Expansion joints

Expansion joints in the concourses and ticketing halls of mainline and mass transit rail stations not only have to cope with high levels of pedestrian traffic but in some instances also must be robust enough to resist the transport of mail and other goods which often means that heavily laden trolleys and pallet trucks travel across concourses and platforms.

Therefore, using the provisions of Eurocode EN-1991-1-1 ‘Actions on structures – General actions, densities, self-weight and imposed loads for buildings’ FL2 loading is recommended; FL2 equates to a forklift truck of 46kN (4.6 tonnes) fully laden weight.

Control joints

Control joints in internal floors in rail station concourses should be laid to form 6 metre x 6 metre bays to accommodate local moisture movement and to compensate for small deflections arising from thermal expansion and contraction. Control joints in such high traffic environments should have metal side plates to support the vulnerable edges of finishes.

Expansion joints

Expansion joints in below-ground concourses and ticketing halls of mainline and mass transit rail stations share many of the loading, impact and abrasion issues that their above ground equivalents experience. The traffic loading is similar and the provisions of Eurocode EN-1991-1-1 ‘Actions on structures – General actions, densities, self-weight and imposed loads for buildings’ should be used for reference. It is suggested that FL2 loading is applied FL2 equates to a forklift truck of 46kN (4.6 tonnes) fully laden weight.

The major difference arises where joints comprising metal frames and elastomeric seals are considered. We would advise that these should be avoided, and all metal systems used instead; however, where they are specified the elastomeric seal should be manufactured from VAMAC which offers high burn temperature and low toxic smoke emissions in the event of fire.

Control joints

Control joints in below-ground concourses should be laid to form 6 metre x 6 metre bays to accommodate small deflections arising from drying shrinkage and thermal expansion and contraction. In high traffic environments these joints should have metal side plates to support the vulnerable edges of finishes and use VAMAC low toxic smoke seals to accommodate movement.

Expansion joints

Expansion joints in above ground platforms share the same general specification as concourse areas and ticketing halls, however these platforms often extend beyond station overhangs and waterproofing of these joints becomes increasingly important. Pooling of water is likely and expansion joint waterproofing membranes should ideally cross-link to structural waterproofing and run across the platform and extend least 150mm up an upstands to form a fully watertight seal. Provision should be made for drainage in instances where waterproofing membranes are used beneath expansion jointing systems.

Control Joints

As many rail station platforms extend beyond the building envelope and are exposed to the elements, significant movement due to day/night and summer/winter thermal cycling may be experienced. As a result control joints should be laid at 3 metre intervals to form 3 metre x 3 metre bays to compensate for these deflections.

Control joints in high traffic environments should have metal side plates to support the vulnerable edges of finishes.

Expansion joints

Expansion joints in below-ground platforms should mirror those selected for internal, below ground concourses in terms of loading capacity, fire resistance and low toxic smoke generation of seals.

They differ however where Passenger Safety Doors are employed. Expansion joints running through floor finishes close to PSDs must be electrically isolated from the platform substrate. Normally this means using an electrical isolation membrane on top of the slab and up walls for 1.8m to 2.0m from the face of the PSD.

The volume resistivity of isolation products used these zones should exceed a minimum of 5 x 10¹² ohms-cm.

Metal-edged expansion joints (and any other metal objects that interrupt the floor and wall surfaces) should therefore coated in the approved isolation material prior to installation

Control joints

Control joints in below-ground concourses should be laid to form 6 metre x 6 metre bays to accommodate small deflections arising from drying shrinkage and thermal expansion and contraction. In high traffic environments these joints should have metal side plates to support the vulnerable edges of finishes and use VAMAC low toxic smoke seals to accommodate movement.

Where Passenger Safety Doors (PSDs) are employed control joints in floors need to be electrically isolated from the platform substrate. Normally this means using an electrical isolation membrane on top of the slab and up walls for 1.8m to 2.0m from the face of the PSD.

The volume resistivity of isolation products used these zones should exceed a minimum of 5 x 10¹² ohms-cm.

Metal-edged control joints (and any other metal objects that interrupt the floor and wall surfaces) should therefore coated in the approved isolation material prior to installation

Expansion joints

Precast segmental sections are generally used to construct elevated rail lines. Expansion gaps are left between spans to accommodate thermal expansion and contraction as well as live load deflections and vibrations arising from the passage of trains.

 These expansion gaps should be sealed ideally using preformed sealing tapes which expand and contract in response to structural deflection.