Pressure Pulse Production of Train Passing to Adjacent Line

compact Pulse Production of Train Passing to Adjacent LineThis way out concerns the pressure neural impulse produced by one check into on other be passed on an adjacent line.Although studies of this phenomenon had been under taken for research and development purposes during the 1970s, a ask to quantify the magnitude of the effect for existing and future elevated zip service routes arose in the late 1980s due to adverse comments from convey users. The comments were relatively rare, provided generally centred around passengers being startled by the banging of doors (particularly of external sliding doors used on somewhat types of ninefold Unit) and windowpanes (particularly hopper windows) when passed by other trains at high speeds. In addition, deep brown and other drinks resting on tables on the side adjacent to the Fast line, mainly in other HSTs, were regularly spilt by passing HSTs. This was caused by a rapid displacement of the coach wall against which the table s rested.Although the events could not be called serious, it was straightforward that a criterion was needed for the design of new trains for thei) Door and window mounts and for the structural side-wall stiffness of vehicles likely to be operating on high speed routesii) Future high speed train nose shapes, (as it was cognise that it was the aerodynamic shaping, as well as speed, of the source train that size the pulse magnitude).Subsequently, interrogations were undertaken by the Research Division of BRB in 1988 to assess the magnitude of the largest pressure pulses produced by service trains at that time. Tests were undertaken on ECML with a test vehicle being passed, during two static and moving tests, by a number of service trains. Of particular interest was HST, as it was often the anger train and was operating at speeds up to 125 mi/h on insures at a nominal spacing of 3.4m. In some places, tether spacing was k right offn to be less than this and, of course, considerab ly more than than this in other places.In addition, the Class 91 loco was being produced and it was necessary to choose a criterion bearing in intelligence future operation of the IC225 train (also on ECML). In that event, it was decided during discussions amid the senior managements of the Research Division and the IC225 disgorge Team that IC225 operation at 225 km/h should form the limiting condition for defining the pulse limit. At that time, prior to tests being undertaken with Class 91, it had been assumed that the pulse characteristics generated by the nose shape of the Class 91 would be similar to HST, and so that a criterion based on an HST go away scaled up from 125 mi/h to 225 km/h (140mi/h) should be put one acrossed.Results from the tests produced a mean value, (taken over several passes at different booster cable spacings and speeds of both trains), for the HST normalised to 3.4 m nominal track interval, which was wedded by the non-dimensional parameter, CP = 0 .6. At 225 km/h, this equated to 1.44 kPa peak-to-peak amplitude.Subsequent tests with IC225 showed the Class 91 to have slightly better characteristics than HST, but the 1.44 kPa value was adopted for future project design purposes. An indication of this is given in the attached letter involving a proposed lC250 development for WCML operation scripted by the Technical Director (Research) of British Rail Research to the Project Director IC225.It is important to note that, in this letter and elsewhere, the 1.44 kPa criterion was specify in association with 3.4 m track spacing. Similarly, acceptance tests undertaken during development cause on new train designs were checked against a limit of 1.44 kPa at 3.4 m track spacing.Further, BR Research advised that, for practical purposes during track tests, compliance with the criterion was to be checked against a measurement taken at mid-window height on a stationary observing train on straight track on a calm (no wind) day. The result th en was to be corrected to nominal 3.4m track spacing.ObservationsIn the same way as for the original tests and for the nominal service condition elect by Research and DMEE management, there bequeath be circumstances now when 1.44 kPa is exceeded. For example, movement of the observing train, the presence of cross-winds, reduced track spacing and track curvature can all increase the pulse amplitude. Thus, it is important to adopt this spec of the reference set of conditions under which the criterion is to be met. office that the above implies that rolling stock operating on high speed routes should be structurally designed to a criterion in waste of l.44kPa for the train passing pressure pulse parapraxis. For the proof load case of unsealed trains, this will usually be covered by the Q.5kPa specification for vehicle body structures (see Railtrack Gp. Stds. GM/TT0l22, GM/TTOl23, GM/RC2504). Sealed trains will be covered by their own more stringent limits. However, bear load case s particularly for unsealed trains may need to incorporate high values associated with regular exceedances of the 1.44 kPa value.It would appear, therefore, that the original Railtrack Spec. for WCML mistakenly omitted reference to 3.4 m track spacing in its definition of the conditions under which the 1.44 kPa criterion should be met. Incidentally, the agree Railtrack Spec. for ECML does define 3.4 m as the reference condition.