17  EP 3 800 002 A1 18  rail (36), preferably two rails, of a railway track (38), the method comprising: -providing,on the track (38),a train (40)accord- ing to claim 13; and - performing a beam delivery method that in- cludes: * transmitting at least one laser beam (8) through a respective atleastone beampas- sage (6) of a shield (4); * at least partly focusing the at least one laser beam (8) on the at least one beam passage (6); and * providing a fluid flow (F) through the  at least one beam passage (6), *wherein the beam deliverymethod prefer- ably further comprises performing laserab- lation using the at least one laser beam; wherein the at leastone laser beam (8) is preferably directed at the at least one rail (36), in particular at a running surface (34) of said rail (36), wherein pref- erably the methodfurthercomprises removing liquid, e.g. rain water, from the at least one rail (36), in par- ticular from the running surface (34) of said rail (36), by a flow of gas, e.g. air. -transmitting atleastone laserbeam(8)through a respective at least one beam passage (6) of a shield (4); - at least partly focusing the at least one laser beam (8) on the at least one beam passage (6); and - providing a fluid flow (F) through the at least one beam passage (6), wherein the method preferably further comprises performing laserablation usingthe atleastone laser beam. - providing a transport system (44) according to claim 14; and - preforming a method according to claim 15 for treating at least one rail (36) of a railway track (38) of the transport system (44). 16. Beam delivery method, comprising: 17. Method of operating a train service, wherein t he method comprises: 10