Laura Lewis
Mott MacDonald
Laura Lewis is a Principal Human Factors Engineer and a Chartered Ergonomist and Human Factors Specialist. She has experience working across the transport sector including involvement in numerous projects within the rail industry. She has worked for clients such as RSSB, London Underground, Network Rail, Crossrail and rolling stock manufacturers, providing user insights to inform the design and development of rolling stock cabs and saloons, stations and signalling centres.
Technical Specifications for Interoperability (TSIs) from the European Railway Agency (ERA) call for ‘harmonised pictograms to be used to mark controls and indicators in the cab’ but do not specify which pictogram (or symbol) is applicable to which control in the cab environment. Industry stakeholders had raised concerns about the lack of guidance on the implementation of pictograms in future GB rolling stock cabs. The draft standard prEN 16186-2 and prEN 16186-3 provide standardised pictograms for some driving elements, but many controls and indicators currently in use in GB train cabs were not addressed. Therefore, to manage the gaps, rolling stock manufacturers had developed their own pictograms for labelling equipment, potentially leading to inconsistencies between train cabs. This, in turn, could result in:
- Mis-interpretation of pictograms as a result of labelling inconsistencies between train cabs
- Reduced interoperability of train drivers across the industry, and increased retraining costs when moving between rolling stock
- Duplication of pictogram development costs.
Mott MacDonald was commissioned by RSSB to develop an industry agreed set of standardised pictograms. The project comprised four phases:
- Review of existing and future cab controls and indications, and existing pictograms to identify gaps
- Application of usability design principles to evaluate the suitability of pictograms derived from sources other than standards
- Concept development of new pictograms to address the gaps
- Usability testing of the developed pictograms.
This paper presents the robust and repeatable methodology which was developed to design and test the pictograms, adapted from the methodology provided in ITL/GN0002, Guidelines for symbol design and testing (RSSB 2003). The approach was comprised of two main elements: development of pictograms and user testing.
A series of creative workshops with passenger and freight train drivers were conducted to develop concepts and ideas from which pictogram variants were developed.
The developed pictograms were tested with train drivers using an online questionnaire. The questionnaire was designed to assess the extent to which drivers understood the pictograms (comprehension test), the extent to which pictograms for different driving elements might be confused with one another (mutual confusion test) and which pictograms the drivers liked the best (preference selection test).
30 new pictograms which passed user testing were produced as a result of this process. A further 70 pictograms that were identified from train manufacturers or existing train cabs were assessed against usability criteria and were considered appropriate for future use in train cabs.
As a result of consultation with the GB representatives for the CEN/TC 256/SC 3/WG 37 for Driving Cabs as part of this project, the group has agreed to include the pictograms within EN 16186-3 Railway applications – Driver’s cab – Part 3: Design of displays.
The standardisation of these pictograms will increase consistency in new and refurbished rolling stock and therefore reduce the likelihood of errors of interpretation as well as the costs associated with pictogram development.
Ergonomics design in control facilities, train cabs and rolling stock , Human error and human reliability
