Stunts on bridges cause concern

This is an extensive and difficult subject area that has considerable sensitivities. Stunts, as described, could be unplanned (for example dares and drunken incidents) or indeed planned (for example protesters). Extremely important questions arise as to how far infrastructure designers and clients should go to counter inappropriate behaviour, vandalism and malicious acts or indeed other behaviours such as when people are not of stable mind. These questions arise for many types of building and civil engineering structures.

The designer alone cannot deal with all the potential areas of misuse by members of the public. Designers, clients, operators and users should contribute to risk assessments and agree upon design solutions and any misuse mitigation measures that are appropriate. It may be appropriate to include parties such as police, local authorities or health boards in related discussions since the issues may be far wider than engineering problems. Solutions often benefit from the input of a far wider range of disciplines, especially those professionals who understand the minds of people with suicidal tendencies. The danger to children gaining access to structures and treating them like a playground is an ongoing problem which must be addressed. Malicious acts that could have disproportionate consequences should also be given consideration. The Government’s Centre for the Protection of National Infrastructure (CPNI) provide guidance on protecting critical infrastructure against malicious acts.

Mitigation measures should be reasonable and appropriate. It can often be difficult to find this balance, for example with listed structures. Requirements may change over the lifetime of the structure. Mitigation measures conceived at a design stage may need to be adapted over the service life of the structure as society and the environment local to the structure changes. Installing mitigation measures can create a ‘challenge’ that some people may find irresistible. Non-engineering approaches such as maintaining good visibility may be helpful. Different sectors will have different approaches – the rail sector for instance, will consider ‘threat and vulnerability assessments’ as well as security measures in the design of infrastructure. Measures such as anti-climb, omission of flat surfaces or means to gain grip, CCTV and signage may be considered alongside active measures such as public address announcements, help lines, neighbourhood and emergency service initiatives. Trespass risk assessments to industry standards are also undertaken. Clearly, strategies to prevent inappropriate access to arch bridges will be considered by designers and clients. As put forward by the reporter, emerging personal transport modes (such as e-scooters) may require alternative mitigation measures to those previously adopted. As with all design, the earlier such matters are addressed in the design process the more likely better outcomes will be found.

In conclusion, designers must keep in mind good sense (if something is clearly an 'invitation to climb' it needs guarding), but designers must also be aware of emerging trends in society so that good sense is kept up to date. It is very doubtful that rules can be set down, or (even if they could) that they would remain static. Designers must therefore have time to engage such that they can stay alert to how designs can develop to take account of the society that engineering serves.