The Professional Two-Monthly Magazine Of Rail Transport Worldwide

Volume 16 No. 3/16

Rail Tec Arsenal OffprintStandardised Functional Tests In The RTA Climatic Wind TunnelFunctional Testing For DifferentClimates Of Various Subsystems

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The new Technical ReportCEN/TR 16251: 2016 02 „Rail-way applications - Environmental con-ditions - Design guidance for rollingstock“ contains design recommenda-tions and test procedures for rail vehi-cles and components under definedoperating and environmental condi-tions. The Vienna Climatic Wind Tunneloperated by Rail Tec Arsenal (RTA) pro-vides an unique opportunity for carryingout these tests under standardised and reproducible conditions. A power-ful wind turbine, spray and sprinkler in-stallations and snow nozzles areavailable to investigate the impact ofextreme temperatures, rain, snowand ice on rail vehicles, compo-nents and systems (see photos 1and 2).

Functional Testing For Different Climates

The standard EN 50125-1 „Envi-ronmental conditions for equipment -Part 1: Equipment on board rollingstock“ defines specific environmentalparameters such as temperature, re-lative humidity, wind speed, solar ra-diation, rain etc. for different climatezones. However, it lacks provisions fortypical scenarios, which usually resultfrom the interaction of several individualparameters during in-service operation. Both operating and climatic conditionsmust therefore be simulated simultane-ously in order to identify potential prob-lems in advance. Experience has alsoshown that testing components withinthe vehicle is essential, since even thebest inspection cannot exclude the po-tential mutual interference betweencomponents and systems which mayoccur in regular service.

RTA has longstanding expertisein customer-specific functional testsunder different climatic conditions andhas systematically collected relevantdata about the susceptibility of individualcomponents and systems from railwayoperators and the rail vehicle industry.This information has provided the basisfor developing customised test proce-dures for critical scenarios and operat-ing modes, which are now beingapplied as „standard test procedures“in the Vienna Climatic Wind Tunnel. Themajority of these „standard test proce-dures“ have been included in the newCEN/TR 16251.

Ongoing innovation and progress inthe sector require these test proce-dures to be continuously adapted tonew functionalities or operating con-ditions and new test procedures to bedeveloped.

The table below right lists the testedsystems/components along with therelevant climatic test conditions as defined in CEN/TR 16251. The list alsocontains additional, more recent cli-matic test conditions and systems/components which have not (yet) beenincluded in the CEN/TR 16251. As canbe seen from the table, different cli-matic conditions are relevant for dif-ferent components/systems:- extreme temperatures and humidity

levels have a negative impact on mechanical, electrical, electronic andpneumatic components,

- the ingress of rain and wind, notablyvia the connecting corridors, doorsand windows, gives an indication ofleakage; proper functioning of thewindscreen wipers is also essential,

- wet snow has an impact on all me-chanical components exposed to out-side conditions, such as doors, steps,couplings and roof equipment,

- ingress of dry snow into air intakesand gaskets often leads to problems,

- ice formation on mechanical compo-nents, such as the pantograph, doors,steps and couplers may cause mal-functioning or blocking of the subsys-tem.

Vehicle

The thermal insulation and (vapour)tightness of the vehicle body is essen-tial for both passenger comfort andproper functioning of components andsystems. Insufficient insulation and/orleaks in the vehicle body often have a negative impact on interior tempera-tures and may cause condensate toform in the passenger areas or drivingcab. This may cause the floor surfacetemperatures in the vestibules to fallbelow freezing point at low outside tem-peratures, leading to ice formation. It istherefore important to check the properfunctioning of the whole vehicle in dif-ferent scenarios.

A typical test which is also in-cluded in CEN/TR 16251 involveschecking the functionality of the entirevehicle following sudden changes in cli-matic conditions, as for example expe-rienced by a train travelling throughwarm humid tunnels in winter. For thistest, the vehicle is soaked at tempera-tures lower than -10 °C for a minimumof 5 h with all systems in operation. Thevehicle is then shunted to an environ-ment with temperatures greater than+20 °C and a dew point greater than+15 °C.

After more than 10 min of operation,the condensation effects on the win-dows and signal lights (visibility) are

checked. Following the functional test,the vehicle is again returned to the winter environment (temperatures lowerthan -10 °C). After a minimum of 1 h,

the proper functioning of all relevantcomponents is checked. If required,the test can be repeated several timesto demonstrate freeze/thaw capability.

Safe and reliable operation of mainline rolling stock under all weather conditions isan essential prerequisite for enhancing passenger safety and comfort and thus increasingthe attractiveness and acceptance of rail travel. Standardised tests under critical weatherconditions can make a valuable contribution to reducing the risk of malfunctions aswell as improving vehicle reliability.

Table: Overview of functional tests of different components under specifiedclimatic conditions.

Photo 1: Vehicle prepared with ice layer for function tests (testing of Tram-Train Karlsruhe).

Photo: Bombardier

Standardised Functional Tests In The Vienna Climatic Wind Tunnel

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Subsystems

Bogie Components

Bogie components such as the axleand gear box, suspension compo-nents, sanding, level control, tilting andflange lubrication systems are safetyrelevant components that should neverfail under any circumstances. Thesecomponents are very exposed to out-side conditions and are thus extremelyprone to the accumulation of snow andice. The consequences of ice or snowbuild-up may range from partial mal-function to complete failure, as in thecase of ice formation on the sandingsystem, which is decisive for properfriction between wheel and rail.

All winter conditions with a negativeimpact on underframe components canbe realistically simulated on the dyna-mometer in a climatic wind tunnel. Thetests help both in developing mea-sures to reduce the problems, suchas fitting a heater or housing to thesanding system, and for validatingtheir effectiveness (see photo 3).

Brakes

Brake tests according to CEN/TR 16251 include the general func-tions of brake engagement and releasein ice conditions as well as extendedbraking distances due to snow condi-tions. Depending on the vehicle to betested, however, it will be necessary to

define specific test requirements (acceptable braking distance, brakingspeed, etc.) or apply other standards.

For example, the requirements forwinter approval of brake blocks (e. g.new low-noise composites for retrofittingbrake freight waggons) are defined inUIC Leaflet 541-4. Together withUIC experts, RTA has developed an ap-propriate test programme and is nowauthorised to carry out winter certifica-tion tests for these components. Thetests involve mounting the entire bogieof the freight waggon on the dyna-mometer and testing the braking per-formance at velocities of 100 km/h and120 km/h at a temperature of -10 °C.

Once the specified velocity isachieved, emergency braking is acti-vated and the braking distance is meas-ured. The braking tests are performedfive times for each velocity under dryconditions and subsequently five timesunder snow conditions. The results canthen be used to determine the meanbraking distance. The big advantage ofthis test procedure is that the wholebrake system, including wheel-railcontact, can be tested under repro-ducible conditions in a plannedtimeframe of three days without theneed for track tests (see photos 4).

Automatic Couplings

Winter conditions also pose a chal-lenge to the coupling mechanism, which

provides a mechanical and electricalconnection between rail vehicles. Fol-lowing reference tests in „dry“ condi-tions, the coupling is covered with iceat -20 °C to simulate freezing rain on theparked vehicle and with wet snow at -7 °C to simulate the front coupling ofthe running vehicle during heavy snow-fall. Tests with dry snow at -20 °C arealso included to simulate the snow en-trained from the track, which is com-pressed during the coupling processand accumulates on the rear coupling.

The subsequent coupling tests re-veal whether mechanical, electrical andpneumatic coupling and uncouplinghas been successful and whether thecoupling heater ensures proper de-icing of the coupling face. A visual in-spection is carried out to check if theautomatic opening of the protec-tive caps has led to snow and wateringress, which may allow moistureto get into the electrical contacts,resulting in a risk of short circuiting(see photo 5).

Photo 2: Water tightness test of roof components.

Photo 3: Winter testing of bogie components.

Photo 5: Testing the effectiveness of the coupling heater under snow con-ditions.

Photos 4: Test setup with freight waggon for brake block winter certifica-tion tests.

Photo: Siemens

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View Ahead

Driver visibility is of key importancefor safe train operation. Inadequatelyfunctioning windscreen heaters or airinlets in the driving cab may cause thewindscreen and/or side windows tomist up. Visibility may also be impairedby snow and ice build-up on the wind-screen, which may restrict or even pre-vent operation of the wiper blade.

One possible reason for these prob-lems may be poor adjustment betweenthe windscreen washer, wiper and heat-ing systems and the air conditioning unitof the driving cab. Climatic tests makeit possible to adjust the settings ofthese components under differentclimatic conditions and thus helpeliminate visibility problems underextreme service conditions (seephotos 6).

Doors And Movable Steps

Accumulations of ice and snow inthe door area obstruct or even preventopening, closing or automatic reversalof doors and may cause retractable stepsto become stuck.

Some targeted design modificationsor improvements in the control systemare often sufficient to eliminate theseproblems. In a climatic wind tunnelthese measures can be investigated

and tested efficiently under repro-ducible snow and ice conditions(see photos 7). As the malfunction ofdoors and steps is one of the most fre-quent problems reported by railway operators, two test procedures willbe described in more detail:

1) The door icing tests are carriedout at ambient temperatures of -20 °Csimulating a parked vehicle over-night. The passenger areas are coldand the air conditioning unit is switchedoff. The vehicle doors are covered withan ice layer of about 2 mm using a manualsprinkler. Once the last water film hasbeen applied, the ice is allowed toharden for 10 minutes. This procedureis designed to simulate freezing rain.The following pass criteria should beachieved:- the doors open and close completely,- the entrapment protection device

detects the test piece and the doorreverses, or the test piece can bewithdrawn with a force ≤ 150 N,

- the emergency unlocking system isfully functional,

- no snow (water, ice) ingress behindthe door.

2) The movable step test under wetsnow conditions is carried out with thepassenger areas in regulated mode,simulating regular service. A wetsnow layer of approx. 2 cm is applied tothe extended step using mobile snow

nozzles. The snow layer is compactedby foot and the step is subsequently re-tracted. The vehicle is then switched todriving mode, which causes the snowto cool down and turn to ice.

This procedure is designed to sim-ulate a normal drive cycle where thestep is extended, stepped on by pas-sengers and subsequently retracted.The snow from passengers’ shoes maycause ice build-up on the step and thestep enclosure, resulting in potentialmalfunction. This effect can be furtherenhanced by alternating climate tests,where the vehicle is moved to anotherenvironment (+10 °C) to simulate par-tial thawing during a station stop. Thefollowing pass criteria should beachieved:- the step extends and retracts com-

pletely,- the step detects obstacles and re-

verses; peak force on contact isbelow 300 N,

- the step does not move when the dooris fully opened.

Conclusions

The functional tests describedabove are only some examples of thecomprehensive set of standardised testprocedures available for different com-ponents and systems. Each procedureincludes a detailed description of the test

Photos 6: Defrosting of wind screen for driver visibility (testing of a DB’s Class 407 Velaro high speed train).

Photos 7: Movable door step with snow and ice build-up on a step.

Photo: Siemens Photo: Siemens

conditions and assessment methodsused to verify whether the specifiedcompliance criteria have been met. Thetests and functional requirements laiddown in these procedures have beenadapted to real-world conditions basedon many years of experience in climaticwind tunnel testing and feedback fromregular service operation. They ensurea high degree of comparability, provid-ing a sound basis for further standardi-sation of functional tests on rail vehiclesat an European level.

Functional tests in a climatic windtunnel make a substantial contributionto reducing the risk of failure in serviceand increasing the reliability of rail ve-hicles in all weather conditions. Thebiggest advantage of climatic wind tun-nel tests is that the climatic conditionscan be reproduced with great accu-racy. This helps to immediately verifythe effects of improvements and modi-fications, thus saving time and money.

Florian Knöbl, Matthias MayerProject EngineersRail Tec Arsenal

Gabriel HallerTechnical DirectorRail Tec Arsenal

Photos unless cited:Rail Tec Arsenal

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