0 Rail Safety and Standards Board

Transcription

1 0 Rail Safety and Standards Board Certificate of Derogation from a Railway Group Standard (in accordance with the Railway Group Standards Code) Derogation London North Eastern Network Rail Technical Contact :- C/O [name removed], 3 rd Floor, Desk 22, 40 Melton Street, London NW1 2EE Licensed Infrastructure Operator Automatic Warning System (Tracker No 4733) 5a. Details of Railway Group Standard (RGS): RGS Number: Issue No: Issue Date: Title: GE/RT8035 One October 2001 Automatic Warning System (AWS) B6.2.b) B6.2 AWS for movements from unfitted lines to fitted lines In the special case of signals controlling movements from running lines that are not fitted with AWS track equipment to a running line that is fitted, the following arrangements apply (see diagrams 4 and 5 in Appendix D): b) Where the running line not fitted with AWS leads only to an AWS fitted line (ie the two lines converge), the stop signal controlling movements from the unfitted line to the fitted line and the associated distant signal shall both be fitted with AWS track equipment in accordance with the requirements of clauses B6.1.1 B6.1.4.

2 Three boundaries are included:- " Access from CTRL (Section 2) to Camden Road approaching CR1117 signal. " Access from St Pancras International to ECML approaching K259 signal. " Access from St Pancras International to Camden Road approaching CR1119 Signal. See attached sketch of the St Pancras area giving AWS locations, lineside signs and KVB beacons. The standard requires that, where a non AWS fitted line merges with a fitted line, the stop signal controlling movements onto the fitted line and its distant signal(s) are fitted with AWS. The purpose of this requirement is understood to be to ensure that the AWS system 'on the train' is operational and, by providing a warning at the distant signal, control the risk of SPAD onto the fitted line. At the boundaries between CTRL managed infrastructure and Network Rail managed infrastructure in the St Pancras area, the distant signals are not provided with AWS since these signals are controlled by CTRL and within a CTRL designated AWS gap area. The removal of AWS was accepted by the CTRL SRP with the support of Eurostar and Southeastern. The new CTRL St Pancras terminal station and approaches is fitted with colour light signalling. In addition, the continuous supervision KVB Automatic Train Protection (ATP) system is installed to comply with CTRL requirements for full ATP. As a consequence, CTRL signals leading to the NR interface on the North London Incline are not fitted with AWS and are therefore not compliant with GE/RT8035 clause B6.2.b). The final signal leading to the fitted line is controlled by Network Rail and is fitted with AWS on the approach. The AWS gap within CTRL controlled infrastructure has been agreed by CTRL SRP due to other measures in place. All trains operating in the AWS gap area are required to have the KVB train protection system fitted and CTRL SRP have deemed that the system satisfies the requirements for non-provision of AWS on CTRL infrastructure. The speed of approach to each of the stop signals is low (25mph max) and this is enforced at the distant signal(s) by the KVB system. Additionally, TPWS is provided at the stop signals and this has been designed to be fully effective at controlling overruns. An alternative practice of proving the AWS operational is being put in place, as GE/RT8035 clause B6.2 does not take into account the issues involved with transitions between different train control systems and different infrastructure controllers, or the specific constraints imposed by the infrastructure arrangements at each interface area. To achieve compliance would mean the addition of AWS to the NR interface signals at St Pancras and this would complicate the ergonomics of the train protection system, with some signals fitted with AWS and KVB and some signals with KVB only. This could cause confusion and a likely reduction in overall safety. The CTRL St Pancras station has 3 interfaces to the adjacent NR North London Incline via Silo Curve (signal CR1119), ECML Connection (signal K259) and NLL Connection (signal CR1117). The Silo Curve and ECML Connection are approached by trains leaving St Pancras station. The NLL Connection is approached by trains leaving the CTRL high speed line. Trains leaving St Pancras station bound for NR infrastructure (either via the Silo Curve or ECML Connection) will have the cab configured for operation in BR AC mode. This switches on the AWS and TPWS and performs a self-test of both systems. This proves the system operational before entering NR infrastructure, which is 2 or 3 short signal sections away (between 600 and 800 metres approximately). Trains leaving the high speed line bound for NR infrastructure (via the NLL Connection) will have the AWS/TPWS switched on and proved operational during the changeover between TVM430 cab signalling and lineside signalling. This proves the system operational before entering NR infrastructure, which is again 2 short signal sections away (700 metres approximately). As a further current mitigation, all trains must stop at signal CR1117 on the NLL Connection, which is the first NR signal. While stopped at this signal, the driver must change the cab configuration from BR HSL to BR AC mode. This again switches on the AWS and TPWS and performs a self-test of both systems.

3 However, this is only procedural and not a requirement of the signalling system, and may be subject to future procedural change. Lineside signage has been located at each interface to remind the driver he is entering an AWS fitted area and appropriate signs are provided for the traction configuration changeover at CR1117 on the NLL Connection. In addition, operational instructions will be provided for each changeover. The severity/degree of the proposed non-compliance is small, as the requirement to prove the AWS operational is being met in an alternative way that is more effective and appropriate to the changeover of train protection systems involved, as well as meeting the requirements of GK/RT0036, Transition Between Lineside Signalling Systems and Other Systems of Train Control (clause 4.4.3).In addition, a non-compliance pending Railway Group Standards Revision (number 02/222/NC) on the related issue of trainborne AWS has already been accepted. It is proposed that GE/RT8035 be revised to refer to GK/RT0036 when AWS is involved in a transition between different systems of train control. CTRL SRP have decided that KVB is an adequate system to justify an AWS gap and that the risks of distraction to drivers are sufficient that AWS will not be provided on CTRL infrastructure. With the low speeds (enforced by KVB), the two caution aspects and AWS at the stop signal, it is considered very unlikely that a driver will reach the stop signal unaware of the need to stop. In the event that a SPAD occurs, the TPWS at each location is effective in controlling trains to a stand within the available overrun. Any trains approaching the interface will have AWS equipment and, due to the AWS enabling or cab setup, the AWS will be displaying the warning indication. Achieving compliance by providing AWS only for the NR interfaces at St Pancras would introduce additional risks as it could complicate the changeover process and provide a distraction to the driver. Only a short area of closely spaced signals (between 200 and 400 metre signal spacing approximately) is provided in the CTRL St Pancras area. The sighting on signals is continuous, and the infrastructure is complex with many driver tasks required on the changeover between CTRL and NR, including changes of traction and radio systems as well as train protection system. Keeping a clear boundary between train control systems is part of GK/RT0036 and adding AWS could confuse the issue. In addition, any train operator wishing to use the interface between CTRL and NR at St Pancras will have to provide safety justification to show that the train systems provided comply with the safety requirements of the interface. The risks are controlled by the low speed of approach (KVB enforced), TPWS on the stop signal (which is effective) and two cautionary aspects (4 aspect signalling). The risk being controlled by GE/RT8035 clause B6.2.b) is of a train entering a line fitted with AWS with the AWS not being proved operational and, consequently, a train driver will have no audible warning of the signal aspect being approached or visual cab reminder of whether the previous signal aspect was cautionary or not, which could increase the risk of a SPAD. Additionally, there will not be the fail safe protection of the train brakes being applied if the driver fails to acknowledge the AWS warning. It is to mitigate against these risks that clause B6.2.b) requires an AWS magnet to be associated to the signal controlling entry to the fitted line to ensure the AWS is tested before entering the fitted area. However, this method relies on the driver noticing he has not been given an AWS indication and realising the AWS is faulty just prior to reaching the AWS fitted line. The alternative measure provided at St Pancras involves the AWS and TPWS being tested directly before entering NR infrastructure as part of the driver set up or traction changeover procedures. This is an inherently safer method than that proposed by GE/RT8035 clause B6.2.b) as this controls the risk of the driver failing to notice an AWS indication has not been given. In addition, the use of the KVB system mitigates the risk of SPAD, as the train speed is controlled down to 30 km/h on the approach to the first NR signal at danger (15 km/h if reduced overlap). KVB beacons are located just prior to the first NR signal and switch off the KVB protection before the TPWS loop is reached (see note below). Consequently, the TPWS trainstop loop is in accordance with NR rules and can be demonstrated to be effective at all valid approach speeds.

4 Note: The KVB system gives only limited information to the driver as the purpose is for train protection, not cab signalling. The KVB acts as a standard ATP system with similar functionality to ERTMS level 1. The on-board computer calculates a braking curve (based on signal aspect, gradient, distance). If the driver's speed exceeds that calculated on the braking curve by 5 km/h, then a warning sound and flashing yellow light is displayed. If the driver's speed exceeds that calculated on the braking curve by 10 km/h, then the emergency braking stops the train. The train speed is monitored down to 30 km/h at a point on the approach to the signal (with a warning at 35 km/h and an intervention at 40 km/h). This speed is called the release speed and allows the driver to pass a signal if it clears from red after the train has passed the last beacon. If a train passes a signal at red at the 40 km/h release speed, then the KVB trainstop beacon at the signal will trigger emergency braking and stop the train in the 120 m overlap distance needed by the KVB system. If an overlap of less than 50 m is required, then another beacon (termed a prox beacon) is placed 125 m before the signal. This beacon changes the release speed to 10 km/h (with a warning at 12.5 km/h and an intervention at 15 km/h). Therefore, the driver only gets one operational display, a 000 on the KVB panel when passing a prox beacon. This tells the driver he has to approach the signal at a reduced release speed of 10 km/h as the signal has a reduced overlap available. The only other displays are the KVB fault displays (trackside or trainborne), and, unless these are given, the driver assumes the KVB is operational. When the KVB protection is switched off, the onboard computer is instructed that it is exiting the KVB fitted area and the train speed is no longer monitored, but the system remains live and searching for a beacon at the start of the next fitted area. Clarification is sought as to whether a derogation is required where the distant signal(s) are either within an AWS gap or on a third parties administration, and if it is considered a derogation is necessary then it is requested for "non-provision of AWS at distant signal(s) on the approach to the stop signal controlling access to an AWS fitted line from an unfitted line. Network Rail have no jurisdiction over the CTRL controlled signals and hence cannot insist that they are fitted with AWS providing CTRL demonstrate that adequate measures are in place to control the risk of not providing it at the interface. Various risk assessments have been undertaken and each interface examined to ensure that any risks associated with non-provision of AWS on the distant signal(s) is ALARP. These take account of the fact that trains approaching Network rail direct from CTRL have an alternative method of proving the AWS operational at the cab to lineside transition. Achieving compliance would introduce safety concerns associated with driver workload which was part of the justification for creation of the AWS gap on CTRL.

5 Upon receipt, the applicant is required to identify affected, interfacing parties and copy this certificate, together with supporting information, to those parties. Applicant s Ref. Tracker No Head of Signal Engineering 09/05/2007 GE/RT8035 is currently on the list of NNTRs under the Locomotives and Passenger Carriages Conventional Rail TSIs, Control Command and Signalling TSI (for both Conventional and High Speed). Name of Committee: Date of meeting Minute reference: Control Command and Signalling 19/07/ /CCS/07/192 Signed by Jeff Allan on 24/08/2007 Jeff Allan Head of Delivery, Control Command & Signalling, and Energy 24/08/2007