The chaos theory

While local authorities have consistent winter maintenance plans in place, the seasons inadvertently cause problems which are impossible to foresee or predict. Extreme weather can create dangerous road conditions at any time of the year, resulting in collisions and other accidents. While winter maintenance vehicles, the de-icing of roads and road gritters all ensure highway authorities are as prepared as possible for the winter months, emergencies will still cause havoc on the highway network at some point. Contingency plans, risk assessments and emergency response teams are the only sure-fire way to prepare for any future problems.

In addition to routine winter maintenance, highway authorities may also have to deal with traffic accidents caused by adverse weather and road conditions, flooding emergencies, the removal of debris and obstructions, and failures in the highway such as power cuts and damage to the road structure.

However, one thing is certain; no two emergencies are ever the same. Many factors affect the way an incident should be handled including its location, the current weather conditions, time of day and year, and the characteristics of the emergency. This can include dealing with broken down vehicles, clearing debris from the highway such as fallen trees, dealing with spillages and fires, and safeguarding unlit vehicles.

Facts and stats

Did you know that in one winter season:

• The number of accidents caused by wet road conditions increases by 267 percent

• There are 6,393 more accidents involving cars in winter than there are during the summer months

• Drivers are five times more likely to skid on snow or icy road conditions than they are on dry roads

Source:  Department of Transport (road accident statistics)

All in a day's work

A typical HTMA member company will be fully equipped and prepared to deal with weather emergencies, such as heavy snowfall, severe flooding or trees blown down due to gale force winds. Although severe weather warnings from the Met Office can help them prepare for such emergencies, some potential problems are impossible to predict. 

The most treacherous form of ice - and responsible for the large majority of road collisions - is black ice. Black ice is caused by the rapid lowering of surface temperatures by winds chilling the road surface. It is a thin coating of transparent glazed ice, allowing the black road surface to be seen through it. Not only is it extremely slick compared to other forms of roadway ice, it also has the appearance of a 'wet pavement' making it almost impossible to detect. Road users rarely see the hazard until it is too late, and because it melts so quickly, investigators find it difficult to detect.

Although emergencies, like a collision caused by black ice, can not be avoided, HTMA members take a systematic and organised approach to dealing with incidents, minimising the disruption to road users.

A wet winter

Although the UK does not have a distinct dry period, the greatest rainfall occurs in the winter. Rainfall can vary from less than 800mm per year in the South East of England, to 2,000mm in the Lake District and Snowdonia. In recent years, the amount of rainfall per season has significantly increased, with 2000 being the wettest year in England and Wales for over 200 years. In 2004, torrential rain caused some of the worst floods ever recorded in Britain. These were replicated again in 2006 and 2007.

The main causes of flooding include: a river rising due to heavy rainfall, a blocked water course, a burst pipe, a blocked drain or ditch, or land surface water flooding off a field.

Highway authorities are responsible for keeping highways free of flooding that could affect the road or highway user. This means that the winter season can cause havoc for highway authorities, especially as experts predict the frequency and magnitude of flooding is likely to increase in the future. When a highway floods it not only causes a hazard for drivers and can result in a road being closed off, it can also damage the actual structure of the road. It is therefore essential that the risk of flooding is built into winter contingency plans in order for authorities to effectively tackle the emergency when, and if, it arises.

When assessing the potential risk of flooding the following issues should be considered:

• A risk assessment should be made for any new road

• Alternative routes need to be established in case of flooding, especially for use by the emergency services 

• The capability of bridge openings and culverts in dealing with predicted levels of flooding needs to be assessed

• Flood protection should be improved where possible

A hot summer

Hot summers can also create problems for motorists and highway authorities alike. In prolonged hot conditions road surface temperatures may heat up and often do not cool sufficiently at night to prevent bituminous material in the road's construction from softening. Eventually, bitumen can become so soft that it starts to become unstable, causing sticky surfaces. In the worst cases the bitumen can even become liquid, requiring treatment to avoid severe problems. Often stone dust is applied to the surface of these ‘melted' roads. This helps to stabilise the surface and to prevent further problems.

Power cuts

In prolonged cold spells, there is the possibility that disruption may be caused to power supplies. In terms of highways this can cause a loss of power to traffic signals, street lights and control systems. Although local authorities are unable to assist with the restoration of power, it is imperative that contingency plans are in place to deal with such an emergency.

For example, highway authorities should identify specific junctions or locations where a prolonged power cut would cause severe disruption or danger, and where intervention would be required.

Round the clock service

As well as highway authorities, police have traditionally dealt with unplanned incidents and emergencies on roads such as collisions and accidents. However, under the Traffic Management Act 2004 some of the police's operations were transferred to the Traffic Officer Service, giving the Highways Agency and their contractors the responsibility to close lanes and carriageways, and stop and direct traffic.

The Traffic Officer Service patrols the whole of England's motorway network 24 hours a day, 7 days a week. There are 1,200 on-road Traffic Officers and 300 based in regional control centres.

Their main responsibilities include: dealing with emergency situations by managing traffic, closing lanes and re-opening routes as soon as possible; removing debris and abandoned vehicles from the road; providing mobile and temporary road closures, keeping the public informed of emergencies through electronic message signs and local transport reports.