Frequent issues addressed by the Diales civil and structural team
The structural and civil engineering design process is inherently complex, involving multiple professionals from different disciplines. Engineers, architects, contractors, and other stakeholders must collaborate to ensure that all elements of a project come together seamlessly. A critical challenge in this process is managing interfaces; those points where different systems, materials, or structures meet.
Author: Stuart Holdsworth, Technical Expert, London, UK
Poor communication and lack of coordination at these interfaces can lead to significant issues, including compatibility issues, disputes, delays, and costly design errors. This article explores the importance of ensuring that, from the project outset, interfaces are identified and that management of them is addressed. It also explores the idea that communication between owners/ employers, project managers, and designers is a critical component in achieving a successful delivery of a project, as well as the consequences of poor coordination. Some examples of problematic interfaces are examined.
The importance of communication between stakeholders
At the heart of any successful construction or engineering project, clear, precise, and effective communication between all the parties is necessary. In structural and civil engineering design, projects are rarely the work of a single entity. Cooperation must be built in from the project inception. Collaboration between the project stakeholders, including the owner/ employer, project managers, structural engineers, civil engineers, architects, MEP (mechanical, electrical, and plumbing) engineers, and specialist subcontractors is essential. Each specialist contributes their expertise to the project, but they may also rely heavily on the experience and knowledge of others to ensure that the overall design is coherent and integrated. Limitations in each party’s scope of works and division of the project into work packages create a series of interfaces. They are introduced at the outset with the distinct purpose of establishing clear and precise boundaries for each party's work share. Each interface is commonly conditioned by a change of structure or architecture that defines a clear break in the form and function of the elements. Examples of this include the boundary between a building’s frame and its façade, or the track bed of a railway and other rail-related infrastructure, such as tunnels, bridges, signalling systems, or vehicle specification.
Such works may involve a hierarchy in which parties may be dependent upon the appointment of a lead contractor so that the works can be coordinated. This is a common feature of transport projects. It is essential in such cases to manage the contract procurement stages to reflect this hierarchy. The shared feature(s) at such boundaries require careful investigation to ensure that the objectives of each of the interfacing parties are properly addressed. This typically involves agreeing on a common specification, usually comprising an agreed performance and set of tolerances, for the interface which will ensure compatibility between the work phases. Without careful investigation and management, these interfaces can become points of conflict in which the project management, conflicting requirements, assumptions, or design philosophies lead to serious issues with the construction. The introduction of late changes to the design or procurement process, requiring re planning and scheduling, or remedial works, inevitably introduces delays to project delivery with resulting claims. To avoid conflicts or lessen the risk of them occuring, it is vital that all parties involved in the design process have a deep understanding of the interdependencies of their work. Project managers, commercial managers, architects, etc., involved in setting the boundaries at the outset and who later control and manage the works must clearly understand the consequences of introducing these boundaries. Failure to manage interfaces will commonly result in each party adopting the commercial approach that suits their aspect of the work, including the adoption of more stringent technical standards, which can result in an incompatibility in the contracted works at the interface.
With all projects, and particularly for those in which the design is subcontracted to specialist subcontractors, it is also important to have a clearly understood process for sharing information, conducting design reviews, and resolving any discrepancies that arise. The use of BIM (Building Information Modelling) is an example of a technological tool designed to improve communication between stakeholders by allowing for the visualisation and coordination of all aspects of the design.
Examples of problematic interfaces
Coordination issues can result from a temporary requirement or a permanent works requirement. Temporary issues commonly result from a lack of understanding or experience of the requirements relating to testing, or stability not being specified and thus understood. Permanent works interface issues commonly occur because of compatibility issues between the structural frame and interior and exterior architectural and MEP elements.
Permanent conditions
- Façade engineering and structural frames
One of the most common areas where problematic interfaces occur is between a building’s structural frame and its façade. Façade engineers are typically responsible for designing cladding systems that protect the building from the elements and provide aesthetic appeal, while structural engineers ensure that the building can withstand various loads, including those from the façade. Structural engineers in the UK work to a set of advisory deflection limits codified in British Standards. These limits are not always compatible with interior finishes or external cladding tolerances. In such cases, a bridging interface is required. To resolve this interface the compatibility issues arising must be included in a party’s contract, with clarity as to the issue being addressed. This is usually performance related and can include the overall allowable deflection, the live load deflection, and air and fire sealing, etc.
- Foundation and superstructure coordination
If there is a division in responsibility between the building elements and foundations, there are risks that require management at the interface. This is particularly so where basement structures are involved, and cladding and interior finishes interface with them. Heavy machinery foundations and other mechanical elements with subcontracted structure can also lead to complicated interfaces with the remainder of the substructure.
- Mechanical systems and structural design
MEP systems present another potential point of interface problems. These systems are typically integrated into the structure during construction, but their design must be closely coordinated with the structural engineers to ensure that they do not interfere with the building’s architectural and structural performance. For example, MEP engineers commonly need to run large ductwork and duct work risers through floors or walls. These require large openings that can compromise the structural integrity of the surrounding structural elements. If the structural engineers are not made aware of the size and location of the ductwork, a delay as the structure is redesigned will occur or, if discovered post contract, will result in structural issues, requiring some degree of reconstruction, compromise, and strengthening works, with a consequential loss of value, disruption, and delay, or an underperformance in the originally specified structure.
- Utilities
The provision and location of utility supplies is for the most part outside the direct control of any developer or contractor. The timing and route of any connection must be agreed well in advance of the required utility work being implemented by the relevant party. If this work is critical to the function of the development, which it is in almost all cases, then the routing and construction sequence requires careful coordination with the build. This is to ensure the utility work does not impact upon the construction and progress of the development but is timed to be available when required, particularly so if the utility company is responsible for the complete package of the works such is commonly the case with public transport schemes.
Temporary conditions
Temporary conditions can also cause issues if they are not properly understood and considered. It is obvious that if the construction requires temporary works to allow the formation of the permanent structure, then working room and interfaces and connections for the temporary works must also be provided. A less obvious example is conditions that involve water. Empty pipes/containers and swimming pools in water bearing soils when temporarily sealed or emptied of water will float and, if insufficiently ballasted, lift or displace from their correct alignment. Similarly, gas pipes require pressure testing, and when connected to external structures, can fail if insufficient support is provided for the flooded condition under which the pressure test is undertaken.
Avoiding disputes and improving interface management
To mitigate the risks associated with problematic interfaces in structural and civil engineering design, several best practices can be implemented. First, clear delineation of responsibilities must be established at the outset of the project. Each party must fully understand their role in the design process and the areas where their work interfaces with others. Above all, there must be a single controlling mind or body capable of identifying and addressing the issues that are caused by contract boundaries, particularly those which are hierarchal, or performance related and that require detailed specification and addressing in the work schedule at the time of contract. The use of BIM and other collaborative design tools can significantly improve communication by providing a shared platform for all stakeholders to access the latest versions of the design. BIM can identify clashes and issues relating to the detail design of components but will not resolve issues of responsibility that required addressing at the contract stage. Regular coordination meetings where potential interface issues can be further reviewed and resolved early are also crucial. Finally, the adoption of robust contract frameworks that clearly define the process for handling disputes and allocating responsibility for any issues can help to minimise the legal and financial risks associated with problematic interfaces. When disputes do arise, Alternative Dispute Resolution (ADR) methods, such as mediation, expert determination, or, arbitration, are often preferable to litigation, as they can provide quicker and less adversarial solutions.
Conclusion
It is essential for the timely and on-budget delivery of a project that critical interfaces are addressed at the contract stage. Identifying these interfaces at the outset will help ensure their successful management of them, which is critical to delivering the project, and ensuring the safety, efficiency, and cost-effectiveness of the project. Post contract, the effective management of the project requires active communication between the various parties and design teams. Such communication plays a critical role in minimising the impact and avoiding any further issues that can arise at key points of interaction between the teams. If this communication fails, the results can be costly, leading to design errors, delays, and disputes. By improving coordination and using technological tools to enhance collaboration, those enabling projects can help minimise the risks associated with problematic interfaces and ensure that their projects proceed smoothly from design to construction.
This article was originally written for issue 28 of the Diales Digest. You can view the publication here: www.diales.com/diales-digest-issue-28
To discuss any of the points raised in this article, or to enquire about our project management services, please email: stuart.holdsworth@diales.com