<center>Figure 8: Semi-systematic literature review, [34] </center>
The first steps of the review resulted in various results, detailed in execution and interim findings as follows.
Explicit searches were run to report the overall range and depth of literature in this top- level field. This was completed using Web of Science [WOS]4, Google Scholar [GS], the EU Transport Research and Innovation Monitoring and Information System [TRIMIS5], EUR- LEX and the Addleshaw Goddard databases.
A large proportion of non- peer- reviewed literature existed in this field, often from research projects in the form of reports and other deliverables. Bryman called this 'grey' literature - of great value in many fields of research into people and systems. To enable a semi- systematic review of such materials, we utilised research outputs catalogued within the NOVELOG toolkit6 [35]. Since research and innovation projects and