joint research and testing of innovative grinding applications - speno ...

Wolfgang Schoech 

Speno International SA 

Joint research and testing of innovative grinding applications 

JOINT RESEARCH AND TESTING OF INNOVATIVE GRINDING 

APPLICATIONS 

Dr Wolfgang Schoech 

Speno International SA, 26, Parc Château-Banquet, CH -1211 Geneva 21, Switzerland 

Tel: +41 22 906 4600, Fax: +41 22 9064601, e-mail: WS@speno.ch 

SUMMARY 

Speno International is essentially a contracting company engaged mainly in rail grinding. Research 

work is undertaken only occasionally, for instance in order to find new applications for grinding or for 

optimisation of existing ones. As co-operation between customer and contractor takes place virtually 

everyday in grinding practise on site, such research work may be beneficial for both parties. Investing 

common knowledge, expertise and experience results not only in extending the know-how. It also 

allows developing and applying innovative products and procedures that help to further improve wellestablished 

maintenance practices. 

Similarly, in committees drafting standards, as for instance within CEN (European Committee for 

Standardization), in international working groups established to undertake research work (e.g. 

“Innotrack”, a research project launched by the European Commission) and in several bilateral work 

programs representatives from the railway industry and contractors work together successfully. 

This paper outlines the necessity to cooperate closely in order to constantly upgrade performances in 

track and presents a selected number of specific cases showing the way to innovative products and 

processes as well as the results achieved by such joint research work. All this work would not have 

been possible without close cooperation between the railway organisations and the industry and open 

discussion between the involved partners. 

1. INTRODUCTION 

Rail grinding has become a routine 

maintenance operation for all types of railway 

traffic, might it concern conventional systems, 

dedicated high-speed lines or heavy haul 

operations. Looking back in history, many of 

the sub-systems modern grinding trains feature 

have been invented or further developed on 

the initiative of the contractor in order to 

increase the output of the machines with 

respect to productivity and quality, others on 

the demand of customers looking for solutions 

addressing specific problems. 

Examples to be named are the introduction of 

pivotable grinding units, independent pressure 

control of grinding motors or the development 

of sophisticated grinding units able to work in 

check rail areas and finally even through 

switches. 

Another field of applied research has been the 

development of new applications for rail 

grinding, such as special profiling of the rail 

head or efficient control of rolling contact 

fatigue. The joint development of appropriate 

specifications and strategies to optimise the 

effect of rail maintenance has to be mentioned. 

Newly developed hardware components 

resulting from research work can be tested 

fairly easily on site during routine operation 

without compromising production issues 

greatly. 

Testing new ideas regarding grinding 

applications is a much more challenging topic. 

There are no specific tracks available for 

experiments. The only way to move forward is 

testing under real conditions in track. Thus a 

very close cooperation between railway and 

contractor is required to assure efficient testing 

without interfering much with operational 

requirements. It is a challenging task using a 

commercially operated railway track under 

service conditions as test facility. However 

practice has shown how important and 

successful such work can be. 

2. GRINDING APPLICATIONS 

Figure 1 lists the applications of rail grinding as 

used today. Whereas profile correction and 

damage removal has been a routine operation 

AusRAIL PLUS 2011 

22 – 24 November 2011, Brisbane



New Rail Maintenance Trends In Europe 

Anti-Headcheck-Profiles and Preventive Cyclical Grinding 

since the introduction of rail grinding, the use 

of this technology to improve running 

conditions, to reduce lateral wear and to 

control rolling contact fatigue effectively is the 

result of fundamental research work. 

between the wheel and the rail. This was 

particularly useful as the test set-up allowed 

monitoring the effects on vehicles operating 

under real traffic conditions. 

Particularly the introduction of innovative 

special target profiles for grinding work would 

not have been possible without joint research. 

Figure 2: Extreme asymmetric profiles tested 

Figure 1: Applications for rail grinding 

3. TARGET PROFILE DEVELOPMENT 

Already in the nineteen-eighties testing specific 

transverse profiles to better control steering 

and to reduce lateral wear led to the practice of 

asymmetric rail profiling. More recently a whole 

range of new target profiles for grinding has 

been developed to improve high-speed 

running and to reduce the development of 

gauge corner fatigue. Some examples of 

specific research projects undertaken in 

Europe are discussed in the following section. 

Different types of vehicles, in particular 

locomotives, have been evaluated on a 

statistical basis. Important effects, such as the 

influence of train speed and weather 

conditions, just to name the most significant 

ones, provided interesting insight in the 

complexity of the wheel-rail interface. The 

huge amount of data collected made 

interpretation and evaluation of many specific 

parameters a challenging work. 

Long-term observations of the wear 

development by circumstantial profile 

measurements verified the expected reduction 

of the lateral wear. Today such profiles have 

become a standard option if lateral wear needs 

to be treated. 

3.1 Wear Reducing Profiles 

The possibility to improve steering in sharp 

curves has been studied in a long term project 

starting in 1985 by the Austrian Federal 

Railways (ÖBB) and Speno International under 

supervision of the University of Innsbruck/ 

Austria. [1] 

In order to explore the possibility to influence 

vehicle and bogie steering by changing the rail 

head geometry extreme profiles as showing in 

figure 2 have been produced in track. In that 

era it was a painstaking affair, as a grinding 

machine with fixed grinding stone inclinations 

had to be used. 

Extensive strain gauge measurements in two 

test curves (one with standard profiles, the 

other with specifically designed asymmetric 

profiles) provided data on the immediate effect 

of asymmetric profiles on contact conditions 

Figure 3: Test site with strain gauge recording 

3.2 Gauge Widening Profiles 

A less academic, pragmatic approach has 

been taken to attack the problem of tight 

gauge caused - amongst other reasons - by 

shrunken concrete sleepers. This problem 

provoked in Denmark and in Belgium unstable 

running conditions for particular rolling stock. In 

Germany it required actions in order to bring 

the gauge width back within the legal limits. 







The question was, whether grinding could help 

to widen the gauge without changing the basic 

contact conditions between wheel and rail. The 

approach taken and the solution found was as 

simple as effective: Developing appropriate 

grinding pattern allowed the nominal target 

profile for grinding (at that time the UIC60 

profile, now called 60E1) to be shifted relative 

to the rail head towards the field side, the 

smooth transition being provided by a wide 70 

degree facet at the lower end of the 13 mm 

gauge corner radius. 

When starting the first applications of gauge 

widening by grinding already more advanced 

machines featuring pivotable grinding units 

were available that helped to set-up respective 

grinding pattern and to achieve remarkably 

high production rates. Thus gauge widening by 

grinding is a very economic undertaking 

compared to changing fastenings and/or 

sleepers. 

Any amount of gauge widening could thus be 

produced. German Railways (DB AG) have 

specified a target profile, which - if applied on 

both rails - opens the gauge by 5 mm. Its 

contact area is identical with the standard 

profile. The transition is assured by a wide 70- 

degree facet at the gauge. [2] 

related metal removal rates has been checked 

in parallel with profile modifications. [3] 

Initially five different target profiles for grinding, 

within the - at that time - wide production 

tolerance band, have been ground precisely on 

various test sections. Twenty grinding zones, 

each 100 meter long and containing two 

recordings points in their centre have been 

selected from the beginning, including 

standard steel and heat treated grades. All 

these sections have been worked on in 

different intervals from one to three years and 

have been inspected and monitored three 

times per year. 

Figure 5: Grinding and recording at the test 

site near Würzburg/Germany 

Figure 6: Example of profile development 

Figure 4: Gauge widening profile DB AG 

3.3 Anti - Head check Profiles 

Probably the most circumstantial joint research 

work ever undertaken in track took place in 

Germany, where the appearance of rolling 

contact fatigue at the gauge, usually referred 

to as head checks on conventional lines 

became an increasing problem. At first the 

effect of rail profiling on the development of 

head checks has been studied. 

The originally intended test period of some 

three to four years has been extended and 

lasted finally 10 years, as after the first project 

phase the influence of grinding cycles and 

Figure 7: Example of head checking 

In total 1200 transverse profile measurements 

and the same number of magnetic particle test 

samples have been taken and evaluated. Over 

5000 photographs document the development 

of wear and fatigue. This detailed monitoring of 

transverse profiles and observation of the 







related head check situation confirmed the 

positive effect of - however carefully limited - 

gauge corner undercutting strikingly. So-called 

“Anti-head check-profiles” are a standard 

recommendation for cyclic rail maintenance 

work today. 

As described below in chapter 4, this research 

project contributed equally to understand the 

influence of selected steel grades and grinding 

cycles on rolling contact fatigue development 

and its control. 

3.4 Wear Adapted Profiles 

A similar project is on its way in Sweden, 

where the infrastructure manager Trafikverket 

together with Speno International follows the 

result of specific profile grinding at the only 

European heavy haul line, called 

“Malmbanan”. 

Due to the typical traffic conditions wheels 

wear to a more hollow shape and provoke 

therefore rolling contact fatigue on the 

standard target profiles for grinding. As a 

consequence specifically adapted new profiles 

have been developed, tested and have 

become a standard for rail grinding. [4] 

Figure 8: Target profiles at Malmbanan 

The results of that joint project are satisfactory. 

But situations may change. Not only has the 

axle load increased in the past. As a 

consequence the new vehicles have been 

fitted with new wheel profiles and maintenance 

cycles have changed with their introduction. 

Thus, it has been decided to continue the 

cooperation regarding the grinding strategy 

project for some time with a view to identify 

requirements or potentials for further profile 

optimisation. 

As a consequence at 6 locations in totally 43 

track sections the rails are regularly inspected. 

Numerous transverse profile recordings - at 

each catenary pole in the sections - are made 

in order to follow wear caused by grinding and 

by traffic. 

Additionally Eddy-Current-measurements are 

made before and after grinding in order to 

record the situation of the head checks. This 

will not only allow modifying the target profiles 

if necessary but also enable the infrastructure 

manager to optimise metal removal 

requirements and grinding cycles, as described 

later in chapter 6. 

4. GRINDING STRATEGY 

DEVELOPMENT 

In this context it is important to mention, that 

the above presented research programs 

address two topics: The first is defining optimal 

target profiles for grinding, which assure lowest 

contact stresses at the wheel-rail interface; the 

second is establishing an appropriate grinding 

strategy, which controls rolling contact fatigue 

effectively by simultaneously keeping artificial 

wear by grinding at a low level. 

The main task thereby is to select metal 

removal rates and to balance them against 

head check development and natural wear per 

grinding intervention and corresponding 

grinding intervals. Producing a specific target 

profile even within tight tolerances has become 

a routine operation today. However, metal 

removal can only be checked manually at 

selected points. Continuous monitoring of 

metal removal in absolute terms on a grinding 

machine is still on the wish list of the industry. 

Usually the average machine capacity per 

grinding pass and speed is known and is taken 

as constant, as is the expected growth rate of 

head checks, the rolling contact fatigue 

phenomenon with the largest occurrence at 

present. 

Therefore several research projects have been 

undertaken so far to study metal removal rates 

and to specify the number of required grinding 

passes and working speed as steering grinding 

parameters. The metal removal requirement is 

expressed usually in tenth of millimetres to be 

taken off in the centre of the rail head and in 

intervention cycles (usually expressed in 

million gross tonnes). 

4.1. Head check treatment – 

DB AG/Germany 

As outlined above, in Germany already in the 

nineteen-nineties surface fatigue, in earlier 







times only a well known phenomenon for 

heavy haul railways, has become a severe 

problem for conventional railways using 

locomotives deploying high traction forces, 

increased axle loads and augmented line 

speeds. Therefore German railways (DB AG) 

and Speno International have undertaken 

circumstantial research work in order to 

understand better that phenomenon. 

After having studied the influence of profiling 

on gauge corner fatigue resulting in production 

tolerances featuring gauge corner relief 

varying grinding cycles have been tested. The 

twenty selected test sections for the profile 

study have been ground to different degrees of 

gauge corner relief, hence different metal 

removal requirements, of course all within the 

specified tolerances of the target profile for 

grinding. 

The development of the profiles and surface 

fatigue has been monitored in the same way 

as before. It allowed determining the optimal 

profile shape and metal removal requirement 

depending fatigue growth. Unfortunately (but 

expectedly) the relation between crack growth 

and grinding interval varied according local 

parameters. Not surprisingly it has been 

decided that shorter cycles within lower metal 

removal requirements are in any case 

advantageous. The findings of this research 

work have later been implemented in a 

European wide research project, which 

described in chapter 6. 

4.2 Rail Maintenance Strategy – 

Trafikverket/Sweden 

The Swedish infrastructure manager 

“Banverket” now integrated in “Trafikverket” 

has followed the same approach of continuous 

cooperation as undertaken in Germany, and 

has decided to continue its applied research 

project on target profiles for grinding with a 

view to strategically prevent rolling contact 

fatigue. [5] 

Thus, the earlier selected maintenance 

strategy by grinding specific profiles and by 

removing a specified amount of metal from the 

rail surface cyclically is closely followed and 

may be adapted at any moment in order to 

optimise the chosen rail maintenance strategy. 

It has been found that natural wear by traffic is 

very low and the transverse profile does not 

change much between grinding interventions. 

More important is now the issue of the metal 

removal requirements. In former times just a 

minimum requirement was a specified. Today 

complete crack removal is the primary goal, 

keeping new or correctively ground rails more 

or less head check free or at least at an 

acceptable low damage level. 

More precise metal removal specifications are 

now in discussion. Probably an average value 

will be specified for the rail centre and some 

slightly higher value for the field and gauge 

corner, of course maintaining the specifications 

for evenness of the longitudinal profile and 

shape for the transverse profile (target and 

tolerance). 

The tricky part of the exercise is to find a way 

to translate the technical idea into a precise 

specification, which can be checked by 

everyone. That of course addresses again the 

question of how to continuously and precisely 

measure the work produced by the grinding 

machines. 

5. HARD WARE DEVELOPMENT - 

RFC - Recording System 

Typical examples for joint hardware 

development were the introduction of pivotable 

grinding motors in the early days of rail 

grinding or later on the incorporation of 

continuously measuring recording systems for 

the longitudinal and transverse profile of the 

rail head. 

In the last decade new recording systems to 

detect fatigue cracks have been developed. 

Such a system based on Eddy-Current 

technology is used by DB AG on a flaw 

detection vehicle in order to detect and to 

classify fatigued gauge corner areas. 

It was a logic step to consider the use of such 

a system on rail grinding machines, which 

would allow monitoring the reduction - 

respectively the elimination - of head checks 

during grinding work. A project team consisting 

of the manufacturer, the rail grinding company 

and the railway has been set up in order to 

combine existing knowledge and experience. 

First a respective prototype device has been 

built, incorporated in a grinding machine and 

then tested in track. The results obtained on 

the grinding sites by the prototype system 

have been compared with results coming from 

manual devices. Much had to be learned about 

rail surface conditions and crack geometry with 

respect to its influence on the recording 







system. The system measures the variation of 

an electric field caused by the cracks. Thus, 

damage depth, which is the top layer of the rail 

head surface that needs to be removed, 

depends on crack inclination and orientation. 

[6] 

Quite a number of modifications on the 

recording trolley were required to assure 

correct, high precision guiding of the probes 

closely over the surface, independent of the 

shape and wear situation of the rail. Equally 

laborious was the development of an 

appropriate software package allowing for 

online interpretation of the data. 

Respective activities are under way in 

Australia. 

6. DEVELOPMENT OF GRINDING 

STANDARDS – 

The “INNOTRACK” project 

In Europe an international research project 

funded by the European Commission on 

innovative maintenance practices for railway 

infrastructure (“Innotrack”) has been 

terminated recently. Its results are at present 

disseminated to help infrastructure managers 

in their task of economical maintenance of 

heavy duty tracks. 

This project also can be seen as a joint 

research work between infrastructure 

managers and contractors. First of all regular 

meetings of the working groups assured an 

intense exchange of knowledge and 

experience. Some specific test projects have 

been undertaken in laboratories by universities 

and research institutions. Other work packages 

concentrated on applied research. 

Figure 9: Eddy-current-system on a rail grinder 

Figure 10: Example head check recording 

Based on the experiences made a series of 

systems is now in use with selected grinding 

machines. Their continuous use under routine 

operational conditions has helped to further 

develop and fine-tune the system as well as to 

explore the limits. Of course, that development 

will never have a definite end. 

So far quite satisfactory results have been 

made. Due to the European railway conditions, 

i.e. mixed traffic on conventional lines using 

standard steel grades (R260) it will be 

interesting to see the performance of this socalled 

“HC-Grinding-Scanner” under different 

conditions, such as heavy haul operations. 

Results of such individual tests have been 

published and discussed earlier on. Due to the 

big number of project partners (well over thirty) 

and their previous works and experiences, the 

project setup allowed to complement, confirm 

and finetune the various conclusions. As the 

project moved on, a big number of 

deliverables, i.e. technical documents has 

been published. 

Within subproject SP5 the working group WP 

4.5 - originally named “Validation of new 

maintenance processes”, later referred to as 

“Rail Maintenance”, looked into the rail sector. 

Besides rail lubrication and friction 

modification, rail reprofiling - taking into 

account optimal steel grade selection - was the 

main topic addressed. 

This working group was ordered to produce 

four documents: 

“Review of Present Maintenance Situation” 

“Target Profiles for Grinding” 

“Grinding strategies” 

“Lubrication and Friction Management” 

Finally a summary document entitled 

“Guidelines for management of rail grinding”, 

containing the most important results has been 

produced and published. [7] 







There some of the experiences made during 

earlier projects described above have been 

incorporated and are now accessible for all 

interested parties. Furthermore UIC regarded 

this document that useful, that it has been 

transcribed in a so-called “TechRec”, a 

Technical Recommendation that – after review 

by experts – will be published by UIC and 

UNIFE. 

But even there the story does not even stop. At 

present a European Standard (prEN13231-5) 

is in elaboration describing the basics for rail 

maintenance. It is at present in its early 

drafting stage; due to the valuable results 

obtained in INNOTRACK it is considered to 

incorporate the above mentioned guidelines for 

management of rail grinding as an informative 

annex. 

7. CONCLUDING REMARKS 

All the above presented examples of joint 

research and testing of innovative grinding 

applications and related fields demonstrate 

quite clearly that combined efforts provide 

multiplied benefits. It is the daily routine 

contractual work, which triggers considerations 

regarding research. It is equally the desire for 

innovation which motivates the industry to 

reconsider the performance of its technologies 

and used machines. 

Only a pragmatic approach by motivated 

partners made it possible to achieve 

remarkable results. Who would dare to 

propose a ten years project? Who would invest 

in recording programs without being able to 

quantify the economic benefit? In today’s profit 

oriented world basic research and 

experimenting with innovative ideas just for 

curiosity is not rated high priority. 

However, following daily work with interest and 

exploring new ways of doing has proven 

successful. Apparently it is the engineering 

approach and the method of learning by doing 

- of course in a safe and well organised way - 

which helped to move forwards and which will 

hopefully continue to do so. 

8. REFERENCES 

[1] Schoech W, Kopp E: Asymmetric Railhead 

Profiling, International Railway Journal, August 

1989 

[2] DB AG: Richtlinie 824_4005A02, 2003 

[3] Schoech W, HeyderR, Grohmann HD: 

Contact Geometry and Surface Fatigue – 

Guidelines for Appropriate Rail Maintenance, 

Proceedings: 7th International conference on 

Contact mechanics and Wear of rail/wheel 

Systems, Brisbane/Australia, 2006 

[4] Schoech W, Frick A: Development of the 

Grinding Practice at Malmbanan, Proceedings: 

IHHA Conference Specialist Technical 

Session, Kiruna/Sweden, 2007 

[5] Schoech W, Frick A, Gustafsson P: 

Research towards Perfected Rail Maintenance 

at Malmbanan, Proceedings: IHHA Conference 

Specialist Technical Session, Calgary/Canada, 

2011 

[6] Meierhofer R, Pohl R: Head Check 

Measurement - a Fully-operational System on 

a Rail Grinder, Proceedings: World Congress 

on Railway Research, Montreal Canada, 2006 

[7] Innotrack – Innovative track systems – 

Results: D4.5.5 Guidelines for Management of 

Rail Grinding, www.innotrack.eu

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