Inbox

24.07.15

Detecting track defects

Source: P.C Johnson

In the 1970/80’s various test trains were developed as individual facilities to assess various track features and brought into service as separate operations. Four of these major units were the Ultrasonic Test Unit, Track Recording Unit, the Structure Gauging Train and Lab 5, a track Recording Coach already in long term use. Even at that time there were thoughts of eventually combining these operations into a possible single unit to reduce line occupancy, costs and some of the duplicated staffing aspects. In a combined arrangement the speed of testing would be determined by the test requiring the lowest testing operational speed requirement and possible light level requirements.

The track recording facilities could work at any speed up to line speed with a constraint of a comparatively slow minimum low speed. The installation of track recording facilities as a unit on conventional ‘in traffic’ stock gives some aspects of the track being travelled over but does not give specific detailed information and tends to be influenced by the riding characteristics of the vehicle conditions on which it is installed. The Structure Gauging facility worked at similar but preferably slightly lower speeds principally at night. The Ultrasonic facility had the lowest speed requirement determined by the time taken for the transmitted shear wave ultrasonic energy to return from the bottom of the rail and the pulse spacing to ensure full coverage. This restricts the speed of operation to around 20 to 30mph.

My recollection of detected in track rail defects and failures indicated in general they were usually located in the upper half of the rail. Rail-end defects in the lower web were usually associated with other defects in the upper half of the rail. The few other true rail foot defects usually occurred in known galling and corrosion areas and could be accommodated accordingly.

Testing down to mid-rail depth would allow a significant increase in testing speed. However this approach would not be without difficulties, needing to ensure residual energy from consecutive events did not interfere. With an increase of speed it would be necessary to maintain the density of pulsing to ensure full examination coverage. However with the current computing facilities available and a designed multiple probe arrangement it should be possible to produce a system to overcome these problems.

Work to enhance the fracture toughness of rail steels would also improve defect resistance to failure. A more extensive use of the more expensive, but probably cost effective, rolled High Manganese steel rails, in vulnerable areas, with their tolerance of significant cracks without failure. Although this material does carry penalty of a lower propagation speed of ultrasonic energy adding to difficulties in automated processes.

Filming of track and pantograph features could also be incorporated with its own constraints. In consequence I would suggest it should be possible, with careful planning, to carry out several measurement features on the same train/unit simultaneously reducing costs and track occupancy.

Re: Current IM fleet data collection service 'unsustainable'

Comments

There are no comments. Why not be the first?

Add your comment

 

rail technology magazine tv

more videos >

latest rail news

Rail industry launches new interactive accessibly map for UK rail stations

17/04/2019Rail industry launches new interactive accessibly map for UK rail stations

A new interactive map which lets passengers find out about accessibility at stations has been launched by the Rail Delivery Group (RDG) to help b... more >
Helium balloons causing ‘increasing number of train delays’ at cost of £1m

17/04/2019Helium balloons causing ‘increasing number of train delays’ at cost of £1m

Helium-filled balloons are causing hundreds of train delays at a cost of £1m in taxpayer money every year, Network Rail has revealed. ... more >
Dawlish sea wall gets council planning approval with construction to begin in May

17/04/2019Dawlish sea wall gets council planning approval with construction to begin in May

Plans for an £80m sea wall to protect the Dawlish coastal rail line from extreme weather have been by approved by Teignbridge District Coun... more >
Stagecoach and MPs demand answers in dispute over ‘staggering’ pensions fund deficit and rail franchise controversy

16/04/2019Stagecoach and MPs demand answers in dispute over ‘staggering’ pensions fund deficit and rail franchise controversy

MPs have asked The Pensions Regulator (TPR) to reveal the extent of the “substantial” deficit in the Railways Pensions Scheme and pro... more >

editor's comment

23/01/2018Out with the old...

Despite a few disappointing policy announcements, especially for the electrification aficionados amongst us, 2017 was, like Darren Caplan writes on page 20, a year generally marked by positive news for the rail industry. We polished off the iconic Ordsall Chord (p32), hit some solid milestones on Thameslink (p40), progressed on ambitious rolling stock orders (p16), and finally started moving forward on HS2 (p14) ‒ paving the way for a New Ye... read more >

last word

Encouraging youngsters to be safe on the railway

Encouraging youngsters to be safe on the railway

This summer, Arriva Group's CrossCountry and the Scout Association joined to launch a new partnership to promote rail safety among young people. Chris Leech MBE, business community manager at the TOC, gives RTM an update on the innovative scheme... more > more last word articles >

interviews

Women in rail - is the industry on the right track?

12/03/2019Women in rail - is the industry on the right track?

RTM sits down with Samantha Smith, sole female member of the TransPennine Route Upgrade Alliance Leadership Team, to find out more about encourag... more >

the sleeper's daily blog

West Midlands Rail Executive’s Malcolm Holmes on the 30 year Rail Investment Strategy and working with Midlands Connect

08/04/2019West Midlands Rail Executive’s Malcolm Holmes on the 30 year Rail Investment Strategy and working with Midlands Connect

Malcolm Holmes, Chief Executive of the West Midlands Rail Executive, joins us to discuss the 30-year Rail Investment Strategy, and how he and his team are working closely with Midlands Connect to deliver on uplifting capacity and bettering services for people across the region ahead of TCR Midlands 2019. What do your roles as Ex... more >
read more blog posts from 'the sleeper' >

comment

Changing the London skyline with HS2

26/03/2019Changing the London skyline with HS2

Lisa Hogben, HS2 programme delivery manager for area south enabling works, explains how the arrival of HS2’s first tower cranes shows chang... more >
Picking up the pace with high-speed track handovers

26/03/2019Picking up the pace with high-speed track handovers

In 2018 Steve Featherstone, programme director of track at Network Rail, set his team a challenge to secure 100 high-speed track handovers in a y... more >
26-30 Railcard: taking advantage of opportunities

19/03/201926-30 Railcard: taking advantage of opportunities

After a nine-month national trial, the rail industry launched its seventh National Railcard for 26-30-year-olds on 2 January 2019. Rail Delivery ... more >
Caledonian Sleeper: a railway icon re-imagined

19/03/2019Caledonian Sleeper: a railway icon re-imagined

The world-renowned Caledonian Sleeper, due to begin operations at the end of spring 2019, completed its first Scotland to London journey earlier ... more >

rail industry focus

View all News