SECTION 3 – TEN STEP PROCESS

The Ten Steps Required for Successful High Wind Management

Management of the impact of high wind on the road network within Scotland is currently undertaken by a variety of organisations through localised site specific agreements. Though these agreements vary from location to location as a result of site specifics and the authorities involved, each location shares the common requirement to have the impact of high wind managed effectively and safely.

The management of high wind across the Scottish road network encompasses the process of pre-planning through to active management of the wind incident. The following section defines the key steps required to successfully mitigate the impact of high wind on the road network.

Step 1 – Risk Identification

The basis of effective management depends upon the identification of exposed locations/sections of the road network susceptible to the impact of wind. Existing bridge crossings are obvious locations where high wind could impact on the operational effectiveness of the network. It is also necessary to consider other ‘exposed’ locations on the road network where driver safety can be compromised as a result of high wind.

Each road authority is responsible for reviewing sections of their network with regards to high wind and deciding on which of these sections wind management procedures should be developed for. This review could include stakeholder consultation and a review of wind related accident statistics as well as using specialist services to undertake wind profiling, climate trend analysis etc. with the aim of identifying all potential risk areas.

Risk identification acts as the initial foundation from which successful high wind management can commence.

Step 2 – Organisational Agreements

Having identified ‘key’ locations across the network, the next phase is to develop organisational arrangements to clarify the role and responsibilities of each stakeholder prior to, during and after an incident for that ‘key’ section of road. These agreements should be developed between, where appropriate, the local authority, the bridge boards, the road maintenance organisation, the police and any public information dissemination organisation involved. Although local agreements and formalities will vary from location to location, they should provide the universal function of identifying the role and responsibility of each organisation in managing high wind incidents. As part of these agreements, the decision making process and critical path for information dissemination should also be identified.

Step 3 – Diversion Route Planning

Step 3 of this process is to identify the requirement for diversion routes for extended restrictions or closures for each site and agree with stakeholders as appropriate, e.g. police, road authorities. Diversion route plans will vary in complexity dependent on the level of restriction required for each specific ‘key’ location. Diversion route plans should consider the following:

Identification of alternative routes for traffic where existing routes could be closed or subject to restriction;
Efficient diversion management to ensure drivers are made aware of alternative routes well in advance to allow them to divert to appropriate routes where applicable; and
Effective information dissemination to allow travellers to make informed travel choices in advance, ranging from safety warnings and/or diversions to delaying travelling (this is discussed later in this section).

It is essential that any identified alternative routes have been assessed for high wind impact and that these are continually monitored during a high wind incident to ensure they are not experiencing similar effects to the problem site. Additionally the safety concerns of drivers on the affected part of the network and the proposed diversion should be addressed at this stage. Diversion routes should be developed (usually by the road maintenance organisations) and agreed as appropriate between the relevant road authorities, police force, and bridge boards.

Where alternative routes are not available, temporary parking of affected (wind susceptible) vehicles in safe holding areas may be an option.

It should be noted that the decision to implement a particular diversion route rests with the local police force (who may wish to consult with the relevant road authorities). Consideration in making this decision should be given to the time required to implement the diversion and to travel along it. These times should be compared to the expected duration of the restriction or closure before deciding to implement a diversion.

Step 4 – Monitoring

Monitoring the strength and direction of wind is an integral component of high wind management. In order to effectively monitor wind, the organisation responsible for each ‘key’ location should undertake two processes. The first is to set up links/agreements with meteorological forecasters to obtain severe weather forecast warnings in advance of high winds occurring. This will enable the organisation to adopt a ‘state of alert’ to high winds and provides a window of opportunity within which the organisation can prepare for the impact of wind.

The second process is to monitor the real time wind speed, and direction as appropriate, from meteorological equipment located on the road network in the proximity of the site to allow the implementation of specific actions according to developed procedures once predetermined thresholds have been reached.

The responsible organisation should liaise with the relevant road authority to identify any existing meteorological sites available within its area and how to monitor and review this data. Where existing meteorological sites are not currently in place at the required location or are not at the optimum position, the road authority should consider a more appropriate location for a new meteorological site. Consideration should be given to the implementation of similar monitoring sites on the agreed alternative routes where these may be susceptible to high wind impacts.

Step 5 – Define High Wind Level Thresholds

In order to ascertain the level of restriction applied to each site, pre-determined threshold values of wind speed, and direction as appropriate, should be identified. This should also include threshold values at which restrictions can be removed. The level of restriction applied to each site will be dependent on site specific criteria such as road orientation or height/exposure.

The organisation responsible for each site should, through discussions with the police, road maintenance organisation and the road authority as required, identify the wind speed/direction threshold levels that will instigate agreed traffic management/ diversion procedures. Definition of these levels which will cause difficulties to traffic may require the assistance of specialist consultants to advise the authorities.

Step 6 – Develop the Levels of Restriction

Following on from the definition of wind speed/direction thresholds, the level of restriction to be applied, and the management of this, should be defined through agreement with the police, road maintenance organisation and the road authority.

Restrictions will vary dependent on wind speed, direction, geographic location and local topography. They will encompass restrictions or prohibition of certain classes of vehicles through to possible full bridge/road closure. Although organisational agreements should be established, it is essential that the organisation responsible for each site agree the restriction implementation procedures with the police as well as any affected road authorities to inform them of a proposed restriction prior to its implementation.

Step 7 – Enforcement

A key area when applying restrictions, prohibition of certain vehicle classes or complete road closures, is the requirement for enforcement. This should be agreed between, where appropriate, the police, the road authority, bridge boards and road maintenance organisations. It should be noted that appropriate signage to provide advanced warning can be used to assist in the application of restrictions.

Step 8 – Implementation of Traffic Management

Adequate traffic management is required to ensure restrictions are implemented effectively. Local traffic management procedures should therefore be agreed between the road maintenance organisation, the road authority and each relevant police force to ensure implementation of restrictions in a quick and efficient manner.

The traffic management procedures should include, where appropriate, pre-agreed alternative routes. The road maintenance organisation should, in consultation with the roads authorities, check the capacity of these alternative routes to accept the anticipated level, height and weight of diverted traffic and, during an event where diversions are required, assess the alternative route for roadworks and other incidents affecting the route. It should also provide agreed feedback on the conditions of the route to the road authority and police. This feedback should be provided prior to, during, and for an agreed period after, the restriction and associated diversion have been implemented and subsequently removed. Consideration should also be given by the road maintenance organisation to ensuring that the movement of abnormal loads is not affected.

Where alternative routes are not available, temporary parking of affected (wind susceptible) vehicles in safe holding areas may be an option.

Step 9 – Information Dissemination

A real time knowledge exchange of high wind incidents and the restrictions in place is invaluable in order to enable drivers to plan their journey effectively. The mitigation of the impact of high wind is dependent on a timely knowledge exchange between the authorities involved in managing the road, in order that response plans and procedures can be implemented successfully. As part of Step 2 (Organisational Agreements) the critical path for information dissemination should be identified. The responsibilities of each organisation for ‘alerting’ others of the incident and the time span when this should be undertaken requires to be identified at an early stage. The processes and mechanisms for undertaking information dissemination also require to be defined and agreed.

The organisation responsible for the procedures should, where possible, not only issue updates of restrictions to neighbouring road authorities, the road maintenance organisations, bridge boards etc. but should also alert the media and, where it is deemed that the wind impact and associated restriction will affect the operation of the trunk road network, the Traffic Scotland control centre. The quicker the information is disseminated to the travelling public, the greater the opportunity to minimise the impact of the restriction on the operation of the Scottish road network.

In the event of the incident being trunk road network related, the Traffic Scotland control centre and the Operating Companies will monitor and manage the status of the trunk road network. The Traffic Scotland control centre primary focus will be on the strategic trunk road network and those roads that in turn have an impact on it. Ensuring that this control centre is fully enfranchised in the decision making process and provided with timely information will enable it to distribute information to the travelling public both quickly and efficiently.

There is an obvious inter-dependency on all classes of road across Scotland. Where an incident occurs on any one key section of the network, it will have a knock-on effect on the other road links to and from that road, whether trunk or non-trunk. As such, interaction between the trunk road network and non-trunk road network agencies is clearly required to manage such incidents and return the overall network to its optimum efficiency as quickly as possible. Close liaison between road maintenance organisations, bridge boards and local authorities is necessary to facilitate this.

Full consultation, agreed involvement and interaction are therefore vital for the successful management of the impact of high wind affecting these locations and the road network linking them.

Step 10 – Relaxation of Restrictions and Information Dissemination

The decision-making process regarding the relaxation of restrictions requires to be clearly defined for all stages of a wind management event. Any relaxation will be determined by a combination of meteorological forecasts and observed real time wind speed and direction.

It is essential that the organisation responsible for relaxation of the restrictions liaises with the police, the road authority and the maintenance organisation to confirm acceptance of this relaxation prior to the removal of restrictions.

Any relaxation of restriction must be communicated to the travelling public to allow the network to return to its normal operating conditions as quickly as possible.