Navigating around maps on websites. A guide for local authorities (and others)

Map showing gritting routes

I was supposed to be sorting out the garage. In a desperate act of prevarication, I checked Twitter. Sure enough Dan Slee had posed a gnomic question to the world.

I’m not totally sure what the argument was or who was arguing. But there are some issues that are worth exploring. Though this post has local authorities in mind most of these issues actually apply to anyone using online maps.

  1. Why put maps on your website?

Maps can be useful for displaying (and allowing people to report) lots of information. If the information has a spatial component then maps can be a very helpful way of understanding that information. So if this is information about a specific location a map can help people understand where that location is relative to their location or a third location.

Here’s a map of the routes that are gritted in Herefordshire [disclosure I was responsible for creating this map in the first place though I no longer work for the council].

Maps aren’t suitable for all users or in all circumstances. People who can’t see the screen, who have difficulty processing this sort of abstract information or are unfamiliar with using maps need other ways of navigating this sort of data.

2) GIS and the printing of maps

Usually (though not always) when people sit down to plan gritting routes they draw them on an electronic map. Specialist Geographical Information Systems make this sort of thing easy and make it simple to change routes (when a new school is built for example). And, in principle, this information can be shared with other departments (the bin lorries like to know which routes are going to be gritted for example).

In a local authority, inevitably, these routes will be drawn on electronic versions of Ordnance Survey maps. It’s easy to forget that the Ordnance Survey dataset is amongst the best quality mapping that any country has. Under the Public Sector Mapping Agreement local authorities (and town and parish councils) get to use the OS data for their patch under a licence.

The simplest way to get the gritting routes from the GIS software onto the website is to output a screenshot as a PDF (or a JPEG). Easy but not very useful. PDFs are unusable for almost all cases (reading long reports offline on a mobile phone would be one exception). Either format can’t be zoomed and so, to cover a county like Herefordshire, a large number of PDFs or JPEGs would have to be shoved out.

3) Bring on the Slippy Map

A much more useful concept is to use the awesome power of the Internet to display the mapped data in an interactive way. You’re probably most familiar with this from Google Maps. If the bit you are interested in lies to the right of the map you’re viewing you just reach with your cursor (or finger these days) and drag the map to the right.

Already this is a much better way to display gritting routes. As technology should this, now familiar, approach actually relies on a series of clever and complex interactions.

This is a post aimed at a reasonably general audience so I’ll risk the ire of GIS geeks with a simple description.

In order to get the gritting routes on a slippy map on a council website, several things need to be delivered.

The background mapping has to be available in a dynamic format, so that as you drag the map to the right, a service sends the maps covering the new area. These are just images (called tiles) though they have to be delivered so they can be shown at the right scale and in the right place.

The lines for the gritting routes have to be delivered in a similar way. They form a separate layer and are drawn on top of the background mapping. They also have to be delivered in so they can be shown at the right scale and position.

Then you need a tonne of code in your webpage that will go and get the background maps and the routes and display them, and handle the interaction with the user.

4) Give it to Google

One of the very attractive things about the Google Maps service is that it makes it really easy to do all of the things described above. You can draw your gritting routes in its service, grab a simple embed code and bosh an interactive slippy map.

Here’s Herefordshire Council using Google Maps to display car park locations [disclosure I totally failed to stop using google for this service in my time at the council].

So that’s it then?

Well no. Back in step two we saw that the gritting routes were drawn on top of Ordnance Survey data. The licence the council uses the data under means they can’t give that information (which in this case is incredibly accurate information about where roads are) to Google.

5) So are we stuck?

We most certainly are not. There are a huge range of solutions open and closed source for delivering mapping on council sites. And under the PSMA the council is perfectly able to publish maps.

6) Maps are good. Data is better.

Just supposing you want to drive from Hereford to Worcester. You want to make sure you followed gritted routes. You need to visit two websites: Herefordshire Council for the Herefordshire part of your journey and Worcestershire County Council for the Worcestershire part.

It’s not a brilliant user experience. There is, of course, an alternative. Just supposing you want to drive from West Bromwich to Edgbaston. You could visit the relevant websites or you could visit this map from Mappa Mercia. Which displays all of the gritting routes across the West Midlands conurbation.

Brilliant. Why don’t they include gritting routes further afield? Well they would like to but they encounter the licensing problem. Mappa Mercia is an OpenStreetMap project and OpenStreetMap can’t use data with restrictive licenses.

There are many, many reasons why local authorities might want to support OpenStreetMap but they’ll have to wait for another post.

7) Data is rubbish. Open data is resource.

Imagine a world where the gritting routes the council used were derived in an open way. Perhaps by putting GPS loggers (or as I like to call them “phones”) in the cab of the gritters.

Those gritting routes wouldn’t be restricted by the Ordnance Survey license. They could be used to create Google Maps, OpenStreetMaps (or used in Bing or ESRI or a whole host of other services). WHo knows what use people might make of them.

The local authority would carry on using them against OS data in its back office.

The open and the un-open

This blog post is not complaining about OS licensing restrictions (not least because the OS is, in fact, opening ever more of its data. It’s an issue. It can be worked round. Like many situations where data can be open or non-open there is an imbalance. The way the local authority chooses to collect (and publish – I haven’t really gone into that) its data has real impacts on the use of the data by third parties.

This post will change nothing

To some of us, these downstream impacts are clear and urgent. But to most people it’s abstruse and abstract. We need to find ways to encourage people across public services (and other sectors too) to understand some of these issues. This blog post is probably not going to achieve that. But it has got me out of tidying up the garage.

(Image credits: Screengrab from Mappa Mercia site (c) OpenStreetMap contributors)


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