Developing an evaluation framework for screen doors on railway platforms

Abdurrahman, Usman Tasiu ORCID: 0000-0002-3565-478X (2021). Developing an evaluation framework for screen doors on railway platforms. University of Birmingham. Ph.D.

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Abstract

Platform Screen Doors (PSDs) are physical barriers installed at the edges of platforms in train stations. Such doors are widely used in modern metro stations and some heavy rail stations despite the installation cost being high. The decisions for installing these doors are made for different reasons in different systems, often without a full consideration of the relevant factors. In this thesis, there is a brief discussion around safety decision making in railway and other industries, but the main feature of this research is around the breadth of factors that can be taken into account in a conventional CostBenefit Analysis (CBA).

The author compiles a comprehensive list of factors associated with PSDs and develops a model to support issue identification and decision-making by project sponsors. He highlights the state-of-the-art deployment situation of PSDs and draws evidence from prominent railway systems. This thesis identifies 85 railway operations and technical factors which are affected by PSDs; compiled from sources including relevant literature, consultation with industry experts and through adoption of systems thinking. The factors are brought together to produce a system dynamics model identifying causality between the factors and succeeding variables. The factors are then quantified in their respective units using mathematical equations developed through this research, and converted into a common unit of currency. These values are incorporated into an executable spreadsheet model developed for the purpose of carrying out an economic analysis to reveal the overall gain or loss (in terms of benefits and disbenefits) associated with PSD deployment.

The model, which serves as a decision-making support tool, can be used on different rail networks to help decision makers make informed decisions when considering the deployment of PSDs. The methodology of this thesis can serve as a framework for systems engineers and can be used for other elements of a system, whereas the iimodels produced provide consultants, contractors and suppliers of PSDs with a comprehensive checklist that would be useful for any PSD case irrespective of the network characteristics.

To test the executable model, a case study was developed using a hypothetical station formed from a combination of real data secured from different rail systems in different continents. The data was aggregated in such a manner that stakeholder confidentiality of data is preserved. The blended real data is used to form default values in the model that can be used in cases where local data is unavailable, for example in the case of new-build platforms. Variations in local factors, e.g., the value of avoiding a fatality, cost of equipment etc., mean that it will always be recommended that the model is used to undertake a specific local evaluation both for new-build and retrofit cases. The results obtained using default values for a specimen station yielded an overall benefit of nearly £11.5 million, overall disbenefit of £11.8 million, Net Present Value (NPV) of -£271,461 and Benefit–Cost Ratio (BCR) of 0.98. This is calculated over a 35-year lifetime for the PSDs. Even though different organisations may have different BCR requirements or rules of thumb, the 0.98 BCR means that the benefits derived are just less than the disbenefits/costs involved. However, sensitivity analysis shows that small changes in input variables can change the BCR significantly, either up or down. From this generic analysis the we can reach two preliminary findings – that benefits and costs can be broadly in balance, and that it is essential that local parameters are used to support any decisions to implement or not to implement PSDs.

The high-level factors influencing the results include the value of a fatality avoided, safety (including suicides) having the greatest impact and amounting to nearly £7 million over the PSD lifetime. This is followed by energy consumption, for which a benefit of £4.3 million was determined. On the negative side, the effect on capacity leads, with a loss of £5.6 million, followed by the cost of PSD equipment that ranges from £13,000 to £18,000 per linear metre.

Application of the Pareto principle when evaluating the economics for one platform to a station, line or network suggests a strategic analysis and selecting only those platforms/stations with critical requirements to be fitted with PSDs. This makes the calculation much more feasible for PSD installation on those critical platforms.

The thesis therefore presents a comprehensive approach to evaluating situations, identifying relevant factors, quantifying them and coming up with evidence-based information that serves as a decision-making support mechanism which helps decision makers to make informed, scientifically based, decisions. Even though the case study presented in the thesis is around the deployment of PSDs, the framework developed can be customised to suit other scenarios for which scientifically based decision-making is required.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):