Cell Broadcast as an Emergency Alert Platform in the UK

The ongoing pandemic health emergency has resulted in Governments taking action to contact citizens directly with key messages to their mobile phones. Approaches to mass alerting to citizens have been via SMS, and in countries with the capability, Cell Broadcast (CB).

This blog explores what a CB-based public warning system looks like, summarises the Environment Agency’s Flood Warning Service contributions to the mass alerting conversation, outlines the key features of a ‘good’ public warning system, and offers some iteration points to consider for future messages being sent out during national emergencies.

What is a Cell Broadcast-based public warning system?

SMS or text message is commonplace whereas Cell Broadcast (CB) is only used in countries which have set up the service. CB appears like a text message but it’s effectively an alert that is broadcast from a mobile mast. This could be one mast or every mobile mast in the country. Like a radio broadcast it can be left ‘playing’ whether that’s 5 minutes or 5 hours — anyone in the area, or travelling through will receive the message, even where their signal is poor.

CB is a service that operates without users needing to subscribe or needing to know any personal information such as a users location or phone number. It is also not subject to network congestion and can reach millions of people instantly so they can receive vital information in a timely manner.

CB messages appear on mobile phone screens, and depending on the handset’s settings, it may also vibrate or make a specific, very loud alert sound which is a reserved tone only for this type of broadcast. Some phones can also read out the message or do other things to attract attention. This is a video from our lab test of Cell Broadcast; in it, the contrast between this and receiving a text message is stark.

Countries with Cell Broadcast alerting capabilities include the United States, Netherlands, Canada, New Zealand, South Korea and Japan, amongst others. In the US, Cell Broadcast is known as Wireless Emergency Alerts (WEA).

The Environment Agency believes Cell Broadcasting is well placed to reach those at highest risk during flood events — those travelling, driving through flood water and visitors or tourists who may not be aware of a flood hazard and are unlikely to be registered to any warning service.

What can the Flood Warning Service contribute to the Emergency Alerting conversation?

On the 24–25 of March 2020, the UK Government asked mobile operators to send out text messages to all citizens relating to the latest Coronavirus rules in force. Whereas this is the first time the mobile network sends out an emergency SMS on behalf of the Government in response to a national crisis, this is not the first time the Government has sent out emergency messages to the general public as end-users. The text is reproduced right.

One of the most frequent users of direct alerting in the UK is the Environment Agency’s Flood Warning Service.

The Flood Warning Service (FWS) has been in operation since 1996 and the Agency is experienced in drafting, creating, and sending emergency messages to the public. In the last ten months, FWS has issued 2,626,430 SMS messages to people at flood risk.

Running this tailored service has provided our teams with precious insights into how to best alert users at risk, as a Category 1 responder and having regimented incremental procedures to respond to different types of risk severity, urgency and certainty.

This expertise in the field of emergency alerting has meant that the Environment Agency has been assisting Cabinet Office with the newest trials of Cell Broadcast in England.

The Environment Agency’s (EA) role in Cell Broadcast trials is multifold. The EA is laying the foundations for a Cell Broadcast-led emergency system, testing the technology in partnership with the Mobile Network Operators, and running research simulation to validate the behavioural, affective, and emotive reaction of people who would be receiving an emergency alert.

This work picks up from the Cabinet Office trials of 2012–3. We have recently published our findings from private trials simulation, and are keen to share this learning with colleagues in public services, as well as the interested public. The study ran a technology simulation with 96 users, where we tested people’s immediate reactions to receiving this emergency message, explored their thoughts, feelings, emotions and action-based reflections on the matter. We also collected new evidence as to what is the ‘right’ content for people to have in an emergency message, and what risk thresholds would justify receiving an alert.

The major findings so far include:

• Emergency warning text to be action-focused, tailored, and easy to understand in a high-stress scenario
• Information not to be presented ‘as a wall of text’, but in a readable, broken up format (such as bullet points)Sensory response to novel handset behaviour is unnerving, but triggers attention and encourages action
• Users value combined severity and urgency over certainty
• Essential information should not be an offset journey (via URLs or call centres), but self-contained in the text
• Ways of expressing location and affected areas to be re-thought to be more understandable to all user segments
• Follow-up messages as important as first warning
• Pushing supporting information on parallel channels (radio, social media, etc) a crucial part of user validation post message receipt
• Undivided support for a robust emergency alerting platform to be implemented in England

As well as technology simulations, we are collecting people’s opinions via a public survey.

One of our public surveys is still open (please contribute to the conversation there too). At 1738 responses and counting, some key points which support the implementation of CB over SMS based approaches are:

People generally sleep with phones in their room, but do not receive and/or check their texts until the morning. Cell broadcast would be able to alert the user immediately at night.

From the graphs above, of our sample, 92% of people sleep with their handset in the same room as them. Of that, 89% of users would not check their texts until the morning if received during sleep hours. This work gives us some key insights into the different modes people switch their phone into at night — 24% is silent for texts and other notifications, 32% is completely silent, 5% switch off data overnight, and only 24% leave it on a normal setting. Other options from users include switching to airplane mode, disconnecting Wi-Fi, and other interesting combinations. Cell broadcast is a safe medium through which people could be alerted during sleep hours as some handsets will alert at full volume and some can override system settings. This is even more so effective during daytime hours.

We also found that people can suffer from alert fatigue. People are used to their phone dinging for a number of notifications, and it could be said that SMS messages have lost priority in the notification food-chain, with texts being associated with spam and unsolicited promotional material. This affects their ability and interest to react promptly to the message content.

The breakdown below offers an overview of the notifications received during a normal day by our users.

The urgent nature of CB messages overrides the notifications to which people have become accustomed to — with the understanding that this technology is used wisely, in genuine emergencies, and in a tailored way.

Besides flood, people are keen to see these emergency alerts for a number of other public emergencies. These were the preferences:

Overall, there is positive support from people for the implementation of a Cell Broadcast-based emergency alerting system:

What are the key features of a ‘good’ public warning system?

The Flood Warning Service continues to support the research, trial, and development of this technology. We believe the following four points are the foundations on which any Government mass alerting system should be built.

Our four priorities are:

1) An alerting solution should be shared and reusable across all of Government so as to warn for relevant hazards and threats.

2) Emergency Alerting should be available at low cost to authorities with Cell Broadcasting being comparatively lower cost than equivalent mass alerting systems.

3) A good emergency system is based on common standards, such as the Common Alerting Protocol (CAP), an international standard of exchanging emergency messages already in use, which has enabled our partnership with Google Public Alerts.

4) The overall proof of a good warning system is that it is based around its users. Digital services in Government are well placed to offer this, as they are benchmarked to the international standards set by the Government Digital Service (GDS) which encourages building user-centric solutions supported by continuous user research. This approach distinguishes us from other countries where warning systems have been developed, rolled out without first understanding the landscape of the complex user needs underpinning it.

The four points are distilled in the infographic below:

How can the GOV.UK text message be iterated?

This was the first time the UK Government issued a mass alert in response to a public health emergency. It happened in a short space of time, and has been overall a successful and productive initiative. It also surfaced some key learning points when mass alerting citizens.

For the recipients of the messages there has been a significant difference in time of receipt across the country. According to the BBC, network O2 has sent out the messages in batches as to avoid mobile network congestion.

Because of the batched, sequential approach, some people received the text in the morning, some in the evening, and the following day (25 March). This has potential to cause confusion in households where one member receives it before another — it creates the impression that the one receiving it first is more at risk. Some people received it twice, others none at all, and others’ was blocked by their phones spam filter.

In New Zealand, with a Cell Broadcast approach, the experience has been different. As messages are broadcast directly from the phone mast cells, this means receipt is instant (within around 5 seconds of being issued) to all handsets regardless of the mobile operator.

Message content in the government text message is concise and explicit. It reiterates the key messages we have heard on TV. It’s a very good start. There is also space for iteration on this: whereas those in receipt of the message were redirected to the GOV.UK pages. Best practice advises to keep the critical information in the same message, and only linking out for ‘further’ information or validation.

These points have been quickly noticed and discussed on Twitter as the ‘immediate’ echo chamber of national initiatives. Amongst the points in the public sphere, and as collected by some impromptu user research, the message sender is also a point of potential confusion.‘UK_Gov’ has in some cases been misinterpreted as being a scam sender. Soon after the national text was being sent out, similar texts were being recreated by scammers, redirecting to GOV.UK style pages asking for postcode and credit card details.

You can join in the Emergency Alert conversation, fill in our survey, or share your experiences, observations, and concerns. You can also find us on gov.uk/cellbroadcasttrials, or have a look at our Flood Information Service.

You can contact us on: Mobile-Alerting@environment-agency.gov.uk

Join in the Twitter conversation on: @Sissi_Grant @FloodDigitalEA @CellBroadcast