The Mersey Queensway Tunnel, when opened in 1934 was the first purpose built road tunnel in the world. The Dartford and Tyne tunnels opened in the 1960’s followed by Mersey Kingsway and from then the UK toll tunnels started work collaboratively.

In the 1990’s the Highways Agency (HA) started contracting out their operation and maintenance. Many of the agent consortia had little experience of tunnel operation and maintenance. To address this, the Agency called a meeting of all operators of tunnels on their network together with the three toll tunnel operators. This was the beginning of the Tunnel Operators Forum.

Tunnel Operators though felt a need for a separate association. Over the last three years the embryonic Tunnel Operators Association (TNO) has agreed objectives, terms of reference, a draft of their constitution, membership and new Logo. These are expected to be finalised and agreed at a meeting in October 2007.

Objectives of the Association

The TNO represent road tunnel owners and operators, focussing on collective views on tunnel design, equipment, operation and maintenance standards. Also it will contribute towards harmonisation of EU Directives, national standards and legislation, PIARC Committee/Working Group proceedings and recommendations, and European Tunnel Test Standards.

It will also support the needs of Tunnel Operators by establishing standards and means of validating standards with particular reference to staffing functions, expertise, training, certification and legal obligations.

The drivers behind the big issues for tunnel operators are the requirements of legislators, the needs of users, the responsibilities and needs of the operators themselves and importantly safety!

The requirements of legislators are defined in the DfT and HA standards primarily BD53/95, which is currently being revised, and BD78/99 together with the European Directive 2004/54/EC, which is shortly to be embodied in a Statutory Instrument adapted to UK practice. The EU Directive calls for:

  • Maintenance Standards and Condition Monitoring
  • Structural/Visual inspections every 2 years
  • Structural examination every 6 years
  • M&E Visual inspections every year
  • M&E testing every 3 years

There are much greater requirements in the Directive than previously for monitoring and maintenance as well as dictating major refurbishment on older tunnels. It is noted that the EU Directive only applies to TERN (Trans-European Road Network) tunnels, but is regarded as good practice everywhere.

The responsibility of the Tunnel Operator is to ensure the most effective efficient use, operation and maintenance of the facility and to manage safety. Safety management is three dimensional including, safety as set out in the legislation, safety of employees and contractors under the Health and Safety at Work Act, and safety of the users.

While these responsibilities seem straightforward, they often conflict. Uninterrupted operation conflicts with maintenance and the three strands of safety management need handling carefully. Few tunnels have diversion routes in the event of tunnel closure and maintenance work within the road space normally requires closures (Table 1). The use of convoys is not common but is used on an hourly basis in the Tyne Tunnel during night time maintenance, as there is no reasonable diversion route.

Effective Traffic management is imperative for the facilitation of tunnel maintenance and include distant advance warning and diversion routes, total clarity in the near approach and portal areas, and adequate control within the tunnel. Tunnel equipment which can be rapidly and economically deployed and removed should be installed. A good knowledge and understanding of traffic patterns, driver behaviour and secondary consequences throughout the day and night is essential. Good public relations and timely public information arrangements are also invaluable.

Practice and safety considerations

Most maintenance work requiring traffic restrictions will best be done when traffic is at its lightest. This may be weekday nights with possession periods of between 6 – 10 hours or weekend work with possession periods of up to 60 hours at bank holidays.

Because of the limited access windows, design for easy access and minimum maintenance is a priority. This has implications for the layout of the tunnel and its equipment. Careful design will reduce the need for lane closures. Design using Plug and Play principles where equipment is removed from its installed position for maintenance and replaced by a spare unit can be effective in reducing the time required for closures. Robust Design of equipment to minimise maintenance, duplication and backup of equipment to reduce the criticality of failures are important.

The three dimensional nature of safety management needs to be recognised. That is the safety of:

  • Tunnel infrastructure
  • Traffic and vehicle occupants
  • Tunnel operator employees

Conflicts between these aspects need to be managed as the Operator attempts to meet increasingly rigorous safety standards .

Future trends and conclusions

With costs of skilled maintenance workers increasing, the costs of mass produced goods decreasing and reliability/durability improving, Run to Fail (RTF) has to be considered as a design philosophy for tunnel equipment. Traffic is increasing, the standards for tunnels are increasing and with that the need to refurbish older tunnels.

The issues affecting operators must be taken into account at the design phase. An example is when considering the advantages of building three parallel bores with two lanes per bore compared with two bores with three lanes per bore. The latter gives more flexibility with respect to managing any tidal flow or maintenance closures.

With increasing political pressures and lack of tolerance for delay it must always be remembered that safety cannot be compromised in tunnel design and operation.