Scientists map the exact weather conditions that trigger railway noise
Researchers tracking squealing trains in Sweden have identified precise environmental triggers—humidity, temperature, and time of day—that predict when wheels will screech on curves. The findings could help transit operators reduce one of urban rail's biggest noise complaints by adjusting maintenance schedules or track treatments based on seasonal weather patterns.
Originaltitel: Statistical analysis of railway curve squeal occurrence on the low and high rails in relation to environmental conditions
Tågkurvor genererar bullerande hjulskrik genom friktion mellan hjul och räls — ett miljöproblem som kan bekämpas genom att förstå när det uppstår. En ny statistisk analys från Luleå tekniska universitet och Trafikverket identifierar helt olika miljöberoenden för skrik på låg respektive högrail, vilket pekar på skilda fysikaliska mekanismer. Lågrailsskrik förekommer huvudsakligen vid relativ luftfuktighet 55–75 procent, absolut luftfuktighet 7–9 g/m³ och temperaturer 7–15 °C, med toppar på morgnar och hösten. Högrailsskrik dominerar vid torr luft och högre temperaturer. Båda minskar drastiskt vid låga temperaturer och höga fuktighetsnivåer. Resultatet möjliggör målinriktade bullerdämpningsstrategier för järnvägsoperatörer och infrastrukturkoncessionärer. För infrastrukturleverantörer och underhållsentreprenörer skapar kunskapen grund för väder- och årstidsberoende underhållsschemaläggning samt friktion- och dragkraftsstyrning på kritiska sträckor.
<p>Railway curve squeal is a significant source of environmental noise, arising from friction-induced instabilities in the wheel–rail contact. These instabilities are influenced by prevailing friction conditions which are affected by environmental factors such as humidity and temperature. This study presents a statistical analysis of long-term curve squeal measurements from a curve operated by commuter trains in Sweden. The analysis focuses on the relationship between environmental variables and squeal occurrence, distinguishing between squeal generated on the low and high rail. The results reveal distinct differences in squeal tendencies. Low rail squeal is most likely during relative rail humidity 55%–75%, absolute humidity 7–9 g/m3, and temperatures 7–15 °C, with peak occurrence in the morning hours and during the autumn season. The probability decreases notably outside these ranges. A specific range of estimated friction coefficients is also associated with low rail squeal. Conversely, high rail squeal exhibits increased probability during dry conditions and elevated temperatures. Both low rail and high rail squeal probabilities are reduced during low temperatures, rail temperatures close to the dew point, high relative humidity, and during the winter season. The observed differences suggest that separate mechanisms may be responsible for squeal on the low and high rail, involving wheel tread contact on the low rail, and wheel flange or two-point contact on the high rail. The results provide new insights into the environmental dependencies of low rail and high rail generated curve squeal, which can support the development of targeted squeal noise mitigation strategies. </p>