Innovation of Crossing – System Ultra High Performance Crossing

2021-08-18 |

From the standpoint of a wheel, the crossing area of a turnout can be characterized as an uneven transition area. With rigid frogs, the components in this confined region are subject to high stresses when the wheel transfers through the gap in the “throat” of the frog from wing rail to block tip and vice versa. The newly developed Ultra High Performance Crossing (UHPC) from voestalpine Turnout Technology Germany GmbH provides a remedy for this issue.

Ultra High Performance Crossing

The UHPC uses forged wing blocks in the transfer region made of the low-wear material chrome bainite (CrB 1400) to bolster this highly stressed area.

Instead of rolled rail profiles, forged wing blocks and a forged block tip are used to exploit the outstanding performance of the chrome bainite. The manufacturing technology - mainly machining - allows the production of a precise contour, thereby avoiding internal stresses caused by the required heat input and subsequent bending and buckling. This technique also makes surface optimization possible on the wing blocks.

Advantageous properties of the crossing type UHPC

Force and form locking

With the UHPC , the fittings are supported or relieved by the insertion of form locking elements. These form locking elements absorb longitudinal forces from the track. While the bolt is arranged inside the form locking element, it is unlocked. This arrangement ensures that bending and/or shearing stresses cannot affect the bolt under any circumstances.

Design of the wing block

Another advantage of the UHPC wing block is that the design is not limited to the rail profile. This significantly increases its potential scope of application. In this way, resistance jumps and associated stress peaks can be avoided.

Evaluation of a possible wing rail elevation

Several studies were carried out on the UHPC crossing, regarding a possible wing rail elevation and its effect on the transition behavior of the wheel.

The following test scenarios were evaluated:

Wheel transition behavior on a crossing with standard geometry
Wheel transition behavior on a crossing with wing rail elevation and adapted crossing profiling
Wheel transition behavior on a crossing with adapted surface inclination and crossing profiling

You can read the detailed explanations of the study, the findings and more about the operational test on the test track of DB Netz AG in the article on the right side.

Outlook

By using forged block material, previous rigid frog design restrictions can be lifted. Larger cross-sections provide a variety of design options to improve the construction of rigid frogs.

It should also be noted that the material grades are not limited to the use of chrome bainite for the tip and wing blocks. Usable materials also include the grades 350 HT and 400 HT.

Research at voestalpine Turnout Technology Germany is ongoing. One area of study, for example, is optimized transition region geometries, with consideration of milling-manufactured elevations.