On the new Alp Transit lines in Switzerland, Austria, Italy and France, ballastless tracks have become more and more important.

Advantage over ballast track include greater travel comfort since vibrations are reduced; a cut in maintenance costs; rail wear is reduced; and in tunnels, the lower vertical profile leads to reduced structural costs.
The tracks are held with tension clamps on a rib plate. Between track and rib plate, a rail pad is positioned. The rib plate itself is anchored by post-installed anchors into the concrete slab. Post-installing of the anchors is an appropriate solution because the concrete slab paver will not be constricted by block-outs or inserts.
The horizontal forces are transferred to the concrete slab over the rail anchors, which are subject to bending.
Under the rib plate, an elastomer pad is positioned to reduce noise and vibration. In order to prevent wear on the concrete surface, a thin HDPE pad is placed under the elastomer. The rib plate is force-fit tied to the concrete slab with spiral springs having stop nuts. As a result, the rail subsidence after each axle passage is absorbed elastically.
The track support should have the possibility of horizontal and vertical adjustments. Horizontally, it can be done continuously by eccentric collar bushes. Settlements of track slab can be compensated by shims.
According to the noise and vibration requirements, stiffer or softer elastomer pads are used. The softer ones with lower stiffness result in better noise isolation and in less vibration, but with the disadvantage that bending in the rail anchors will be increased.
The track and the rib plate are insulated from the concrete slab by the plastic collar bush. To avoid contact with rebars in the concrete, the anchors should be provided with plastic centre rings, which result in complete coating of the anchor with injection material.
Hilti offers five different rail anchors (different axle loads and velocities), which covers the aforesaid features with the required approvals.
The approval of EBA (Eisenbahnamt Deutschland) includes the complete track support loarg 336/Hilti as well as the Hilti rail anchors itself.

Enquiry No 19

Hilti Corporation, is based in Schaan, Liechtenstein. www.hilti.com