Rail Monitoring

A void is a gap that opens up between a sleeper and the ballast beneath it. When a train passes, the unsupported sleeper and rail are pushed down into the gap, then spring back up. Every passing train repeats that movement, so a small void soon grows. It wears the ballast, damages sleepers and fastenings, and throws track geometry out of line.

Left unchecked, voids lead to poor ride quality, higher maintenance costs and, in the worst cases, broken rails, emergency speed restrictions or line closures. Voids are hard to spot by eye, because the track can look sound when no train is on it. Manual void meter readings mean sending staff onto live track and capture only a snapshot. Continuous, remote monitoring shows how the track really behaves under traffic, day after day.

Benefits of remote track void monitoring

• Find voids early: small voids are picked up before they damage sleepers, fastenings and affect track geometry.
• Plan maintenance, don't react: tamping and other repairs can be booked into planned possessions instead of emergency call-outs.
• Fewer speed restrictions: fixing voids before they worsen avoids the restrictions that follow track faults.
• Safer working: remote readings replace repeated manual void meter checks on live track.
• Real-world data: measurements under actual train loads show how the track really behaves, not a one-off snapshot.
• Proof that repairs worked: monitoring before and after maintenance confirms whether a void has been fixed.

More than products – an end-to-end service

Buying sensors is only part of the answer. DYWIDAG supports you and your project partners, including designers and main contractors, from the first site assessment to long-term operation, with geotechnical and monitoring specialists at every stage.

• Advise: we review your slopes and earthworks, assess the risk and help you decide what to monitor, where, and with which technology. We help set trigger levels and response plans that match your operating rules.
• Design: we design a monitoring system for each site, choosing between automated, manual or combined monitoring depending on the risk, access and budget.
• Install: our own teams install and commission the system on site, including on steep or hard-to-reach slopes using in-house rope access teams. We work within track possessions, road closures and site safety rules.
• Operate and maintain: we look after the sensors, power and communications, so the system keeps working through every season.
• Interpret and respond: our engineers help you understand the data, review alerts and recommend next steps, from closer monitoring to long-term stabilisation using DYWIDAG systems.

One partner, from first conversation to final report, means fewer interfaces, clearer responsibility and faster decisions when it matters.

Most monitoring suppliers can tell you a slope is moving. DYWIDAG can also help you fix it. We supply proven slope stabilisation systems, including DYWI Drill hollow bar soil nails, Threadbars, and high-tensile mesh, with technical support. At Edenbridge Cutting in the UK, 226 DYWI Drill hollow bars and 150 m² of high-tensile mesh were installed within a nine-day rail closure, to stabilise a cutting with a history of landslips.

Monitoring before stabilisation shows where the risk is. Monitoring after shows the fix is working, so you can prove it to regulators, insurers and your own board

DYWIDAG rail survey services give rail operators, infrastructure managers and contractors accurate, independent information about the position and condition of their track and structures. That supports safe decisions on maintenance, renewals and works next to the line.

Our in-house survey teams carry out 3D track surveys against known benchmarks. These show how track, bridges, tunnels and earthworks are moving, and whether rectification is needed. For UK projects, surveyors hold Personal Track Safety (PTS) certification as a minimum and work to Network Rail standard NR/L2/CIV/177 or equivalent. Teams follow the matching local safety and survey standards on other networks. We work alongside track maintenance and rectification teams, and can issue tailored reports within minutes of the work on site. A survey can stand alone, set a baseline before nearby construction, or be the first step towards continuous automated monitoring on DYWIDAG’s Infrastructure Intelligence platform

Any work undertaken beside, beneath, or on the railway, has to be proven not to have disturbed the track. For piling or excavation next to a live line, embankment strengthening, bridge works or dewatering, the railway normally has to keep its full permissible speed, so track geometry must remain within tolerance at all times, and any deviation be known within minutes by the site team and the asset protection engineer.

For an under-track crossing, the question is whether the drive has settled or heaved the track, and whether the line can be handed back at full speed when the shift ends. DYWIDAG provides remote track geometry monitoring as a complete service for all of these, from baseline survey to handback record.

Automated total stations (ATS), GNSS and laser scanning add absolute movement and a digital baseline, so the handback survey is compared against the same record as the monitoring. In Infrastructure Intelligence, movement at an intervention limit alerts stakeholders within 15 minutes and movement beyond threshold alerts immediately, with live data and daily reports for all parties. Installation and removal are staged with the construction programme.

• Automated total stations, GNSS and 3D laser scanning for absolute movement and a digital baseline, so monitoring and handback survey share one record
• Cant and twist plotted continuously, read against the position of the works
• Alerts within 15 minutes of an intervention limit, and immediately beyond threshold
• Live data, trends and daily reports for the contractor, the designer and the asset protection engineer together
• Under-track crossings, adjacent piling and excavation, embankment strengthening and bridge works, through to handback
• Installation and removal staged with the construction programme, within short access periods

A railway tunnel can be inspected only in a possession, Between possessions any remote works, including piling, excavations, or nearby new tunnel drives, can influence the ground around the tunnel, resulting in changes in load distribution. Structures, including platforms, viaducts and retaining walls are also monitored

DYWIDAG instruments tunnnels, portals and structures, so that the cross-section, profile, and condition of cracks are known during normal operation. Monitoring is undertaken throughout any works that could affect the tunnel/structure and during strengthening or relining.

Convergence arrays, tilt sensors and crackmeters report through data loggers, gateways and repeaters along the tunnel, where mains power and communications are rarely available. Automated total stations track prisms on the lining, laser scanning and point cloud surveys measure the bore profile against the kinematic envelope, and camera-based inspection records the lining between visits. In Infrastructure Intelligence, readings are plotted by chainage with alarms against agreed thresholds, and where a tunnel passes beneath or beside works, lining movement is read against the ground and track geometry monitoring for the site.

• Convergence, shape arrays, crackmeters and tilt sensors on the lining and portals, reporting through loggers, gateways and repeaters along the bore
• 3D laser scanning, point cloud surveys and automated total stations, with clearance and gauging analysis against the kinematic envelope
• Lining movement read against the ground and track geometry monitoring for works above or beside the tunnel, with readings plotted by chainage
• Camera-based inspection of the lining between possessions
• Monitoring during strengthening and relining as well as in normal operation
• Coverage along the full bore without mains power or communications at the sensor
• SMS, Email, visual alarms against thresholds delivery by Infrastructure Intelligence