# Field Investigation and Rapid Deterioration Analysis of Heavy Haul Corrugation
## 1 Introduction  
The Shenshuo heavy haul line, the transportation volume of which exceeds 260 million tons per year, is one of the most important freight lines in western China. It starts in Daliuta and ends in the west of Shuozhou. With increases in rail traffic volume and the axle loads, serious rail corrugation defects have appeared in some sections of the Shenshuo railway. Corrugation has resulted in an aggravation and worsening of defects in the track's structure, such as the fracture of fastenings, RCF defects, spalling, ballast crushing, etc. This has led to a sharp increase in maintenance costs and has affected the safety of heavy haul operations. Rail corrugation, as an intractable defect in the railway industry, has a history of more than one hundred years [1]. It mainly occurs in heavy haul railways, high-speed railways (HSR), and urban rail transit, which includes all types of railway lines. For HSRs, the main wavelength of the corrugation in China is 120-150 mm [2]. It occurs both in the curves and along the straight lines of track sections, while wavelength is around 40-50 mm in metro lines [3]. Due to variations in the track and transport conditions [4], the wavelength of the corrugation is often longer than 150 mm in heavy haul lines. Furthermore, many researchers have introduced corrugation as a basic excitation in their numerical models to analyze W/R dynamic interactions [5], selection of track structures [6], or mitigation of rail defects [7]. Hence, it is important to diagnose the characteristics of corrugation and its evolution process. [PERSON] and [PERSON] [8] summarized and classified the six typical rail corrugation modes according to the fixed wavelength mechanism and material damage mechanism. In 2012, they modified the understanding of the \"wavelength fix\" theory andintroduced some devices that support continuous testing in the corrugation inspection field [9]. Within corrugation research, reproducing corrugation and revealing the mechanism of its formation are important topics. As for research into damage mechanisms and the formation of corrugation defects, [PERSON] et al. [10; 11] studied the influence of vehicle speed and its non-uniform distribution on wear-type corrugation growth rates. [PERSON] and [PERSON] [4; 12; 13] analyzed the formation and development of corrugation at rail curves using [PERSON]'s rolling contact theory with non-Hertzian contact and friction work calculation for the worn-out material. Other than analytical methods, field inspections play an important role in corrugation studies. [PERSON] et al. [14] conducted a full-scale stand test to analyze corrugation formation mechanisms and concluded that the large creepage and vertical fluctuation of W/R force is the main reason for the formation of corrugation. [PERSON] [15] conducted a field experiment at a sharp curve line and analyzed the plastic material flow in the surface layer caused by the lateral creep forces. [PERSON] et al. [16] constructed a measurement system with 2D laser sensors and a data splicing method to enlarge the effective wavelength of the measured corrugation data. The topic of rail corrugation has attracted enough interest among researchers, and their research outcomes have been implemented in the mitigation of rail corrugation using a friction modifier [17; 18], a frequency regulation measurement [19; 20], and suggestions regarding the deficiency of current evaluation criteria have even been made [21]. Due to the complexity of the mechanism of rail corrugation, current understandings regarding corrugation are not sufficient to reach a consensus, and it still acts as a major and common defect in rail systems. Considering cost and installation difficulties, these mitigation measures are not always suitable for corrugation sites. Until now, the most effective and practical way to alleviate corrugation in a site was rail grinding.