RHEDA RX: effective protection from structure-borne noise
Rapid transit can mean rough conditions. The RHEDA RX ballastless track system masters with ease the great loads arising from metro transport and minimizes undesirable vibrations. The system was developed especially for use in metro lines with speeds up to 100 km/h and axle loads up to 18 tons. RHEDA RX was designed as a mass-spring system and consists of a concert supporting slab with integrated bi-block sleepers that rest over their entire surfaces on RockXolid® stone-wool mats. RHEDA RX, developed on the basis of the proven RHEDA ballastless track system, is characterized as trackform by an in-situ-concrete slab with integrated bi-block sleepers. Since initial RHEDA employment in 1972 at the German station Rheda, which gave the track form its name, RAIL.ONE has systematically further developed this solution and has adapted it to changing requirements.
RHEDA RX is a ballastless track that is designed as a mass-spring system supported elastically over its entire surface. This solution effectively isolates vibrations resulting from passing trains. The system forms a mechanical filter below the track superstructure, which is superior to damping within the superstructure. The reason for this greater effectiveness is the greater mass above the elastic layer.
Design of the system is always project-related. Implementation includes consideration of a great number of vibration-relevant parameters, and the use of multi-degree-of-freedom (MDOF) track model provides prediction of insertion loss for vibration isolation. Subsequently definition likewise takes place for the optimal combination of slab thickness and type of elastic mat.
Owing to the restricted conditions in railway tunnels, as well as the resulting difficulties for supplying and handling materials there, crucial requirements result with respect to logistics and installation methods. RHEDA RX satisfies these constraints by requiring reduced quantities and weights of materials, construction support, and machines necessary on the construction site – and by its carefully designed installation methods.
The type and amount of RockXolid® mats are determined early in the planning phase. The second step consists of preparation of an layout plan, and the mats are prepared project-tailored at the factory. Individual elements of the matting can be laid at the construction site by hand and without use of machines. The pre-customized sizing additionally reduces the cutting waste of the matting to a minimum. The mats are then covered with plastic sheeting to prevent intruding concrete and thus forming acoustic bridges. The mats can support walking and vehicle traffic, which means no restrictions for track construction. The mats are emplaced loose, thereby guaranteeing fast as well as smooth installation.
Provision of the RHEDA RX supporting slab takes place according to the top-down principle – whereby the rails serve as reference for installation of the track. In combination with the benefits of bi-block sleepers – with which track-geometric dimensions such as gauge superelevation are exactly defined in advance – the installation techniques lead to highly exact track geometry after installation.
With the exception of the freely accessible rails and rail-fastening systems, no maintenance measures are required for RHEDA RX. This also especially applies to the central component of the system: the stone-wool mats installed between the concrete supporting layer and the tunnel invert. The mats were designed with special consideration taken of these required characteristics. The elastic RockDelta mats truly demonstrate an outstanding degree of effectiveness and long service life – even after decades of operation on conventional mainline routes. The elastic mats also allow the use of stiff and therefore simpler fastening systems from all leading manufacturers. This significantly reduces loads placed on the fastenings and appreciably extends life cycles. All components are simply accessible at all times and can be easily disassembled and exchanged.