Rail track inspection on new trailsAn economical alternative

Ultrasonic rail track inspectionsfor hidden internal defects arepresently done by track inspec-tion trains (SPZ) or trackinspection equipment (SPG).The SPZ are capable to inspectthe tracks at a speed of 40-80km/h. The SPG guided manual-ly by an operator permits theinspection of about 5 km trackwithin one working day. TheSPG is therefore used mainlyfor the inspection of switches,singel rails, rail welds an to pindown defects precisely. TheSPG is also employed for tracksections which could not bedone by the SPZ because ofspecial circumstances, e.g.because of technical problemsor in special cases or shorttrack sections. All these taskscan now be handled by a trackinspection vehicle (SPF) for thefirst time in Europe.The SPF of pethoplan gmbh isa HI-RAIL vehicle (for highwayand railroad) combining theadvantages of the train SPZwith the flexibility of the equip-ment (SPG), thus closes a longexisting gap in destruction-freerail track inspection.

The vehicle

The vehicle basis is a UNIMOGU 400 with trunk by the compa-ny ZWEIWEG. The track guidesystem ZW 110, also by ZWEI-WEG, has proven successfullyalready several times and wastherefore also chosen for theSPF.The vehicle is 7.33 m long andhas a gross weight of 12 metrictons.As customary for ZWEIWEG,the driver´s cab and the trunkare seperate from each other.The cab has three seats: All thedriving controls are handledfrom the driver´s seat. All

instruments necessary for thepositioning during the inspec-tion ride are arranged on thepassenger´s side. The vehicleis equipped with INDUSI, ver-sion 65R BZP 90 as well asSIFA and MESA 22. All custo-mary means of remote trackcircuitry are accessible.Approbation by TÜV, theRailroad Federal Agency andalso the operation permit asheavy auxiliary vehicle by theDB acc. to guideline 931ff areat hand.For road traffic the UNIMOGU400 has an operation permitfor up to 80 km/h.Driving on tracks the road drivewheels are used. Travelling ontracks the steering axle islocked and the track guidewheel system ZW 110 guidesthe vehicle. On tracks the per-mitted top speed is 50 km/h inboth directions because of thereversible eight-gear transmis-sion. While driving in reversethe driver sees the signalsthrough a true-color videocamera, mounted at the backside of the trunk. This elimina-tes the need of a yard manwhen driving backwards.

The inspection system

The SPERRY RAIL SERVICESYSTEM was chosen as theultrasonic isnpection system. Ithas the approval of the DB AGFTZ 9 and has been used in theSPERRY track inspection trainon tracks of the DB AG.The SPERRY ultrasonicinspection system RSU featu-res the measuring headsmounted rigidly inside a trans-parent soft rubber wheel andsurruonded by a fluid with gelconsistence. The connection tothe rail surface requires waterjust like the sliding measuringhead, but only a very thin film,because of the soft wheelmaterial. Thus the amount ofwater to be carried for the ridesis reduced substantially. Thisadvantage enhances the eco-nomical application of the HI-RAIL inspection vehicle.The measurements are donethrough nine channels with thefollowing arrangements: Onevertical test head and eightangular test heads. The angulartest heads include six 70° testheads, three each above therail head, pointing forward and

track inspection vehicle (SPF) is placed onto the track

backward, and two 37° testhedas in the center, also poin-ting forward and backward. Ithas to be stressed that some ofthe angular test heads irradiateunder an angle into the railhead so as to catch also flawsat the edge of the head.Additional extra test heads canbe added later in another RSU.The entire test system is hou-sed in a test rack with fourwheels, which can be loweredhydraulically from the back ofthe trunk onto the tracks beforethe inspection ride starts. Thetest rack remains connected tothe vehicle, but no longer rigid-ly as before; it is rather beingpressed vertically and horizon-tally against the tracks by ahydraulic system. This assuresthat the test wheels are keptcentred to the tracks. Thus areproducible „test path“ is war-ranted. The measuring systemsof this equipment correspond tothe systems of the track inspec-tion trains already in use.The inspection rides can bedone at a speed of up to 50km/h, depending on the condi-tion of the track and the rail sur-face. The possibility of drivingboth forward and backwardduring the inspection permits toreplace the manually inspec-tions in a more efficient way.The Eddy current measuring

system supplements the ultra-sonic measurement in theareas near the rail surface. Ithas four test heads spreadevenly from the guiding edgeover the supporting surface andserves mainly for detectingflaws from rail head checks. Inthe test rack there is space pro-vided for as many as four Eddycurrent heads for each rail. Thesystem is scheduled for theinstallation of Eddy currentdetectors by middle of this year.

The trunk design

The air conditioned trunk hou-ses the entire electronics andthe evaluation system. Theelectrical supply comes from agenerator or - if possible - froman external source. Inside thetrunk there are also watertanks, a small mechanicalworkplace and cabinets foradditional equipment andspace parts. There is also theinspector´s workplace. He sitstoward the back in front of themonitors and sees through alarge pane down to the testrack and the tracks.This view ofthe tracks is recorded synchro-nously by a video cameramounted to the vehicle. Theinspector has voice contactwith the driver cabin during thetest ride. Roads landmarks arenoticed from certain signalsources and recorded in thetest report from the driver´scabin. An automatic route mar-ker records the covered sec-tions to assure a geographicalposition of fault spots.In addition, essential faults of acertain size are marked with anautomatic colouring system at

track-parts catched by the RSU-testing-system

workplace of inspector

the concerned rail position.During and after an inspectionride the recorded data have tobe evaluated. The measuringresults can either be enteredinto a data carrier or transmit-ted to the client within a shorttime.

The operation logistic

The inspection schedule can bearranged according to therequirements of the client. Thevehicle can move on the tracksby itself following a superimpo-sed time schedule as a selfpro-pelled vehicle because of theclassification as heavy auxiliaryequipment.The inspection vehicle travelson public roads to the site of thescheduled engagement and isthere placed onto the trackwhereupon all applicable ope-ration instructions and writteninstructions have to be follo-wed. This process is easy ontrack level roads crossings butthe vehicle can also be placedonto the tracks on suitable

sidings or similar locations bymeans of ramps, with which it isequipped.It is ready to operate as heavyauxiliary vehicle as soon as thetrack guide wheels were lowe-red and the steering wheelshave been locked. Further tra-vel has to follow railway rulesand -time tables.At the endpoint of the schedu-led operation the track guidewheels have to be raised andthe steering system unlocked.The SPF can now leave thetracks at a road level crossingor over the ramps. Thereafterthe tracks must be reported„unoccupied“ according to rail-road rules.Being again a road vehicle,necessary maintenance servi-ce can be provided at a suitableloading area or parking space.

Authors:Dipl.-Ing. SFI-OS Klaus Meißner, formely with DB Netz Zentrale

Dipl.-Ing. SFI-OSRüdiger PetruschManaging Directorpethoplan gmbh

track inspection vehicle (SPF) with lowered inspection system