HS2 Gauging – the Uniform Structure Gauge (USG)
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TECHNICAL ARTICLE AS PUBLISHED IN The PWI Journal January 2020 VOLUME 138 PART 1 #thepwi thepwi.org PermanentWayInstitution @PermWayInstit Permanent Way Institution @the_pwi If you would like to reproduce this article, please contact: Kerrie Illsley JOURNAL PRODUCTION EDITOR Permanent Way Institution [email protected] PLEASE NOTE: Every care is taken in the preparation of this publication, but the PWI cannot be held responsible for the claims of contributors nor for the accuracy of the contents, or any consequence thereof. HS2 Gauging – The Uniform Structure Gauge (USG) AUTHOR INTRODUCTION EXAMPLES OF TYPICAL AREAS WHERE GAUGING IS REQUIRED Gauging is an integral part of any railway Klaus Pajung system. This paper describes the HS2 approach Typically, gauging is required for the following Senior Permanent Way to gauging and it shows how HS2 established scenarios: Design Engineer 4 different Uniform Structure Gauges (USG) which suit their specific infrastructure. The paper CLEARANCES TO STRUCTURES AND Klaus is a Senior also provides an overview on how USGs are EQUIPMENT Permanent Way calculated. Design Engineer with The most common structures and equipment to an overall experience BACKGROUND stay clear of comprise: of 17 years. He is a Chartered Engineer in Germany (Diplom Every Railway Infrastructure manager has to 1. Overbridges (soffit and abutments) Ingenieur - FH). ensure that the type of rolling stock on their system can be run in a safe manner from a spatial 2. Tunnels including evacuation walkways Klaus came to the UK in 2005 and stayed perspective, ie the trains don’t hit parts of the and associated equipment (e.g. ventilation with Atkins in Birmingham for the following infrastructure or other trains. This is achieved fans, OLE, cable troughs etc.) 3 years. There he mainly worked on S&C by means of ‘Gauging’. For HS2 gauging the schemes at various design stages. TSI is applicable which refers to Euro Norms 3. Lineside equipment such as signals, (EN) to determine structure gauges for new and masts, posts, speed boards etc. Klaus then moved on to Halcrow in London interoperable infrastructure. who he is still with, (now Jacobs). There he 4. Platform offsets. Platforms are special worked on NR schemes at various GRIP In general, a structure gauge is an envelope structures, as trains have to pass them stages, TfL projects and international describing an area that must not be infringed by at a relatively close distance. This is projects. any infrastructure or lineside equipment under because of a ‘conflict of interest’ between any condition (see figure 8). structural clearances and appropriate He is currently seconded to HS2 where he stepping distances. A sufficient clearance is looking after the track alignment including Even though EN calculation methods for structure to the platform is essential and has to be the associated standard, the S&C geometry gauges are predetermined, the Infrastructure guaranteed for stopping and potentially standard and the gauging standard. manager has options to create different structure for fast, non-stopping trains. However, for gauges that suit their specific needs. For passenger friendly stepping distances, example, they might want to have a ‘Uniform trains need to be as close to the platform Structure Gauge’ (USG) which is applicable to as possible. specific areas such as tunnels, the open route, stations, station approaches, depots etc. TRACK SPACING AND PASSING CLEARANCES The following points will give the reader some general background on gauging. Track spacing is the distance between railway tracks. For NR, a standard spacing is 1970 mm WHAT IS GAUGING? between the running edges of the rails on straight track which equates to 3.405 m between track Gauging is the process for ensuring that trains centre lines (CL). For HS2, the track spacing, which are used on a specific section of track and measured from CL to CL, is dependent on the railway infrastructure are compatible in terms speed. This is because with increasing speeds, of spatial relationship. These days gauging is a aerodynamic considerations must be taken into scientific method which creates an artificial train consideration. HS2 uses track spacings which envelope that is greater than the physical train, are compliant with the TSI and which are similar taking into considerations items such as track to other European high-speed administrations. geometry and speed amongst others. Therefore, no analysis needs to be undertaken to prove these track spacings are sufficient. As the Independent of the gauging method used (see TSI only covers speeds of up to 350 km/h, a track further below), the resultant envelope determines spacing of 4.7 m has been specified by HS2 for the space that must not be infringed on by any speeds between 350 km/h and 400 km/h. This is part of the infrastructure or line side equipment. 0.2 m wider than the track spacing required by the The resultant envelope might be called Structure TSI for speeds > 350 km/h. HS2 appreciate the Gauge (eg in the EN) or the Swept Envelope fact that future improvements in aerodynamics in other standards. The latter usually requires might have to be achieved so the speed could be additional distances (clearances) to be kept to the raised to 400 km/h should this be implemented at envelope. some stage in the future. 34 FOULING POINTS HS2 GAUGING Fouling points (FP) are points between the HS2 have 4 USGs as described below. This is through track and the diverging tracks of a to avoid having a single and very large USG turnout or crossover arrangement beyond which would use worst-case input values from which trains would collide if both tracks were across the system. occupied at the same time. To establish the appropriate position of fouling points the On the one hand such a single structure gauge relevant structure gauge (Limit Gauge for EN would be user-friendly for the Infrastructure gauging) must be calculated. See Figure 1 as manager. On the other hand, an oversized an example. single structure gauge would mean that structures or lineside equipment would have GAUGING METHODS to be further away from the tracks, therefore potentially increasing footprint and cost. This is Figure 1: Fouling point as per Spanish gauging There are different gauging methods which are in particularly true for tunnels as with a single standard for through speeds >120 km/h. described as follows: route-wide USG the diameters of many tunnels would have to be increased. ABSOLUTE GAUGING This section provides some background Absolute gauging is mainly used on existing information and detail on various aspects of infrastructure. It is a full assessment of HS2 gauging. clearances on a section of existing track between the vehicle and fixed infrastructure USE OF THE SPANISH GAUGING and the vehicle and vehicles on adjacent STANDARD tracks. These days absolute gauging is executed by means of computer programmes HS2 gauging is based on the Spanish gauging like ClearRouteTM, DGauge etc. These standard (FOM/1630/2015) which is well programmes consider the whole suite of rolling established and has a proven record for high stock used on a section of track with all their speed railways. It is based on EN15273 and in characteristics (static envelope, suspension, fact, is a further development of the EN which bogie distance etc.). They also consider track ‘puts meat on the bone’ in sections where the Figure 2: Typical ClearRouteTM output for related properties (track form, curvature, cant, EN is rather vague. For example, EN15273- structure and passing clearances speed etc.) and wear, likely track movements 3 (section 5.5.3) provides two examples of etc. to calculate a swept envelope. This scenarios for the calculation of USGs which swept envelope is an enlarged version of the might be considered: static envelope and used by the software to determine clearances to the existing • The worst-case situation: Worst-case infrastructure. Most railway administrations input values are considered such as will define a clearance to the swept envelope smallest radius, the maximum cant or that has to be met. For example, NR define a cant deficiency etc, clearance of 100 mm to the Swept Envelope as ‘normal’ in many cases. Figure 2 is a typical • Defining of the gauge with two profiles: Table 1: HS2 Uniform Structure Gauges ClearRouteTM output showing structural and One profile applicable on a straight or passing clearances for a wide range of rolling curved track with very large radii and no stock. cant. Another profile on a curved track designed on the basis of the worst-case COMPARATIVE GAUGING cant and radius situation. Comparative gauging is the process of The Spanish gauging standard describes comparing the swept envelope of a new the second scenario in detail; considering 8 vehicle with the swept envelope of a vehicle or different scenarios as a result (see calculation vehicles which have demonstrated to comply section for more detail). with gauging requirements of a track section. This way conclusions can be drawn on whether The HS2 calculation methodology is based on this new vehicle can be used on a specific this second scenario. route section or not. TYPES OF GAUGES REQUIRED FOR HS2 DEFINED GAUGE METHOD AS PER EURO GAUGING NORM EN 15273 HS2 use the following types of gauges in their The defined gauge method described in EN standard: 15273 (Parts 1 and 3) is split into 3 main methods: • Uniform Structure Gauge (USG). The Figure 3: Overlay of area-wide USG (black) USG is used to determine the distances A) The static method is used for specific, non- and local USG (red) to be kept to between structures and interoperable networks. equipment and to the trains and therefore to the tracks. HS2 developed 4 different B) The dynamic method is used on certain USGs for different areas of application networks with the aim of optimising the space along the route These are summarised available for sizing non-interoperable vehicles.