Tie Pads Reduce
Life Cycle Costs

Study conirms: Elastic
bedding reduces
track superstructure
deterioration

he increasing rail trafic volumes andhigher vehicle speeds are subjecting
tracks and turnouts to steadily increasingloads. This is in turn causing accelerated
deterioration of the individual track components and higher track maintenance costs.
The fact that tie pads reduce deterioration
on ballast superstructures has already beenshown in calculations as well as long-term
tests on a variety of test sections. Now,
further proof has been provided by a studyconducted on the Austrian national rail
network by the Graz University of Technology.

TAustrian Railways (ÖBB) conducted theirirst tests with tie pads in 1997 to assess
their deterioration-reducing effects on ballast bedding. The results showed a 50 %reduction in track deterioration rates, facilitating at least a 100 % extension of thetamping cycles. Because of these positive
results, Austrian Railways is installing tie
pads on more and more tracks. Under certain conditions1, concrete ties with tie pads

are now the standard solution for mainline
tracks and turnouts2.
1> 33000 total short-tons/day; speeds > 100 mph; tracks withradiuses < 1970 ft. Only one of these three conditions must be met.

2See also ZEVrail 133 (2009) 5 May, pp 180 ff.

The study: Economic Benefits ofTie Pads (WINS)
The aim of the WINS project wasto verify the indings collected in
the various test sections by examining
the entire rail network. “Our measurementson over 1,500 cross sections showed signiicantly improved track geometry in the sections equipped with Sylomer® SLB 3007G

tie pads. This means that the maintenanceintervals can be extended on track sectionswith tie pads, and that the overall service
life of the track superstructure in these
sections will be considerably longer. This
also reduces the costs associated with operational hindrances. These effects signiicantly lower the life cycle costs of the superstructure, even taking the higher investment costs into account”, explained Professor Peter Veit, institute director and faculty
chair at the Institute for Railway Engineering and Transport Economy at Graz University of Technology. Using the results of thestudy, the experts developed a life cycle
costs calculation instrument that can beused to calculate the cost eficiency of a

Economic benefit of Tie Pads –internal rate of return
Internal rate of return [%]According to a study conducted by theGraz University of Technology, the use oftie pads has resulted in improved track
quality throughout the Austrian Railways
network. The findings show that tie pads
reduce deterioration of the ballast, themost critical element in the track
superstructure. The improved track
quality behaviour extends the maintenance intervals and substantially
increase the overall service life of thesuperstructure.

30In relation to curve
radius, traffic load58422 total short tons/
day, track

25
20
15

Additional costs fora padded ties

10520 €30 €32 €

00820

1640

2460

3280

Curve radius [ft]

solution with tie pads. This LCC model offers a statistically sound decision-making
aid for track strategy that takes the speciic
cost structure into account.
Tie Pads offer the greatest
savings on heavily loaded tracks
Tie pads offer the greatest cost savings
when they are installed on track sections
subjected to especially high loads. There we
can ind the biggest economic advantage.
“At a daily trafic load of 77000 total shorttons, we see a static cost reduction of one
third or an internal rate of return of 16 %”,said Stefan Marschnig from LCC rail consult,a research partner of Graz University ofTechnology, summarising the results. Aninternal rate of return3 of 5 % is alreadyachieved at a trafic load of 11000 total
short tons per day. The saving effects ofunder tie pads will be increased further
when considering tracks with tighter curveradii. Individual analyses have shown thatsofter tie pad types like Sylomer® SLS
1308G result in further improvements oftrack quality. “In general, it can be said thattie pads are a technically and economically
proven solution for reducing the total costsof a track superstructure,” said ProfessorPeter Veit, summarising the results of thelife cycle cost study.

3This internal rate of return is based on the additional cost for thepads. In other words, this value indicates at what interest rate the tie
pads refinance themselves, or how fast the positive effects from thepads, such as reduced maintenance expenses and increased service
life, pay for the additional investment. The lower limit of 3.5 % isidentical to the bank rate. Austrian Railways requires a rate of 5 % for
the implementation of innovations. All of these interest rates are realrates, in other words not accounting for inflation.

» Some 980,000 ties
and 350 turnouts with
Getzner pads installedworldwide. «Track quality
Time [years]

30

In relation to trafficload, R > 1970 ft

252015Track quality [MDZ]

Internal rate of return [%]Economic benefit of Tie Pads –Internal rate of return0012345-2.5-5-7.5Additional costs fora padded ties

10520 €
30 €32 €00

11000

33000

22000

44000

55000
66000

-10-12.5-15

77000
88000

Trafic load [total short tons/day, track]

Pad type SLB 3007G
Comparison – unpadded

678

Breakdown of standardised annual costs
Trafic load > 77000 total short-tons/day, straight track
100 %
90 %

All values derived
from static calculations(interest rate 0 %)

80 %
70 %
60 %
50 %
40 %
30 %
20 %

Total LCC
Depreciation
Operational hindrance costs
Maintenance costs

10 %0%
Comparison – unpadded

Pad type SLB 3007G

Long-term tests on sections withextremely high axle loads

T— Tamping intervals extended by at least 100 %— 50 % less track possessions on the line
— Total service life increased by at least 25 %— Less rail corrugation in tight curves— Better track quality, and thus improved comfort— Advantages of timber ties combined with the beneitsof prestressed concrete ties
— Greater contact area between the concrete tie and ballastbed (and up to 90 % less unit pressure on the ballast)— Less ballast settling

The WINS study in brief— The world’s irst statistical proof of the investment return offered bytie pads on the basis of a full rail network analysis incooperation with Austrian Railways— At least a 10 % rate of return on the additional investment— The higher the track load, the more the investment in tie pads pays off

AUSTRIA — Bürs GERMANY — Berlin — Munich FRANCE — Lyon
INDIA — Pune CHINA — Beijing USA — Charlotte

JORDAN — Amman

JAPAN — Tokyo
www.getzner.com

TB LCC US en © Copyright by Getzner Werkstoffe GmbH | 01-2014

Cost reductions through LCC analysishe results of the LCC model conirm
that the return on an investment in tie
pads increases in line with the trafic load.
This implies that installing tie pads would
be an effective way to reduce costs especially on sections with extremely high axle
loads. Getzner Werkstoffe is currently
examining this effect in more detail onlines with 40 short-tons axle loads, andsimilar results are expected from the longterm tests at the Facility for Accelerated
Testing Service in Pueblo, Colorado.