Over the past few decades, engineers working in design offices have become much better at designing for constructability. The use of the design and build form of procurement has, in many ways, been instrumental in this change. The use of accelerated bridge construction in the USA, although primarily a method of reducing traffic impact, has also helped engineers become better at designing for constructability. However, it can be argued that engineers have not made the same progress in designing bridges to make future inspections and maintenance easier. In fact, unless an employer's requirements for inspection and maintenance are clearly prescribed in detail in the contract, then the design and build form of procurement is perhaps the least advantageous when considering the service life of a structure. Over the lifespan of a bridge, the service life costs, including inspection and maintenance, can account for a significant percentage of the lifecycle costs of the bridge. Therefore, the importance of not only ensuring that an adequately funded proper inspection and maintenance regime is established but also that sufficient attention is paid to the provision of inspection and maintenance during the design stage cannot be overstated. This paper examines and compares current practice in the UK and USA and considers ways of improving the design process to assist the future inspection and maintenance of bridges.

<p>The majority of suspension bridge cables consist of thousands of high-strength galvanized steel wires typically around 5mm in diameter. The wires are compacted into a near-circular shape then traditionally protected by externally applied red lead or zinc paste, galvanized wrapping wire, and paint. As evidenced by cable inspections, water inevitably intrudes into the interstices of the cable causing atmospheric corrosion, hydrogen-induced stress corrosion cracking and broken wires.</p><p>Since its first application on the Akashi-Kaikyo Bridge in Japan, cable dehumidification has emerged as an effective method of protecting cables from the damaging effects of water. This paper will discuss the types of suspension cables, traditional cable protection systems, typical findings from internal cable inspections, and the history and effectiveness of dehumidification as a technique for protecting the main cables of suspension bridges.</p>

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<p>This paper discusses three latest practices applied to existing US long-span suspension bridges. The first is the moveable median barrier (MMB) along U.S. Highway 101 on the Golden Gate Bridge that was recently installed. This MMB system enhances traffic safety by providing a physical barrier to separate opposing directions of traffic, while at the same time allowing the reconfiguration of the lanes to meet peak capacity demands. The second is the suicide deterrent barrier system (SDS) to be installed on the Golden Gate Bridge, the first of its kind in the United States. The Net system was identified as the Preferred Alternate in the FEIR/EA process to be carried forward to final design. The third is the corrosion protection of main cables by dehumidification, first implemented in the United States on the William Preston Lane Jr. Memorial Bay Bridge and now being planned or implemented on other US main cable suspension bridges.</p>

<p>There is recognition that inspecting all elements of a complex bridge at the same set frequency is not suitable for these types of structures and an inspection regime that uses a risk based approach is more appropriate. However, there is no formal method or guidance on how such an approach should be applied to complex bridges. This paper sets out a method of inspecting complex bridges based on the evaluation of risk. An assessment of the criticality, vulnerability and current condition of each bridge component or groups of components is carried out to determine the frequency of inspection based on the risk of failure. This assessment also takes into account the degree of difficulty of detection by inspection. This method reduces the risk of failure, optimizes resources and can help reduce risk to the public. This risk based approach can also be developed for use in maintenance and capital works planning and this will be introduced in this paper.</p>