From the start we realised we needed to make the National Broadband Map as accessible as possible. Besides being a mandated requirement for core government websites under the New Zealand Government Web Standards, addressing accessibility helps ensure that website and application design reflect global good practice and provide improved usability for everyone. Taking account of accessibility right at the outset of the project, in fact in our RFP, lead to a more rounded and functional application. We were aware that the extra complexities of a dynamic and very visually-based application meant we couldn’t address accessibility at another point of project but the beginning.
Accessibility is sometimes thought to benefit only to those those with disabilities. In fact, accessibility is really about making information and data easily available to everyone, regardless of who they are and how they access the content. We wanted to make the National Broadband Map accessible to as many people as possible. The nature of the world wide web means we can’t choose our audience, they choose us. We can’t predict or dictate how people will access the application.
Keeping content and design separate
Content is what you want people to see, read and do. Design is how you want that content to be rendered on a screen. There’s art and science to that latter bit.
The Internet is not always viewed through standard, javascript- and flash-enabled web browsers and designing for these alone is not enough. Search robots don’t use browsers, sight-impaired people may use screen readers or tactile braille machines, text-only browsers are still in use, and sometimes images are turned off and plugins are absent or deactivated.
Because of this, we used stylesheets to separate content and design. This included avoiding embedded font tags (the content shouldn’t carry the font colour) and using the smooth semantic flow of correct heading levels.
There is no need for content to also include information on what colour and font text is, as this is not something you are trying to communicate. You might want to communicate the importance of a heading (e.g. ‘Heading 1′, Heading 2′) but its colour and font don’t improve the quality of the content.
Access Keys
Because not everyone uses a mouse, we added access keys to let users navigate via their keyboard.
Accessible Demand Data Presentation
Maps are visual and making map data accessible might not seem a simple task. In reality it was quite straight forward. We just took the data we were displaying on the map and presented it in a tabular format (properly coded for assistive technologies). The data was already there - we just presented it in different way.
Tables
We used tables, but we used them for their intended purpose - to display tabular data, not to lay out the page. As the name suggests, tables are the best way to display tabular data. We’ve made sure the tables are well formatted, with table summaries explicitly describing the table content, and clearly identifed table header rows for easy use by screenreaders.
Micro formats
We’ve used microformats for our data. Microformats let data be extracted from a web page (in our case the tables displaying tabular data) for use by other applications. An example is the ability to add contact data to a contact management program via the hCard microformat. We’ve also included hidden microformatted data in our tables describing geographic positions using the GEO specification.
The APIs
The National Broadband Map is a data rich application. While we render the data in a geospatial format, we recognise it could and should be used in any number of other ways, and so we made it available via the database APIs (application programming interfaces). These APIs allow the data to be readable by people and software, and to be analysed and communicated by many methods.
Clustering
We’ve got around 12,000 demand points at present and this will only get larger. Displaying this number of points on one map presented computing issues, and threatened to overwhelm the application graphically with a great mess of thousands of icons. In addressing this we use a combination of server-side and client-side technologies to aggregate the data and display them as clusters. The size of the icon gives an indication of the number of demand points in the cluster and is also relative to the number of icons in the screen area being viewed. We give the top third the largest icon and the bottom third the smallest. When we view all New Zealand, the large icons contain hundreds of demand points. As you zoom in, individual demand points can be viewed. Aggregated and specific data can be displayed using the same interface.
There are some good guidelines on accessibility at the e-government Web Standards Wiki http://webstandards.govt.nz.
The National Broadband Map is beta at http://broadbandmap.govt.nz.
