Offsite innovation in UK infrastructure: the role of the approvals process in box jacking projects

In the UK civil engineering major roads and rail sectors, novel uses of offsite methods of construction have commonly "required special approval" by governmental body approval processes and Codes of Practice. Understanding the ways that such organisations influence the sector’s confidence regarding innovative construction methods and materials could help accelerate their development in the design and construction process, and hence also help maximise the possibilities of modernisation in the sector. By comparing two case studies of offsite precast concrete underbridge box-jacking, one as part of a government authority responsible for motorway contracts and one with a government authority responsible for railways, the differences regarding prioritisation of acceptable risk are explored. The main drivers and constraints for offsite adoption and implementation are investigated and presented. Key challenges during the design and construction period of the projects are identified. These focus on establishing effective communication between clients, designers, contractors and offsite suppliers/sub-contractors when implementing offsite, as well as understanding aspects of the physical integrity of assets that are dependent on the limitations of essential availability, disruption of usage or closure. By considering the differences in approach towards innovation and approval systems for the Governmental approval agencies responsible for motorways and railways, the parties involved can align their programmes of work and methods to help capacitate their clients’ needs, facilitating more lean working processes throughout the procurement, design and construction stages.