In late June, the South Rail Systems Alliance (SRSA) successfully tested cutting edge curved laser technology during a plain line renewal weekend possession at Stonehouse, Gloucestershire.

The renewal was on the UP Charfield passing over Stonehouse Viaduct. The renewal consisted of:

  • CAT11, renewal from 102m 107y to 102m 288y (181y)
    • EG47 shallow depth sleepers
    • 250mm bottom ballast
    • CEN60 rail
  • Guard Rails over viaduct
    • Guard Rail ‘Run on & Run off’ panel

The SRSA implemented tighter than standard installation tolerances during the core installation weekend, in the aim to achieve great track quality. On handing back the core renewal to Network Rail after the weekend possession achieved a planned high speed hand back (HSHB) of 90mph, following successful implementing of their Progressive Assurance Process.

Curved Laser Implementation

To further improve the quality of track renewal installation, the SRSA sought to implement the use of curved laser technology. With the delivery of our new fleet of Tampers came fitted with curved laser technology, with the plan to trial this technology during the Stonehouse renewals to implement on future sites.

To ensure the application of curved laser was a success, the SRSA worked collaboratively, this included collective training between tamper crews and site engineers to all understand their role and requirements.

In addition, the SRSA reached out to Tamper manufacturer, Plasser who arranged for a curved laser expert to attend the first curved laser tamping shift. The trial was a resounding success, with the result of outstanding track quality for a spate tamp handback to line speed of 100mph.

The site team were faced with the challenge of maintaining social distancing as part of the UK Government Guidelines for COVID-19. Even with these restrictions in place, the team successfully worked safely together, carrying out initial training through Microsoft Teams and managing the risk of social distancing during site operations.

The collaboration of improving quality of deliverables throughout the SRSA will continue, with the alliance striving to achieve the best track quality utilising quality installation methods, HSHB, implementation of curved laser and further track quality improvements being implemented over the coming year.

What is Curved Laser?

The curved laser is capable of implementing its technology on works through plain line sections of track and Switch and Crossing (S&C).

The curved laser consists of two components:

  • A laser receiver fitted to the Colas Rail UK tampers
  • A laser front trolley, which when set up allows detection and rectification of long wave track faults, which will contribute greatly to achieving great track quality.

Speaking about the quality of the work, SRSA Head of Transformation, Nick Matthews said:

“On a Tamper there are 3 measuring points “A, B & C”. Point A it at the front of the tamper, Point B is at the tamper banks and Point C is at the rear of the tamper. The distance between point A & C is called the chord. The perpendicular measurement between the Chord to point B is called the versine. The tamper calculates the differences between the actual versine and design versine (horizontally and vertically)  and moves and tamps the track to the adjusted position.

The longer the chord length between A&C the more accurate the versine calculation will be at point C. However the length of the tamper limits the chord length between A&C.

Curved laser increases this chord length by placing point A on a trolley that can be up to 200m ahead of the tamper. This greatly increases the chord length and so the accuracy of the tamp.

This increased accuracy of tamping will ensure much smoother track being constructed in both short and long wavelengths and so ensuring far greater passenger comfort and greater asset life.

Curved laser needs the track engineers and tamper operators to work as one. Using the strength of the Alliance this essential partnership is greatly enhanced and has allowed the SRSA to work together to deliver this exciting innovation”

The SRSA is an Alliance consisting of Colas Rail UK, Network Rail and AECOM.