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Bracklinn Falls is situated in a gorge surrounded by ancient woodland within the Loch Lomond and the Trossachs National Park. The park authority required a replacement footbridge to cross the gorge and to provide views of the falls. However, access for construction plant and materials was extremely difficult, with the sole access by way of a steep and sharp-cornered path. The construction and access constraints drove the development of a new modular system and governed the structural and aesthetic design for the new footbridge. The resulting structure consists of perforated panels, formed from single sheets of weathering steel folded into a z-shape. These panels were bolted to cross-frames and assembled to create a half-through beam that spans 21.4 m. The scheme achieved an A+ rating under the 'structural carbon for bridges' (SCORBs) system (Archer and Green, 2021). The structure was assembled bay by bay and push launched along a set of temporary rails, then jacked onto the permanent bearings. By using a folding process, the modular system minimised welding and hence fabrication time. The system is in the process of being developed for repeated use at other locations, and forms an attractive 'flat-packed' modular alternative for difficult to access locations. [ABSTRACT FROM AUTHOR]

In complex networks such as road infrastructure systems, disruptive events have direct consequences (loss of lives, structural damage, economic losses, etc.) related to the sub-system level directly affected, as well as indirect consequences on the overall system level, such as loss of functionality and related monetary consequences. To quantify the influence of component failures on network performance, complex network analysis makes it possible to represent the relation between its components and the consequences to estimate the functionality of the system. The serviceability of a road network is the possibility to use it during a given time period, and represents the performance of the system. Thus, time to restored serviceability after a disruptive event is a measure of road transportation resilience. In this paper, network analysis performed by the OSMnx Python package, supplied by road network data from OpenStreetMap, is applied to a Spanish motorway case study. The loss of serviceability index is obtained, combining the results of road links failure scenarios based on shortest paths and travel times to estimate road network resilience. The proposed methodology allows a suitable evaluation of the influence of road links in the risk assessment and management strategies by road infrastructure owners and managers. [ABSTRACT FROM AUTHOR]

Over the past 15 years, there have been some research outcomes in other disciplines that could be used to produce new, more accurate and realistic numerical models to characterise pedestrian loads and to significantly improve predictions of response for multiple-pedestrian scenarios. However, the disconnection between fields has not facilitated this further research. Using this, the paper presents (a) a new sophisticated load model that includes a description of vertical and lateral loads, including pedestrian–structure interaction, (b) the numerical description of relationships to describe the key parameters of the proposed model and (c) the evaluation of the effects of pedestrian characteristics that are relevant for serviceability response of footbridges. The proposed new load model allows for the inherent variability of individual pedestrian actions (intra-subject variability), a probabilistic description of how pedestrian characteristics vary among subjects (inter-subject variability) and collective human behaviour (pedestrian–pedestrian interaction). Some of these characteristics are not currently considered in design approaches and can have a substantial impact on structural response assessments. Finally, recommendations are made for many of these characteristics to be introduced in analyses to evaluate the vibration serviceability limit state of footbridges in a more accurate and realistic manner. [ABSTRACT FROM AUTHOR]

The historic Old Tweed Bridge is a three-span listed masonry arch crossing the River Tweed. Structural integrity concerns resulted in the bridge being temporarily closed to the public and propped. This paper discusses the challenges associated with the construction works necessary to refurbish the bridge permanently. The works involved installing a temporary propping and encapsulation structure, excavating the bridge infill, taking down and rebuilding the walls, casting a concrete saddle above the arches, waterproofing and resurfacing. Other innovative works involved closing the gap between the voussoirs and arch barrel using a bespoke arch pulling system and repairing voussoir stones in situ with a lime-based material. There were significant environmental challenges on the project as the bridge is located in an ecologically sensitive area. The River Tweed is one of the UK's great salmon rivers, which restricted working in the river and required strict pollution controls. Alternative roosts for bats were provided and netting was required around the bridge as part of an advanced works contract to mitigate the risk of birds nesting in the bridge. [ABSTRACT FROM AUTHOR]

The new pedestrian and cycleway crossing of the River Mourne in Strabane, Northern Ireland is a slender lightweight cable-stayed structure. The bridge is 96 m long in total, with a main span of 80 m. The bridge is characterised by its inclined main tower, curved in elevation and very slender deck profile. This bridge was designed in such a manner to avoid the use of proprietary damping systems that can be employed to avoid the risk of exceedance of serviceability criteria in similar structures with a view to minimising maintenance costs during the life of the structure. This was achieved using careful dynamic analysis of the structure, wind tunnel testing as well as post-construction testing to validate criteria not explicitly dealt with by the codes of practice. This paper describes analysis and testing undertaken for the dynamic design of this bridge resulting in the client's vision being realised. [ABSTRACT FROM AUTHOR]

This paper describes the design, analysis, fabrication and testing of portable pedestrian bridges for disaster relief. Two main ideas were used in the design of these bridges. One was the pantograph mechanism exploited to expand bridge structures rapidly and the other was the rigid body rotation of the bridge deck utilised to span a river without piers. Numerical simulations and experimental results showed that the bridges developed satisfy the specified design requirements. This study may provide engineering consultants with design concepts for rescue bridges that are convenient to store, carry, assemble, install, dismantle and reuse. [ABSTRACT FROM AUTHOR]

Bridge design and construction has gone through several phases in Southern Africa. The first phase was dominated by steel. During this phase, revolutionary steel bridges were constructed. This happened despite the fact that steel was not manufactured in this region. The use of structural steel in these bridges exploited its advantageous properties of economically carrying heavy loads over long spans with minimum dead weight. After this phase, the choice of material used in bridges changed to concrete. During the past 20 years, steel has staged a strong comeback. The aim of this paper is to explain why the bridge industry has experienced different phases in construction. Selected case studies of vehicle and foot steel bridges are presented and discussed to substantiate the competitiveness of steel as a bridge construction material. [ABSTRACT FROM AUTHOR]

Londonderry in Northern Ireland is a city divided both physically and symbolically by the River Foyle. As part of an integrated programme of regeneration for the city, a new pedestrian and cycle bridge was constructed to provide access from the historic city centre to a new mixed-use development on the opposite side of the river. Because of the symbolic significance of creating a link between the historically divided communities on either side of the river, the bridge was named Peace Bridge. The 310-m-long curved self-anchored suspension structure was opened in June 2011 and has already become a landmark for the city. This paper describes how the client's requirements were incorporated into the unique design and summarises the main elements of the detailed design and construction. [ABSTRACT FROM AUTHOR]

A prestressed concrete stress ribbon footbridge is a type of suspension bridge without towers. A conventional stress ribbon footbridge has two types of tendons in the concrete deck: the internal prestressing tendons (secondary tendons) and suspension tendons (primary tendons), which carry the dead load. This study targeted two footbridges with common structures that efficiently arrange the external tendons to reduce the construction cost and match the surrounding landscape. The Morino-Wakuwaku Bridge has the suspension tendons (primary tendons) in the concrete deck, and the prestressing tendons (secondary tendons) are placed outside of the deck as the external tendons. The Ohmaki-Dondo Bridge has external tendons (primary and secondary tendons) and bearings. These bridges differ in their structural and vibrational characteristics. Static loading tests using a vehicle, vibration tests using humans and finite-element method simulations were carried out to understand the characteristics of each bridge. This paper describes the structural and vibrational characteristics of prestressed concrete stress ribbon footbridges with external tendons and estimates their vibration serviceability performance for pedestrians based on the analysis and test results. [ABSTRACT FROM AUTHOR]

The Jarrold Footbridge in Norwich, UK opened to the public in January 2012, linking the new St James Place development to the historic city centre. As well as providing a crossing, the bridge invites visitors to linger, enjoy the river environment and make the most of distant views of the magnificent cathedral. This case study describes how the form of the bridge evolved from the unique characteristics of the site and the engineering logic, which substantiates this subtle structure. It describes the structural principles, which enabled the architectural concept for a bridge that gently floats across the water with little apparent support. This paper relates the whole design and construction process; how parametric three-dimensional modelling was used to trace the most efficient path through interwoven sustainable transport routes and the natural features of the site. It describes the structural optimisation process and the reality of translating the sweeping curves of the geometry into steel and timber. Finally, this paper explains the use of software in design and the positive implications for collaborative working in construction. [ABSTRACT FROM AUTHOR]

A new moveable footbridge was recently built at the entrance of Marina Atlântico in the city of Viana do Castelo, Portugal. This paper presents a brief description of the global solution, with a special focus on the characterisation of the construction methods adopted. Particular consideration is given to the construction of the pivot pylon and the steel structure, showing how all the bridge components work together to ensure a safe working relationship with the marina, the river and users of the continuous bicycling and pedestrian pathway running across the closed bridge. The mechanical, hydraulic, electrical and navigational light systems play fundamental roles, especially during bridge opening and closing operations. Moreover, as this light footbridge is susceptible to vibrations due to human traffic, the paper also describes the dynamic tests performed during and after construction, including two ambient vibration tests, the measurement of cable-stay forces, and tests with groups of pedestrians used to evaluate induced vibration levels along with the monitoring of bridge accelerations over 4 months of use. [ABSTRACT FROM AUTHOR]

Little effort has been made to develop a life-cycle management system for small or medium-scale projects, such as the provision of footbridges. As the number of footbridges keeps increasing, there is a need to develop an optimal management strategy to optimise the cost of design and construction, as well as the cost of future actions such as maintenance, inspection and repair. However, while footbridges tend to be built in the form of networks, in most existing life-cycle management system research and practice, bridges are treated individually rather than as a bridge network. A new life-cycle management system for footbridges is therefore needed. The objective of this paper is to propose a framework for a life-cycle management system of footbridges which consists of three management levels - component level, project level and network level - in order to manage footbridges as a united network. The management approach and the dominant components of the proposed framework are introduced and application of the framework to Hong Kong provides an illustrative example. [ABSTRACT FROM AUTHOR]

In 2003 a group of structural engineers founded a new group within the charitable organisation 'Engineers Without Borders Germany'. Inspired by the work of other non-government organisations, they set off with the goal of applying their engineering knowledge to post-disaster relief work and infrastructure development in countries where it was most needed. Over the past 10 years the group has grown into a team of engineers, architects and students spread across Germany who plan, design and execute bridge projects in developing countries. The initial projects were footbridges built in Rwanda, but the scope has expanded ever since. The group aims at providing sustainable design and construction, which means that locally available materials and construction techniques are to be preferred. Further, the training of local engineers is considered important for providing a lasting infrastructure that can be maintained by the communities themselves. To this end, training workshops have been held and a strong relationship with a local university has been established. This paper describes the challenging work of providing safe yet efficient bridge designs and outlines the execution of some projects. It also describes the history of the group and outlines some of the work undertaken in research and development. [ABSTRACT FROM AUTHOR]

The article discusses the important mechanical aspects that are to be considered during the installation, commissioning and handover of moving bridges. Among the critical aspects include the bridge operator and control position, selection of drive system, and bride control and sensing requirements. Furthermore, it cites the significance in reducing the need for maintenance during the design process, as well as in ensuring thorough and complete training for maintenance and operating staff.

Within the framework of the French National Research Project MIKTI dealing with ‘composite steel-concrete footbridges and bridges for tomorrow’, a loading test was performed in Belgium on a railway bridge deck consisting of simply supported composite ‘Preflex’ beams. The bridge was 30 years old at the time of the test so the timedependent stress redistribution between the steel of the girders and the concrete was almost stabilised. The bridge deck was loaded progressively by two heavy diesel-electric locomotives. A 4 m long zone situated at the mid-span of the deck was instrumented and monitored during the loading test. The following measurements were taken: the mid-span deflection; the slopes in five locations; the length variations of 16 extensometers of 250 mm length situated near the bottom fibre of the beam and acoustic emission. All of the measurements showed that the behaviour of the bridge deck under the test load was linear elastic, the concrete was not cracked before the test and no cracking appeared in the concrete during the test. The concrete part of the cross-section fully contributed to the stiffness of the beam, confirming the excellent long-term behaviour of this kind of railway bridge, even after a very large number of live load-cycles applied on them during more than 30 years of service. These observations are in very good agreement with the values of stresses computed by a step-by-step method, applying the principle of superposition of linear viscoelasticity for modelling the time-dependent stress redistribution in these composite beams. [ABSTRACT FROM AUTHOR]

The article offers information about the eight newly designed and constructed footbridges in Poland. It is stated that the structures have been designed in an original and aesthetic way to create bridge over the highway, helping drivers in identifying their location and creates a new landmark in the surrounding area. On the other hand, the newest of the footbridges presented was built in 2004, in Ruda Slaska.

This paper describes the design development of a low-cost pedestrian and cycle bridge recently constructed across Garyllis River in Limassol, Cyprus. Three identical trusses provide the basic span crossing, and the top and bottom geometrical shape of each truss is parabolic. The slabs spanning the curved topmembers of the trusses form the pedestriancrossingwhile the beams extendingas cantilevers on either side of the curved bottommembers provide support for the two cycle paths. The central truss is vertical while the tops of the two side trusses are inclined inwards. This configuration produces a gently curved cycle path and a narrowing and then widening central footpath. It also causes the cycle paths to have an inward slope and the footpath to have an outward slope, thus improving the feeling of safety. [ABSTRACT FROM AUTHOR]

This article reports on the construction of footbridge in Heath town, Wolverhampton, a replacement of the old concrete bridge built in 1960's. A feasibility study was produced to ensure the success and firmness of the project. The study offered different styles and options as to what design the public would like to. The Wolverhampton City Council opted to choose a twin steel arch with an estimated cost of £600,000. The footbridge was completed on September 9, 2000.

The article focuses on the importance of efficient dynamic performance of footbridges. There has been an increasing demand for assessment of the performance of new and existing footbridges subject to pedestrian loading scenarios. The article describes an efficient procedure for assessing dynamic characteristics and performance using a combination of visual survey, finite-element modelling and brief and unobtrusive dynamic testing, followed by short observation of pedestrian-induced response and finite-element model updating for evaluating other loading scenarios. The procedure involves minimal effort for maximum effect, generating a reliable analytical representation for response simulation and checking the serviceability of the bridge.

The article discusses the design and construction of the Sail Bridge over the River Tawe at Swansea, South Wales. This footbridge represented a key element in the regeneration of the disused docks area, unlocking the potential for the new Port Tawe Innovation Village under development by the Welsh Development Agency. The development of the design and construction includes the selection of the bridge form along with the use of computer modeling techniques to develop the complex geometry, fabrication and bridge erection issues, aerodynamic investigations and the design of tuned mass dampers to control potential pedestrian-induced vibrations.

This article describes the replacement of a failed timber footbridge in Cumbernauld, North Lanarkshire, Scotland. It aims to recognise the importance of providing and maintaining sustainable walking and cycling links within an urban environment. It emphasises the significance of sustainable development in urban regeneration, and the need to develop the existing pattern of usage of walkways and cycleways, thereby encouraging healthy alternative means of transport, and avoiding the promotion of a culture where short journeys are made by automobiles.

The article discusses moving load testing of footbridges. Dynamic load induced in the vertical direction by a single person walking across a footbridge structure is usually modelled as a resonant harmonic force. Using this harmonic force for predicting the response of a perceptibly vibrating footbridge can significantly overestimate the real footbridge response and therefore its degree of liveliness. The article proposes a methodology for systematic comparison of the measured and simulated responses with the aim of identifying vibration levels which disturb normal walking. Also, the observed effect of losing steady walking step can be showed via either increased damping or modified harmonic dynamic force over time periods when test subjects lose their step.

The article presents information about assessment testing of Mizen Head Footbridge in Ireland. An inspection and structural evaluation of the bridge was carried out in 2002. Specific information on the structure was collected by material tests, observations and geometrical surveys. This information helped establish the condition of the structure, material and geometric parameters for analytical models, and future maintenance, repair or strengthening requirements. The defects noted during the inspection may be summarized as rust staining, areas of hollow-sounding concrete, cracking and localized areas of missing concrete.

The article compares the theoretical prediction of the critical number of pedestrians and shows close agreement, with the results of full-scale tests on the Millennium Footbridge of London, England. The Millennium Bridge is essentially a three span shallow suspension bridge, with vertically and horizontally curved suspension cables supporting a 4.0 meter wide, lightweight steel and aluminum deck. Subsequent investigations revealed that the dynamic characteristics of the bridge did not differ significantly from those of other footbridges of similar spans, and that the phenomenon of excessive lateral vibration had occurred in other bridges.

This article reports that in June/July 2000, shortly after the opening of the London Millennium Bridge in Great Britain, experiments were undertaken on a full-scale section model built to represent a footbridge swaying under pedestrian action in Great Britain. The processes of human-structure interaction and the phenomenon of phase synchronization were investigated. Various instabilities were observed using 3D motion capture equipment, and lateral forces were inferred from the dynamic response of the rig. The first lateral mode of the central span of the Millennium Bridge was simulated by creating a three-bar linkage. The diagonal bars represented the cables and the central rigid body the deck. The bridge deck was assumed to contribute little to the lateral stiffness: thus all stiffness of the model was provided by gravity. The dimensions of the mechanism were obtained from sketches and photographs of the full-scale structure.

An introduction is presented in which the editor discusses various reports within the issue on topics including railway bridges, management of footbridges and girder bridges.

An introduction to the journal is presented where the editor discusses various reports published within the issue on topics including applicability of Eurocodes on bridge engineering, methods to monitor and align cable tension in cable-stayed bridges and footbridges for Dubai metro in Dubai.

The article presents information on the restoration of Bersted Crossing footbridge at Bognor Regis in Great Britain. This lattice girder rail bridge is constructed out of wrought iron, during the later part of the Victorian era. The restoration plan for the bridge was proposed due to its poor aesthetic condition. But the bridge was in good structural condition.

The article provides information on reports included in this issue on construction of footbridges in Great Britain. In recent years there has been a step change in thinking and a realization to the impact footbridges can have on people's well being. For a long period of time, cities and towns were laid out on the basis of the car, often to the exclusion of those wishing to walk or cycle, and certainly not offering any encouragement to do so. People want cities to be places for people, built and maintained on the principle that people come first. The Gateshead Millennium Bridge is one of the many examples of catalysts for transformation.