Transport for London (TfL) knows its online presence is vital for both customers and employees alike. The external site regularly gets 2 million visitors each month; the intranet, meanwhile, serves 19,000 employees, with up to a third using the site at any one time.

But when faced with a major incident – as happened on 7 July 2005, when London became the target for terrorist attacks – TfL brought the management of the external and internal sites together, ensuring that it could provide consistent and accurate information to anyone needing it.

At 10am on 7 July 2005 the first indications of a serious disruption to the service became apparent. Immediately, managers knew that they had to ensure that consistent information was relayed to all users: "We had to be careful, because rumours circulate very quickly," says Caroline Little, director of Internet services and head of new media at TfL.

As the traffic started flooding towards the website – at its peak the TfL homepage was getting 77,000 simultaneous hits, an unprecedented volume – the site was stripped of all marketing messages, ensuring faster rendering of pages. It also began mirroring content to Akamai Technologies' worldwide network of servers, to spread the load and ensure the TfL site was available.

The combination of robust action plans and good communication helped TfL maintain its online presence throughout the day. But Little says the episode has also highlighted future development needs. "It's not about finishing [the day] and saying 'we've coped'."