Transitions of transport systems are necessary to meet climate targets and reach sustainable development goals. Sustainable transport needs to be equitable, efficient, safe, and green. Transport systems need to become less resource-intensive, whereby sharing and utilising resources more efficiently can be a route forward. However, for well-functioning sharing, the involved stakeholders need to collaborate. Thus, sharing resources can mean sharing material and physical resources, such as vehicles and places, but it can also mean sharing immaterial and intangible resources, such as time and responsibilities. Through an interview study exploring shared resources in goods deliveries at off-peak hours in Stockholm-based trials, opportunities for organising transport system innovations have been investigated. Interviews were carried out with thirteen respondents involved in, or related to, off-peak logistics, and trigger materials were used to deepen the conversation when discussing the logistics service systems. Off-peak trials can be seen as innovation processes affected by several conditions. Innovation processes are collaborative, and collaborative innovation involves decision-making coordination across organisational boundaries. The concepts of sensemaking and sensegiving are used to analyse the studied collaborative innovation processes. However, stakeholders engaged in innovating sustainable transport systems must find new ways to collaborate, as ambiguity and uncertainty are more extensive than in their day-to-day business development or the incremental development of new services. This study shows that conditions for such collaborative innovation processes vary between different types of collaborative settings, as innovation depends on the transformative capacity to alter types of stakeholder agreements and roles and agree on how to share resources and design such sharing. Designing for resource sharing requires understanding how to design tangible and intangible buffers, and for the involved stakeholders to make sense of such new designs.