Interface - The Journal of Wheel/Rail Interaction

RAIL GRINDING

Specification and Documentation of Rail Grinding Work in Europe (continued)

For the transverse profile, the shape and production tolerance must be specified. The European norm requires the contractor to produce the target profile that is given by the railway. German railways generally request all rails to be ground to the 60E2 geometry, which is derived from the UIC60 rail profile. Another specified profile, called the gauge-widening profile, provides 2.5mm gauge widening on each rail. French railways start with the basic UIC60 profile, which is inclined 1/20. Other target profiles, such as anti-headcheck-profiles, which provide gauge corner relief, have since been developed. Depending on the amount of gauge undercutting, they are called preventive or corrective profiles. Banverket, the Swedish infrastructure company, has designed a specific "MB3" target profile for its ore line in the north. This profile, which is completely different from the installed rail profile, was designed to better accommodate hollow-worn wheels. Figure 4 shows a newly developed target profile created in Austria. This so-called convex rail assures stable running at higher speeds, while reducing rolling contact fatigue.

Tolerances are checked by superimposing the target profile over the measured in-track profile. Two reference points, one in the center of the railhead and one at the gauge reference point, are specified. A zone of maximum radial deviation from the target profile is specified for the gauge side of the rail. On the field side, the profile is checked to 5 degrees tangent.

The European specifications allow for three quality classes (see Figure 5). The most severe permits maximum deviation of +/- 0.3mm; the least stringent permits maximum deviation of +0.7/-1mm. (There is a percentage allowable outside these values.) Quality class Q, which is typically required for high-quality track, requires that 90% of all the recordings or the measured lengths must be within the range of +/-0.3mm; only 2% may be outside any specification. Quality class S requests only 75% to be within the 1.7mm range. German Railways (DB AG) and French Railways (SNCF) consider Quality class S standards to be too low, and require quality standards Q and R. In most cases, both rails must be measured at least once per grinding section, every 500 or 200 meters. On DB AG's high-speed lines, measurements must be taken every 50 meters.

Roughness is also specified. The rail grinding contractor must measure six points on each rail after grinding; only one may be outside the specified value of 10 microns. While the recording frequency is not specified, it is typically done once per grinding shift. Metal removal also is not specified. The typical metal removal rates are 0.3mm for new rail, and 0.2mm for cyclical preventive grinding programs. Metal removal rates for corrugation removal typically are 0.1mm below the corrugation troughs. Metal removal documentation, if required, must be provided at five locations at least 1/2 meter apart. Metal removal rates must be documented on a weekly or daily basis, depending on the railway.

Other criteria relating to "the finish" are included in the European specifications. Facet width, for example, should be less than 10mm on the crown radius, 7mm on the shoulder, and 4mm on the gauge side. The variation of the facet width should not be more than 25%. Additionally, the rail may not exhibit coloring or bluing after grinding.

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