State of the literature

The research literature – papers on aspects of travel and transport in peer-reviewed journals – has burgeoned in recent years. There are more papers in established journals and new journals created, often on an open access basis whereby the researchers pay the cost of publication, rather than journals relying on Libraries taking out subscriptions. The commercial basis of these new open access journals is not always clear, but certainly some are operated by for-profit publishers. There may therefore be an incentive to relax standards in the peer-review process to generate more income, lessening the overall quality of the research literature, which accords with my subjective impression. Some of the not-for-profit open access journals appear to lack editorial oversight by academic researchers.

One feature of many recent publications is the theoretical modelling of a new technology. This may be useful where there is a clear practical need, for instance the optimal deployment of charging points for electric vehicles. Yet there is also extensive modelling activity in relation to the deployment of autonomous vehicles (AVs), where experience of on-road behaviour is extremely limited thus far. Because model outputs depend on assumptions about AV performance parameters, the conclusions of such studies are very varied and provide little in the way of useful guidance to practitioners and policy makers.

Another feature of the literature is the excessive formal analysis of survey findings, for instance of the responses to surveys of the expected impact of a new technology, such as AVs, whether of drivers or city planners. State of the art analysis is reported in tabular form, with statistical significance specified numerically. Rarely are findings reported as charts, bar charts or scatter diagrams, with uncertainty shown visually, which would make clear the common limited significance of the findings.

A further feature of the recent literature is the systematic review, in which formal search methodologies are employed to identify all relevant papers on a topic. One problem is that because of the deteriorating quality of the literature, it becomes difficult to see the wood for the trees, as every paper needs to be cited. Systematic review originated in the medical literature where the aim of such meta-analysis is to identify every relevant study of a condition or treatment, with a ranking by quality such that only the highest quality papers contribute to the conclusions of the review. But for transport studies, such quality ranking is not practical, in part because findings may be specific to particular locations or circumstances.

Another problem with formal searching of the literature is that relevant papers may be missed because of the difficulty of specifying appropriate search terms. A recent paper by a distinguished transport researcher addressed a topic on which I had published some years ago without mentioning my contribution. When I raised the matter, I received an apology that his search had failed to identify my papers.

I have noticed increasing reference in the recent literature to transport researchers as ‘scholars’, a term hitherto largely reserved for those working in the humanities. Generally, those involved in transport research have seen themselves as based in disciplines such as engineering, economics, planning and the environmental sciences. The purpose of research within such disciplinary frameworks has been to advance understanding and thereby contribute to practical solutions to the problems of the transport sector. We have not, I think, seen ourselves as primarily involved in developing a branch of knowledge through scholarship that focuses on the extant literature. Indeed, the inward-looking processes of scholarship are cluttering up the literature with findings of little use and thereby may be displacing contributions of more practical value.

For instance, I have been attempting, without success, to get published in a peer-reviewed journal a paper on Digital Navigation, by which I mean the combination of satnav, digital mapping and route guidance algorithms that are in widespread use by road users. Highways Magazine, read by practitioners, has published a short account of my analysis, but a fully documented paper seems not to fit the current fashion for what’s hot, as seen by journal editors.