Provisions of the UK National Annex for EN 1991-2 for Rail Bridges

BS EN 1991-2 defines models of traffic loads for the design of bridges including railway bridges. Where National Choice is permitted in BS EN 1991-2, the national decisions are presented in the UK National Annex for BS EN 1991-2. Where existing practice based on BS5400-2 is still relevant, this has been perpetuated, an example being the loading required for traction and braking. In some cases, loading requirements are not dealt with in detail in BS EN 1991-2 but the option is given to provide additional requirements in its National Annex. In many cases, the National Annex allows such issues to be dealt with on a project specific basis. Examples include the design of deck plates and local elements to resist derailment actions from rail traffic. BS EN 1991-2 also introduces a number of areas of railway bridge design that were not previously covered in BS 5400-2. These include the introduction of a factor (_) to account for railway loads greater or less than load model LM71 (equivalent to RU), groups of loads that represent the vertical loads with secondary horizontal loads as a single action, the introduction of a High Speed Load Model (HSLM) for railway vehicles travelling at speeds in excess of 200km/h and the requirement to check the combined response of the structure and track.

This paper describes the alterative load models defined in the UK National Annex to BS EN 1991-2 and the values and approaches to be used where new concepts have been defined in BS EN 1991-2.