The research work that here is summarized, it is classed on the area of dynamics and measures of railway safety, specifically in the study of the influence of the cross wind on the high-speed trains as well as the study of new mitigation measures like wind breaking structures or wind fences, with optimized shapes.  The work has been developed in the Research Center in Rail Technology (CITEF), and supported by the Universidad Politécnica de Madrid, Spain

Brunel Vázquez, Juan Andrés

Crespo García, Pablo

Sanz Bobi, Juan de Dios

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Adverse aerodynamics effects of a high speed train under the influence of cross winds, analysis and optimization of wind fence

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1 
ADVERSE AERODYNAMICS EFFECTS OF A HIGH SPEED TRAIN 
UNDER THE INFLUENCE OF CROSS WINDS, ANALYSIS AND 
OPTIMIZATION OF WIND FENCE 
Juan de Dios Sanz Bobi, Juan Andrés Brunel Vázquez, Pablo Crespo García 
Research Centre on Railway Technologies (CITEF), Universidad Politécnica de Madrid. 
C/José Gutiérrez Abascal 2 
28006 Madrid. Spain. 
Tel: (+34)913363212. 
juandedios.sanz@upm.es, citef.jabrunel@industriales.upm.es; citef.pcrespo@industriales.upm.es 
 
Abstract 
The research work that here is summarized, it is classed on the area of dynamics and measures of railway safety, 
specifically in the study of the influence of the cross wind on the high-speed trains as well as the study of new 
mitigation measures like wind breaking structures or wind fences, with optimized shapes.  The work has been 
developed in the Research Center in Rail Technology (CITEF), and supported by the Universidad Politécnica de 
Madrid, Spain. 
 
1. INTRODUCTION 
 
1.1. Research background  
 
Due to the high speed increase mileage in the railway traffic and their lightening of the axis weight, is 
increasingly important the effect of the aerodynamic load produced by the cross winds on the trains. These winds 
have a negative effect on the stability of trains travelling at high-speed. They can disturb the normal operation, 
cause damages in the infrastructures or even accidents like derailment or overturning [1]. The train and the 
infrastructures technological development in the last years has magnified the problem, since train speeds have 
increased in a considerable way, and each day the infrastructure development increases the stretch of viaduct and 
on high ground tracks that they increase the pernicious effects of lateral winds.[2]. 
 
This research has focused on the design of actions on the infrastructures that are capable of maintaining the 
speed as high as possible for all the trains running on a line. The main objective of this study is to provide, study 
and evaluate solutions like wind fences of different morphologies, to mitigate the adverse effects of the 
aerodynamic load produced by the wind side on the high-speed trains. The installation of barriers on the sides of 
the railroad tracks is one of the most effective countermeasures and its design is very difficult, because the 
barriers can disrupt the flow of wind causing harmful effects on trains. It is also an expensive measure, and for 
this reason its use is still not very common except in high viaducts. 
 
1.2. Objectives  
 
This article is part of a research study. Previous studies developed [3] were used to evaluate the lateral wind 
effects in order to define the most relevant geometric parameters and make a complete analysis of the effect 
against side winds in different infrastructures. In the work documented in this article are considered the same 
experimental setup. The study aim is to design and to evaluate wind barriers with innovative and optimized 
shapes and morphologies, which solve the problems of the simple barriers. Also, these new proposals of barriers 
have been analyzed in different situations in order to estimate the viability of the solutions based on the 
European’s Technical Specifications for Interoperability [4]. 
 
2. EXPERIMENTAL SETUP 
 
2.1. Description of the environment 
 
The research is focused on the actual conditions, both geographical and operational, of the Madrid-Barcelona 
High-Speed line (Spain). The most affected zones by the cross wind effects have been selected [5] and the two 
high-speed trains that operate in this line have been considered in the study (both can circulate up to 350km/h). 
Infrastructures on which the train runs have also been taken into account: bridges and ground tracks or 
embankment. Also it has been borne in mind both possible emplacements in the double track railroad. 
2 
2.2. Simulation approach. 
 
With two-dimensional analysis and static models, the aerodynamic forces acting on these two vehicles, and the 
improvements achieved in preventing the harmful cross wind effects by means of wind fence have been 
measured. A commercial CFD software (Computer Fluid Dynamics) has been used for this purpose. It allowed 
carrying out a deep analysis of the aerodynamic loads that affect the train in every situation. 
 
The zone in which the analyses have been carried out is a parallelogram of 300 m width and 70 m height, that 
represents a cross section of the railroad track and its surroundings. Figure 1 shows the computational domain 
and the main boundary conditions, there are fixed in base of the European regulations about the matter [6]. 
 
 
Figure 1: Schematic view of the computational domain 
 
To obtain more accurate results, the mesh used is unstructured Figure 2; in zones where the interest for the 
results is greater (zones near the train, the ground and the infrastructure) has done a thinner grid. The grid cells 
are triangular, with the exception of the zone near the train surface. A rectangular grid has been chosen because 
is more precise and regular. In addition, the software allows an enhancement of the grid depending on the zones 
where the gradients (of pressure, of speed, etc.) are greater. This tool has been used in order to adapt the grid and 
refine it. That gives more accurate results in the difficult zones (especially corners of the train). 
 
 
Figure 2: General view of the grid for the embankment case and detail of it around the train. 
 
2.3. Theoretical basics 
 
With the integration of the pressure along the surface of the train the CFD software provides the forces on this 
and with these forces and knowing the wind velocity (a parameter fixed on the basis of the study of the state of 
the art) have been calculated the non-dimensional coefficients for each situations. Due to the fact that they are 
non-dimensional, these coefficients allowed an effective comparison among different situations. The most 
important coefficient for this study is the side force coefficient (Cx), since a study of the lateral train dynamics 
opposite to the strong cross winds is required  
 
 
Figure 3: Displays of pressures contours maps and velocity vectors in two examples 
3 
(Eq. 1) 
Also the pressure contours maps and the velocity vectors were studied. These allow observing the points where 
higher pressures are obtained and to observe the streamlines, both diagrams are very useful graphs for the 
effective design of the barriers Figure 3. 
 
3. SIMULATION AND ANALYSIS 
 
In order to achieve clearly the aims of the study, it has been divided into a first part focused on the design of an 
optimal barrier in all situations studied, and a second part in which we evaluate the feasibility of this best 
solutions obtained. 
 
3.1. Test to optimize the barrier design. 
 
The optimization tests are made to achieve the design of a barrier that is as effective as is possible for the 
protection of both trains on viaduct and on embankment. It is important to look for a balance between the forces 
on the trains placed in the windward track and in the lee track. To take into account these aspects the concept of 
efficacy is described as: 
 
            
       
  
     
 
In this equation (Eq. 1) Co is the value of the drag non dimensional coefficient (lateral affectation coefficient and 
when the barrier height is zero and Ch is the value of Cx (side force coefficient) or Cy (lift coefficient) when the 
train is protected by the barrier that is being compared. This efficacy coefficient allows evaluating the 
improvement in the side and lift affectation that implies the barrier with regard to a situation without barrier. The 
absolute value is considered to evaluate both the affectation in favour of the wind and the affectation caused by 
the depressions between train and barrier that force the trains to counter wind [3]. 
 
Have been simulated situations with 
infrastructure type of embankment and viaduct, 
with different models of train and located in both 
tracks (leeward and windward). It also have done 
simulations with different types and heights of 
barriers and various aerodynamic solutions, such 
bending angles on the top, barriers with hollow 
lower and combinations of both. This made 
possible to compare multiple solutions, and to 
adapt the characteristics of the new devices to the 
specific situations in which higher protection is 
required. Within the multiple aerodynamic 
solutions that have been studied there are two 
that stand out due to its good results:  
 
With the use of railroad outward-oriented 
spoilers, the streamline pass above the train 
placed at the windward track, achieving 
efficiencies similar to those obtained with higher 
barriers. This means that the use of spoilers leads 
to a result as the height of the barrier appears 
greater than it is indeed.  
 
Another solution that gives very good results is 
the addition of lower gaps. These gaps reduce the 
efficiency protection of the barrier on the train of 
windward, but they reduce more drastically the 
vacuum effect that withstands the train placed in 
the lee track to counter wind. Its use together 
with higher barriers gives very good global 
results. 
 
The combination of both solutions, the outward oriented spoilers and the lower gaps, is an alternative barrier 
design which gives excellent overall results in both track and in both infrastructure. 
Figure 4 The barrier on the left side has 1,5m height. with 
spoiler. It is equivalent, in terms of side affectation, to the 
barrier of 1.75 m height (right picture). 
Figure 5: The barrier of the left side is simple of 1.75m. The 
barrier of the right is 2m and has a small gap. This one, 
reduces considerably the depression between the barrier and 
the train (blue areas). 
Figure 6: Displays of velocity vectors for one of the 
simulations. The trains are SIEMENS type, and the barriers 
were the optimum obtained for embankment. 
4 
In the viaduct tests a barrier (Figure 7) was obtained that has a 96% of global efficacy (It takes into account the 
average of the efficacy of the four possible cases, combinations of both trains in both possible situations in the 
double-track). 
 
For the case of embankment three barriers (Figure 7) were obtained that have good global efficacy values but 
none with the level of efficacy obtained in the viaduct case. The situation in viaduct cases is more restrictive, but 
the protection with barriers is more effective. 
 
 
Figure 7: Left: Optimal barrier for the viaduct test. Right: Barriers for the case of embankment. 
 
 
3.2. Feasibility study. 
 
To verify the obtained results a feasibility study was realized. Simulating the situations with the ideal barriers 
obtained with an extreme wind gust velocity of 40m/s, it was calculated, depending on the force on the train 
protected by the barrier, the wind velocity equivalent for this force. The protection with the optimum barriers 
achieves that the wind was equivalent to 11m/s in viaduct and to 14m/s in embankment in the worst of the four 
possible cases. In both infrastructures these values do not suppose a limit in the train speed according to the 
European Technical Specification of Interoperability [3]. 
 
4. CONCLUSIONS 
 
The different morphologies of barriers tested, have allowed compare different solutions, and adapt its way to 
those specific conditions that need more protection, with what has been achieved designs best barriers, who 
minimize the aerodynamic forces on the surface of the train for each of the situations. The results obtained have 
been compared with the experimental information of other studies and projects [7][8]. It has verified that the 
installation of the designed barriers reduce the side affectation of the crosswind up to values that would not 
require, even for extreme wind conditions, restrictions on the train traffic speed.  
 
REFERENCES 
 
[1] Schulte-Werning, B., Gregoire, R., Malfatti, A. and Matschke, G., “TRANSAERO: A European 
Initiative on Transient Aerodynamics for Railway System Optimisation.” Springer, ISBN 3540433163, 
9783540433163. 2002. 
 
[2] Baker, C.J. and Sterling, M., “Current and Recent International Work on Railway Aerodynamics”. 
School of Engineering University of Birmingham. Rail Safety and Standards Board. Issue number 4, August 
11th 2003. 
 
[3] J.D. Sanz, B. Suárez, J. Garzón, J.A. Brunel (2009). “Protection High Speed Trains against lateral wind 
effects”. IMECE 2009-10353. ASME International Mechanical Engineering Congress and Exposition, Lake 
Buena Vista, Florida, USA. 
 
[4] Directive 2004/50/CE. Technical Specification of Interoperability (TSI) on the interoperability of the 
trans-European high-speed rail system. 2004. 
 
[5] Barrado, J. and Lozano, F.J., “Incidencia de los fenómenos meteorológicos sobre la explotación de 
líneas ferroviarias de alta velocidad. Aplicación al tramo Guadalajara- Zaragoza de la nueva línea Madrid- 
Barcelona- frontera francesa”. Fundación de los Ferrocarriles Españoles. Memoria final, pp. 10-11. 2008 
 
[6] UNE- EN 1991-1-4: Eurocode 1: Actions on structures - Part 1-4: General actions - Wind actions  
5 
 
[7] Yun, S.H., Ku, Y.C., Rho, J.H., Ko, T.H., Kwon, H.B. and Lee, D.H.. Numerical Study on the 
Interactions between Rail Vehicle and Wind Fence under Strong Cross Wind -For the Effective Wind Fence 
Design. 7th World Congress on Railway Research. Montréal, Canada, June 4 and June 8, 2006. 
 
[8] Bettle, J., Holloway, A.G.L. and Venart, J.E.S, “A computational study of the aerodynamic forces 
acting on a tractor-trailer vehicle o a bridge on a cross-wind”, Journal of Wind Engineering and Industrial 
Aerodynamics, 91, 573–592. 2003. 


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Adverse aerodynamics effects of a high speed train under the influence of cross winds, analysis and optimization of wind fence

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