. St. Stephen's Green East was Monk's Walk 
72. St. Stephen's Green West was French Walk
73. Talbot Street was Cope Street North 
74. Townsend Street was Lazy Hill and earlier it was Lazar's Hill 
75. Usher's Lane was Dog And Duck Yard 
76. Waterford Street was Lower Tyrone Street and earlier it was Part of Mecklenburg Street (see Railway Street) 
77. Wellington Street was Paradise Row 
78. Wolfe Tone Street was Stafford Street

This is not a complete list of street name changes, but just be careful if you have an older map.

What do these road signs mean?

Over recent years I have started to notice road signs like these around Dublin. I have been fascinated to find out what the signs are pointing to, but it is hard to guess their meaning since the signs only contain an abstract shape in either black on a yellow background or visa-versa.

Sometimes the signs will appear on their own (like the first example), or else they will be a small addition to an existing sign with many directions as you can see in the example below.

Occasionally I have tried to follow the signs to see where they lead to, but always I have given up after several left/right turns that don't seem to be leading to any particular direction.

Can anyone take me out of my misery and tell me what the signs mean?

Are they a Dublin phenomenon or do they appear in other parts of Ireland? Can the y be found in other countries?

Where the streets have too many names

U2 had a big hit with a song named "Where the streets have no name", but in Ireland many streets have more than one name. Sometimes the change is minor, like when "Baggot Street Upper" becomes "Baggot Street Lower", but other times the streets have totally unconnected names. This is very confusing for visitors and locals alike.

One of the worst examples starts off in Rathmines, where you can travel 3 km along a straight road but officially be walking on 9 different street names:

1. The journey starts on "Rathmines Road Upper".
2. As you head north you will see that the road becomes "Rathmines Road Lower" which probably is no surprise.
3. Continue straight and as you pass over the canal and you will see that for a short time you are travelling on "Richmond Street South". If this was not confusing enough, after a short while you will come to a junction where you can either continue straight or turn right and in both cases you would still be on  "Richmond Street South".
4. Assuming you keep straight, the road will transform itself into "Camden Street Upper".
5. Unsurprisingly this road changes its name into "Camden Street Lower".
6. However, if you continue straight on the same road, you might be a little confused to find that the road transforms again into "Wexford Street".
7. Many Dubliners know "Wexford Street", but relatively few realize that if you continue walking straight along this street you will be on "Redmond's Hill". If you are looking for this piece of the road, don't be fooled by the name into thinking that there should be some slope in the road - this is a perfectly flat stretch of road.
8. If you are confused to find yourself on "Redmond's Hill", don't worry - it only lasts about 100 meters or so before transforming into "Aungier Street".
9. "Aungier Street" is reasonably long, but clearly some city planners decided that it was too long since it changes without warning into "South Great George's Street". Don't be fooled into thinking that walking north on "South Great George's Street" would bring you to "North Great George's Street" - that street is several km away in a different part of town. Instead the road comes to an abrupt end in a T-junction with "Dame Street" (needless to say "Dame Street" also has several names)..

Is it any wonder that tourists get confused when they ask someone what street they are walking along and they are told "Aungier Street" and then 5 minutes later they ask someone  else and they are assured that they are walking along "South Great George's Street" despite the fact that they have been walking straight all the time.

Much of FourSuqre's attraction comes from its mystery

FourSquare is clearly the leading location based social network. The reason seems to be that most people agree that it is the platform that provides most fun. Unfortunately for their competitors it is hard to define exactly why it provides most fun. Personally I think that much of the enjoyment comes from an element of mystery about how exactly the rewards are handed out.

If you have used FourSquare you will probably know that they award badges for various activity. Once you unlock a badge, they give you a page explaining exactly why you were awarded it. However, they don't tell you in advance exactly what you will have to do tho earn badges that you have not yet been awarded. It is not really hard to guess that for example the Newbie badge is earned for your first ever check-in and if you hover over the logo for an unearned badge they will give you a hint, but you still don't know the rules for sure.

For me, I know that FourSquare often gives me a pleasant surprise when I earn badges or points that I was not expecting. For example, this morning when I checked into my local Lidl I got a surprise to see that I earned 25 bonus points for being the anniversary of my first check-in. If the FourSquare team keep up the good work  I will probably keep using it for a feew more years.

You know you are definitely back from Holidays when you lose all of the Mayorships in Foursquare

Earlier this year I went on a holiday of a lifetime in South Africa. I was so thrilled with myself for being so far away from home that I regularly checked in with FourSuqare. As a result I was declared "Mayor" of a wide variety of locations.

After I arrived back in Ireland, the glowing feeling of well-being from the holiday faded fairly fast, but the FourSquare mayorships were surprisingly long lived. I was just notified yesterday of the fact that I was ousted as mayor of the beautiful Knysna Country House. I am still Mayor for Fancourt, Hotel in George - but I am not sure how much longer that will last and all of my Foursquare mayorships will ba back in Ireland.

Sometimes Computers get stuff very wrong

There is an old joke "To err is human, but to really mess things up you need a computer".

I don't run very often, but when I do I normally use the My Tracks application on my Android phone to track my progress. This allows me to keep a training record which is usually very accurate. However, the other day I went on a training run that was more or less following the route of the Streets of Galway race. I had to run a little bit extra to get to and from the race route so I reckoned I would have clocked up slightly more than 8km. Imagine my surprise when I looked at the route that my phone thought I took. Instead of running roughly 10km per hour on the streets of Galway, it thought I was swimming at over 100km  per hour around the Irish Sea!!!

View Galway in a larger map

Cross Posting from MyTracks to DailyMile

As I wrote before, I find that the My Tracks application from Google is a very useful and easy to use utility to use for tracking my running training. Howver, I have noticed that many people I know seemed to be using an application called DailyMile to post details of their exercise activity on Facebook.

This integration with Facebook seems to be great fun and it allows people to give and receive motivational messages, so I decided to register for DailyMile myself to see how it worked. When I started using it first I was surprised shocked to find that people are expected to manually enter details of the routes that they run. It struck me that there should be an application to automatically upload GPS traces to DailyMile, but when I asked a few friends nobody knew of one. However, my asking sparked a colleague Ben Hardill from IBM's Hursley lab to take on the challenge of building such an application. It only took him a few days to get it working and he describes his progress on his blog.

He has not yet officially released the application, but he asked me to be one of the Beta testers. It works brilliantly, with one limitation which means that you must use a regular DailyMile account rather than logging into DailyMile with your Facebook credentials. This bug is caused by a limitation in Daily Mile's implementation of OAuth rather than a limitation in Ben's code and in any case doesn't bother me, because I don't have any significant Daily Mile history to worry about abandoning

The existence of this application provoked me to go for a run this morning before work just so I had something to use to try out the application. I am glad to say that it worked great.

Starring on Google Street View

A few years ago my brother and I hired out a cruiser and spent a week cruising with our families on the Shannon. When we were passing through Carrick-on-Shannon with our hired cruiser we spotted one of the Google Street view cars in the vicinity. I made a mental note of where I was when I spotted the car and when Street View was initially launched in Ireland I tried without success to see us on the site. The important point to know is where were we when the car saw us, not where were we when we saw the car.

However, I was browsing randomly on the site the other night and I happened to spot us appearing clearly as you can see from the screenshot below. You can click here to see us live on the web, but it is normally quite hard to find us because if you move to the position either left or right of this exact position there is no boat in the river. It seems that google selects images from multiple passes through an area, and we only appear in one of the passes (if you look carefully you can also see someone taking a picture of the Google Street View car).

In all modesty I must say that we look very good, but it would be hard to recognise us if you didn't know exactly who was on the boat at the time (I was driving and am partly obscured from view). You might think that it is extravagant for a recently appointed mayor to be driving such a fancy cruiser, but I must admit that it was only rented from Emerald Star. Hopefully the local Bord Failte office will be sending us payments in reward for the great way we are advertising the amenities of the area.

How I became mayor of my local Gym

Since a General Election has just been called in Ireland, many people might be wondering how to achieve elected office. Those of you who follow my Twitter stream might have noticed my recent tweet "I just ousted @slkav as the mayor of Westpoint Health and Fitness Blanchardstown on @foursquare http://4sq.com/6LqwIq" and wondered how I achieved that.

This was actually achieved very easily compared to how difficult it would be to become a real mayor. I recently started to use a service called FourSquare which allows you to check-in to various locations to tell your friends where you are. Initially I was quite skeptical about the potential benefit of using such a service, but since it seems to be growing in popularity I said I would see what the fuss is about.

An obvious thing to worry about using a service like this is that you might not want people to know where you are at any particular time. However, this is not really an issue, since FourSquare only tracks my  location when I explicitly check-in to a location (typically by using an application on my phone). This is quite different from services like Google Latitude or Facebook Places which can sometimes be publishing your location without you being consciously aware of that.

Initially I did not use it much because I was not sure when I might want to publish my location but then I joined a local gym and decided that I ought to boast about that fact to my friends. In my first check-in, I did not realize that the Gym was already registered on Foursquare and so I accidentally registered it a second time. The next two times I visited the gym I check-in properly with FourSquare and hey presto I was declared to be the mayor (based upon the fact that I had checked-in more frequently than anyone else in the previous 60 days) and FourSquare automatically tweeted the good news on my behalf. I should point out that at the time I was the only person check-in to the gym on FourSquare, but the gym was packed so the most frequent person to check in on FourSquare is not really a good estimate for who is visiting the gym most often.

Will this service catch on? I think it probably will, because it combines a fun element. I saw that my predecessor as mayor of the gym tweeted "nooooooooooooooooooooo!" in reply to the news of me becoming mayor, so maybe FourSquare can encourage more visits to the gym as we battle for the mayorship.

Why I was wrong - Loc8 codes are a great idea

Ireland is pretty unusual for a developed country in that we have no system of national postcodes. Although the government have being discussing the introduction of postcode system for the last few years, but the discussion doesn't seem to be getting any closer to reaching a conclusion.

In the meantime an enterprising company from Cork have invented their own post code system called Loc8 and they are actively promoting its adoption as a de facto national standard. To quote from their new web site "Loc8 Codes are the first and only All-Ireland Digital Address Code which is a smarter form of postcode. You can now easily find an exact location anywhere on the island of Ireland".

I looked at their web site and was quite impressed by the very sensible system that they are proposing to algorithmically transform between latitude and longitude coordinates and a post code string which is easy to remember. However, my inner geek was disappointed with the lack of detail provided about how the transformation was done and the company seemed to have the attitude that since they provide a free and easy to use conversion utility on their web site they didn't need to tell people the details of how the conversion was done. I was further outraged when I clicked on the link to their terms of use document - although I didn't read it carefully I was surprised to see a lot of legal jargon setting out restrictions.

I recently wrote on my blog about how Loc8 codes were basically a good idea, but that their restrictions were unreasonable for any proposal that hoped to be adopted as an official government standard. One of the people behind the company responded to blog post pointing out that do not in fact place restrictions on the use of Loc8 codes. The restrictive terms are in fact merely restrictions on the use of the aerial images from the Ordinance Survey office that they use on their webs site (and these restrictions are outside their control anyway).

A closer reading of their legal documentation made it clear to me that I was wrong in my interpretation. I am happy to admit my error and publicly state that I have been converted into a fan of this proposal.

A post code system for Ireland

I read an article in yesterday's Irish Times which spoke about the post code system that they say will definitely be launched by the end of 2011. While I think that a system of post codes for Ireland would be a great idea, I am sceptical about the likelihood of it being launched this year. Part of my skepticism comes from the fact that there is no clear agreement on how the new post code system will work, but also I have heard such confident predictions about a post code system before. For example, this news item from RTÉ which was written in 2005 an confidently predicted that Irish postcodes would be in operation by 1st of January 2008.

The current proposal is that the post code system  will start with a number of letters identifying the nearest town or city. This proposal has generated a backlash from the Irish language supporters who are insisting that the initial letters in the post code should come from the Irish name for the town rather than the English name for the town - in many cases these would be the same but Dublin/Baile Átha Cliath is a high profile example where they differ. In addition, if the system was to be adopted I can easily envisage a situation whereby small towns could be campaigning to have their own initial letters rather than being lumped in with a rival town.As a result I think that any system based upon place names is doomed to failure and disagreements. Instead we should ensure that the post codes are based upon latitude/longitude coordinates. This is especially relevant in the modern world where SatNav systems are almost ubiquitous and all work of of lat/long coordinates. For example the LOC8 system being pushed by Garmin has the general right idea in that they have a simple algorithm that converts between lat/long coordinates and a more easy to remember alphanumeric post code.

The one big problem with the Loc8 system is the fact that they are treating the algorithm to convert between post codes and the coordinates as a trade secret. I think that the company behind the Loc8 system is very foolish to take this attitude because they would make more money from their technology if the government were to adopt it as the official post code system, but there is no way that the government could endorse a postcode system whose workings were kept secret. . As I mentioned the algorithm is quite simple and so it would be trivially easy to reverse engineer the algorithm given a few sample coordinate/postcode pairs and the details that they provide on their web site. However, my understanding is that the company behind the Loc8 system would sue anyone that published the details of their algorithm - they don't charge people a fee to convert, but their policy is that the only way to do the conversion is via their web site.

Finding your way around Dublin using public transport

I just discovered a brilliant site Hit the Road which allows you to find your way around Dublin by using a combination of different modes of public transport.

One of the things that makes getting around Dublin by public transport difficult is the fact that there are three totally independent public transport systems, Dublin Bus, Irish Rail and Luas each with their own web site which contains routes and schedules. However, if you use the Hit the Road web site, you can  simply enter where you want to go to and where you are starting from and it will automatically find the best combination of services to use. It will even give you an estimate of your overall travelling time including walking to and from the bus/train stops. If there are a few alternatives which are close to being optimal it will show each of them so that you can manually choose and it will include a helpful link to the schedule for each of the services it is recommending.

It is great to see private innovation helping solve real problems for the citizens of Dublin while we are still waiting many years for the long promised integrated ticketing system between the various services.

The Talbot Hotel relocates from Wexford to Leitrim

I am a big fan of Google maps and normally it is fairly accurate, but when it gets things wrong it can sometimes be wrong in spectacular ways. For example, I was recently browsing the Google Maps and looking at Carrick-on-Shannon in Leitrim. I was surpised to see the Talbot Hotel marked in beside the Quay because this is a well known Hotel in Wexcford over 280 km away. I am not sure who created the listing page, but it is quite detailed with lots of pictures and even almost hunded reviews. I feel sorry for the poor tourists who book into the Hotel based upon the good reviews and then find themselves over 3 hours driving away from the Hotel's real location when they come to check in.

Is it possible to call the Google Street View cameras back to take a nicer picture?

There was much excitement recently about the fact that Google Street View finally released their photos for Ireland. It was a few years since the photographs were taken and the delays were explained by the fact that there were concerns expressed by the privacy implications of people's pictures appearing and they needed to semi-automatically blur any faces accidentally captured.

Naturally I decided to have a look and see how my own house looks on Street View and although I don't think it looks too bad, I was a little disappointed to see that the hedge in the front garden was clearly overgrown. As a matter of fact the hedge in question has since been removed and I wondered if there were any way to possibly call back the Google Street View cars to take a new picture of my now tidier front garden?

For me it is not a big deal how my house looks to casual browsers, but I can imagine if a business premises had spent quite a considerable amount of money to renovate their premises they would not be  happy if people using Google Street View were still seeing the older un-renovated view. Perhaps there might even be a business opportunity for someone to go around taking professional photographs showing off a business premises at its best!

Navigating the new N3/M50 junction

The new M3/M50 junction is a truly impressive feat of engineering. However, it is very complicated to navigate through it. As you approach heading towards town along the N3 there are pretty clear signs showing you how to navigate straight on into town or to take the M50 North or South. Unfortunately the signs are not as clear for local traffic which wants to get off the Motorways and into either Castleknock or Blanchardstown Village. The traffic can be quite heavy so if you are not in the correct lane you might not be able to change. Therefore I thought it might be useful to write up instructions for both of these options.

None of the major commercial on-line maps have yet been updated to reflect the new junction layout, so Open Street Map is the only one with accurate information. You can see the picture of the junction below (click here to see a live zoomable version)

If you want to get to Blanchardstown Village you need to follow these steps:

1. Stay in the leftmost lane as you approach the junction (it will be marked for Blanchardstown Village and some of the signs also have Blanchardsown Hospital poorly crossed out).
2. As you enter the ramp left you will see traffic lights and a left turn for Blanchardstown Hospital, but you keep going straight. At the time of writing the traffic lights are not in operation and the road to the Hospital is blocked off, but the road looks nearly ready to open so when you go there it may well be in use.
3. The Ramp road will swing right and bring you across the main line of traffic. Immediately after you pass Total Fitness on your left you will come to a T-junction with traffic lights.
4. Turn right at the lights and about 50 meters later you will come to another set of traffic lights where you need to turn left.
5. After this turn you just keep going straight and you will come to Blanchardstown Village.

If you want to get to Castleknock village you will need to follow even more complex instructions although you initially start out the same:

1. Stay in the leftmost lane as you approach the junction (it will be marked for Blanchardstown Village and some of the signs also have Blanchardsown Hospital poorly crossed out).
2. As you enter the ramp left you will see traffic lights and a left turn for Blanchardstown Hospital, but you keep going straight. At the time of writing the traffic lights are not in operation and the road to the Hospital is blocked off, but the road looks nearly ready to open so when you go there it may well be in use.
3. The Ramp road will swing right and bring you across the main line of traffic. Immediately after you pass Total Fitness on your left you will come to a T-junction with traffic lights.
4. Turn left at the lights and about 50 meters later you will come onto the remains of the old roundabout. 
5. You don't get off at the first exit, but instead you get off at the second exit (which has traffic lights).
6. Immediately after you exit the roundabout the road divides and you will need to keep to the left fork (it is signed for Castleknock Village, but not very prominently)
7. This road will bring you under three roads and then will end at a T-Junction with traffic lights
8. At the junction turn right onto the Dunsink Road.
9. After about 20 meters you will come to a major traffic light controlled junction with the N3.
10. You go straight through this junction and you will be on Auburn Avenue which will bring you into Castleknock Village (you may decide to stop off in Myo's pub for a drink to steady your nerves at this stage).

This picture illustrates the journey from step 3 onwards.

Although the junction is now much more tricky I am not really complaining. It was straight forward to navigate either of these options before the upgrade - in both cases you simply took the third exit of the clearly marked roundabout. However, during peak rush hour you would need to queue for anywhere from 20 minutes to 1.5 hours to get through, so the complexity of the new junction is well worth it in terms of saved time.

Cycling trip to Wicklow

It was a beautiful sunny day last Saturday. I had to go down to Wicklow anyway so I decided to take my bike with me and see how I would get on cycling in the Wicklow mountains. I certainly wasn't the only person with the same idea and I met nearly more cyclists than motorists on the roads. I had a most enjoyable wandering around the area trying to avoid the worst climbs although there are no really flat roads in Wicklow (see the map of my route above or click here to see details of where I went).

At the end of the day I had clocked up 50km and was pleasantly tired.

How exact do you need to be when specifying longitude and latitude

If you want to follow the advice of my previous blog post and advertise the position of your home or business via latitude and longitude coordinates, you might wonder how exact you need to be with your measurements. Obviously if you are more precise when you measure the position you lessen the chance that your friends will call to your neighbour's house instead of yours, but on the other hand a long number is harder to remember than a short one.

The level of precision needed depends slightly upon how big is the place is that you are advertising and where exactly on the globe you are, but the short answer is that 4 decimal places are often enough and 5 decimal places is definitely accurate enough.

If you want to learn how to accurately convert lat/long cooridnates into distances you should read this web page (be warned the maths gets complicated) but a rough rule of thumb is that if you need to move one meter north or south to increment the fifth decimal place of your latitude i.e. 0.00001 degrees north is one meter away from the equator. The same rule of thumb can be used when conversing between longitude and distance when you are at the equator, but as you move away from the equator there is a decrease in the distance represented by a given number of degrees. For example, in Ireland if you move 0.00001 degrees east or west this is a distance of only 60cm on the ground. It is hard to imagine a situation where you would need to specify your location with greater accuracy than this and in any case most consumer GPS devices would not even be this accurate.

If you look at the page listing IBM locations in Ireland you will see that some of the GPS co-ordinates are given to an accuracy of 6 decimal places which specifies the location of the facility to a precision of 10cm, which is obviously much to much detail.

A smarter way to advertise the Location of your business

The North Western part of Dublin where I live is changing rapidly. A large number of businesses are constantly opening up (and closing down). In addition new roads are constantly being built and as a result it is very difficult for people to find their way. People running businesses are concerned to see that their business can easily be found by potential customers. As a result businesses will often spend money erecting signs like the one shown in this picture directing people to their business. Since many people now have SatNav systems it would be much better if businesses would merely publicise their latitude and longitude.

For example, this sign is quite a distance from the Hotel to which it is directing you and because of the way it is positioned is  not clear whether it is directing you straight through the roundabout or to turn left (possibly it was knocked off course by the wind). In fact you could get to the hotel in question quite easily by taking either direction. If you look for directions from Yahoo maps, you will be directed straight ahead at this junction, but there are 11 steps in the directions from Yahoo and when I travelled along the route recently only 3 of these had signs directing you which turn to take. So someone whose only clue was the signs erected by the hotel would get hopelessly lost.

The hotel web site has a page giving detailed directions how to get there. They also state the their "Go Code" is "L2H GJFK". After much searching on the web I found that this code comes from a company who are trying to promote their own scheme of post codes for Ireland. The company has a secret formula for converting between Go Code and Lat/Long coordinates (the only way to convert between them is by using the companies web site). It would be much simpler if the Hotel advertised that they are at latitude 53.366 and longitude -6.389 (I found this out using this simple tool I wrote a while ago - but there are many other ways to do this).

IBM follows this strategy for the page listing the IBM locations in Ireland. It is trivially easy for anyone to enter the latitude/longitude coordinates of the site you want to visit into any brand of SatNav and/or any of the popular mapping tools. The measurement of position by latitude and longitude are one of the few systems that work anywhere in the world. This is especially useful in countries like Ireland who have no widely accepted standards for how addresses should be written.

Open Street Map boldly goes where other mapping providers don't dare to tread

One of the main issues when using a Satellite Navigation (SatNav) system is ensuring that you have accurate and up to date maps for the area where you are travelling. Some areas (e.g. Dublin) can change quite rapidly as new roads are constructed and so maps that were produced only a few years ago can be inaccurate and misleading. Professionally produced maps can be expensive - updating the maps on your SatNav can cost almost as much as the cost of buying a new SatNav unit. Luckily it is possible to get free maps which have been produced by the local community (who know the area better than anybody). For example, OpenStreetMap is the best know community produced map which makes all of its data available on a creative commons license. In many instances the community produced maps can be superior to the expensive ones produced by the professionals.

Forexample, the IBM campus where I work is technically private property, but since it is a large complex site it really ought to be mapped (e.g. it contains the first two stops on the number 38 bus service). The Yahoo Maps service, normally provide accurate mapping data for Ireland. However, if you look at their map for the area it is clear the mapping company who produced their maps stopped at the entrance to the campus and turned around.


In contrast, if you look at the OpenStreetMap map for the same area you will see that it has excellent detail of all of the internal roads within the campus. Each of the buildings are identified and it even includes the walking path around the edge of the campus where many people go for a walk through the trees at lunchtime. Someone has even gone to the trouble of recording the location of the recycling facility.


This is a clear case where expensive does not imply better.