Road Network Operations
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Emergency Response

Most emergencies are characterised as “short” or “no-warning” incidents or events, such as sudden major storms or other severe weather events, airline or train crashes, earthquakes, flash floods or terrorist threats. The less frequent, but usually more devastating events are “with-warning” emergencies, such as a hurricane, tsunami, tidal wave, flash flood, major river flood or spreading wild fire. The response to these different levels of emergency can be very different.

Having days to prepare for something like a hurricane or flood allows agencies to alert the public in a timely way, to stockpile or reposition resources, to muster additional resources and ultimately, prepare for evacuation. Emergency managers and responders can be more proactive in their responses.

When the warning is short, or non-existent, the response is almost entirely reactive. This is why Emergency Management protocols require extensive planning, preparation and training. Transport agencies are advised to be more involved in development of Emergency Operations Plans. (See Emergency Plans)

There are two aspects of primary concern:

  • the effect on the emergency on the transport network
  • the role of the transport system in the response

When transport is not directly compromised

When the transport system itself in not materially impacted – by a pandemic for example – the transport network becomes the focus of responding agencies. Roadways, public transport, trains, boats, ships and airplanes become the means of avoiding or evacuating from the emergency.

For traffic operations, transport managers can take the following actions to assist emergency managers:

  • travel information systems – use VMS, PDMS, HAR, social media and other motorist information systems to inform the public of routing, emergency shelter locations and evacuation routes. In emergencies, media feeds (including social media) will come from the incident command post – TCCs should continue to provide traffic information to the media if the emergency managers do not
  • CCTV video images – feed video images from CCTV to the EOC and intelligence Fusion Centre (FC), if there is one
  • Mobile Safety Service Patrols – use patrols to help control traffic and assist public safety agencies as needed

When transport is compromised

When the transport network is directly impacted by the emergency it will be less effective in serving the emergency and its managers. This is where emergency pre-planning and preparation within the transport agency are so important.

Emergency response – USA


In the USA, the Florida DOT and several coastal urban areas in this hurricane-prone state, stockpile traffic signals and generators in order to be able to replace damaged signals and to control restored signals in the absence of commercial power. Portable Dynamic Message Signs (PDMS) can temporarily replace damaged VMSs. Temporary Highway Advisory Radio units can be used for a similar purpose – but need to be supplemented by fixed signage that informs travellers of the HAR station frequency.

Effective communications is essential between Traffic Control Centres, Emergency Operations Centres and other centres where data and information about the emergency is collated (“Fusion Centres”) but not always fully achieved. Often it is because of differences in the jurisdictions of different transport agencies, emergency mangers and security people. Law Enforcement Dispatch Centres and Emergency Call Centres (999) can be included in the mix. In some regions this problem is exacerbated by the lack of open, non-proprietary communications protocols.

All can be connected by telephone and the Internet but co-location or direct electronic linkages for data, camera images and information sharing is more effective.


Extreme emergencies might require evacuation of residents and visitors, sometimes from large areas. Because of their extreme nature, a region can never be fully prepared to meet all of the challenges – both physical and institutional – that arise. From a traffic perspective, any evacuation is going to severely threaten the capacity of the transport network to handle it. Most of the actions that agencies can take to mitigate the negative impact of an evacuation and help keep traffic flowing require changes in the physical infrastructure or the use of mass-passenger modes.

Public transport

Public transport (transit), school buses and trains can be used to transport evacuees, particularly those that are mobility-challenged – such as patients in hospitals and other health-care facilities, students, the homeless and prisoners. These arrangements take time to organise and carry out, and require good inter-agency cooperation. ITS can assist to a some extent – for instance by giving bus drivers the same traveller information that other vehicle occupants receive.

Reverse flow lanes

In urban areas, entire city streets can be shifted to one-way operation to accommodate large numbers of vehicles escaping harm’s way. These require large numbers of police or military officials to control traffic. ITS does not have a significant role here, other than to minimise the conflicting guidance that traffic signals might indicate (such as green displays in the “wrong" direction).

Contra-flow lanes

These can be deployed effectively to use the inbound capacity for outbound evacuating traffic. Emergency contra-flow lanes are often in rural areas. ITS can contribute through VMSs to reinforce contra-flow guidance, CCTV to monitor the traffic - and the provision of travel information to inform travellers. Most public information will be generated by the incident command centre. The increasing use of probe vehicles can give transport and emergency managers data on journey times.

In a few instances, devices such as motorway ramp-closure gates can be deployed for use in contra-flow operations. Normally motorway entrance ramps have to be closed to traffic.

Hurricane Rita, Texas 2005

The photograph shows a contraflow operation in Houston, Texas before Hurricane Rita in 2005. Contraflow requires a great deal of advanced planning, physical preparation (such as the cross-over lanes), large teams of officials for implementation, and time to deploy and later restore to normal. A number of USA states on the Gulf and Southeast Atlantic coasts - as far north as Baltimore – have Contraflow Plans, but most regard the measure as a last resort.

 Courtesy Texas DOT.


Security threats are not very different to natural emergencies – except that they can have a broader range of impacts, such as cyber/Information Technology (IT) attacks, Chemical, Biological, Radiological, Nuclear and Explosive (CBRNE) threats and other terrorist actions. (See Network Security)

Much of the advice for emergency response applies to security threats – particularly in respect of threats to the transport network (for example the 1995 sarin gas attack on the subway in Tokyo in Japan and the 2004 train bombing in Madrid in Spain). The role of the transport network to respond to the threat is relevant – for instance, the closure of access to Manhattan Island in New York following the 9/11 attack on the World Trade Centre’s Twin Towers or when suicide bombers struck in Central London in 2005.

This supports the proposition for linking together Traffic Control Centres, Emergency Operations Centres and Information Fusion Centres. Emergency and security responders need to know the status of routes to and from the threatened area – both for responders and rescue teams.

Advice to Practitioners

A challenge to emergency managers is to avoid unnecessary evacuations. Following Hurricane Rita in Texas, the regional TCC’s (TranStar) spokeswoman, Dinah Martinez, said at a town hall meeting “During the disastrous Hurricane Rita exodus, part of the problem was that for every five people who evacuated, four of them probably didn’t need to." Traffic and travel information systems can be used as a tool to discourage people from leaving unnecessarily.

The opposite of evacuations is the confinement of people within an area – for example to contain a potential pandemic. In this case CCTV can show where vehicles are travelling when they should not be – and travel information can augment public safety notices.

Reference sources

Wallace, C.E., A. Boyd, Jason Sergent, A. Singleton and S. Lockwood. A Guide to Emergency Response Planning at State Transportation Agencies NCHRP Report 525 Surface Transportation Security, Volume 16, Transportation Research Board, Washington D.C. 2010. (Available for download at: