The current system fitted on the Chiltern Lines is SELCAB ATP and provides trains with continuous protection against a SPAD and/or over speed event. The existing train borne ATP equipment and lineside transmitters are now deemed as obsolete and suffering from repeated failures; therefore long-term ATP operation cannot be sustained and requires replacement. The proposed change from the current ATP system is to fit the Chiltern Lines with Enhanced TPWS (Train Protection Warning System), providing speed monitoring on the approach to all signals set to danger and a number of critical permanent speed restrictions. TPWS is designed to initiate a brake application if a train passes a stop aspect, is approaching a stop aspect at excessive speed or at other high-risk locations e.g. on the approach to a permanent speed restriction or buffer stop. As the current ATP system provides continuous protection, the Chiltern route has decided to provide 'Enhanced TPWS' with provision going over and above that detailed in the industry fitment standards. A total of 3 junction speed restrictions and 158 signals are impacted by the works, with varying levels of complexity.
BWB have provided competent resource to undertake the role of Signalling Design Contractor's Responsible Engineer (CRE), as defined in Network Rail Standard NR/L2/RSE/02009 - Engineering Management for Projects, on behalf of the client company throughout GRIP Stages 5 to 8. The BWB CRE has been accountable for the whole signalling detailed design process, including competency assessments and compliance of the design outputs. The delivery was made more complex by design activities being shared between three companies, VRSB, Wabtec UK & Mott MacDonald and a requirement to complete all installation activities by Easter 2023. This introduced the need for a progressive delivery approach, with the project split into 10 separate geographical areas with each design completed/approved separately. This allowed construction to start on the first section while design was progressed for the next. Design approval is now being completed collaboratively with Network Rail through the self-assurance process. This was approved after confidence had been gained from the initial design submission and BWB's Signalling CRE was provided with delegated authority to approve design submissions on behalf of the Network Rail DPE.