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

Potential Leicester to Coventry rail link mulled over in updated Leicestershire transport vision

22/02/2019Potential Leicester to Coventry rail link mulled over in updated Leicestershire transport vision

The potential of a Leicester to Coventry rail link has been revived again as one of the key highlights of a new transport masterplan outlined by ... more >
Queues of 15,000 and Eurostar chaos at St Pancras in no-deal Brexit

22/02/2019Queues of 15,000 and Eurostar chaos at St Pancras in no-deal Brexit

Eurostar queues of up to 15,000 passengers could mount up at London’s St Pancras International station in the event of a no-deal Brexit, ac... more >
New head of safety and environment for Hull Trains announced

21/02/2019New head of safety and environment for Hull Trains announced

A new head of safety and environment has been announced by Hull Trains, with Mark Shepherd due to replace Phil Green in the role. Bringing m... more >
RAIB launches investigation after passenger fatally struck at Tibberton footpath crossing

21/02/2019RAIB launches investigation after passenger fatally struck at Tibberton footpath crossing

The Rail Accidents Investigation Branch (RAIB) has launched an investigation into the death of a pedestrian who was fatally struck by a train whi... 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

TfN Strategic Transport Plan: not just for transport's sake

22/01/2019TfN Strategic Transport Plan: not just for transport's sake

Peter Molyneux, Transport for the North’s (TfN’s) strategic roads director, has been leading on the development of the seven economic... more >

the sleeper's daily blog

Williams Rail Review: The end of saying sorry?

05/02/2019Williams Rail Review: The end of saying sorry?

Keith Williams’ ongoing Rail Review presents a golden opportunity to rebuild the industry’s weakened relationship with its users and set it on a better track for the future, argues David Sidebottom, passenger director at Transport Focus. Passengers waiting at stations today are not peering down the line looking for a strategy ... more >
read more blog posts from 'the sleeper' >

comment

TrackWater: Embracing data in flood prevention

05/02/2019TrackWater: Embracing data in flood prevention

Mike Harding, from Lancaster University’s Data Science Institute, introduces us to TrackWater: an innovative project between Lancaster Univ... more >
High-speed rail cannot stand in isolation

05/02/2019High-speed rail cannot stand in isolation

Last year, the Scottish Government announced two feasibility studies to better understand the economic and environmental implications of options ... more >
Flying Banana reaps the fruit of its labour

05/02/2019Flying Banana reaps the fruit of its labour

Steve Quinby, Network Rail’s head of data collection, gives us the rundown on the state-of-the-art ‘Flying Banana’ train. ... more >
Introducing the new Passenger Assist app

05/02/2019Introducing the new Passenger Assist app

Jacqueline Starr, managing director of customer experience at the Rail Delivery Group, explains how a new app developed for the rail industry wil... more >

rail industry focus

View all News