CEN/TR 17420:2020

SLOVENSKI STANDARD
01-marec-2020
Železniške naprave - Zunanja konstrukcija tramvajskih in lahkih železniških vozil
glede na varnost pešcev
Railway applications - Vehicle end design for trams and light rail vehicles with respect to
pedestrian safety
Bahnwendungen â Fahrzeugkopfgestaltung von StraÃen- und Stadtbahnen im Hinblick
auf den Passantenschutz
Applications ferroviaires - Conception de l'extrémité des véhicules pour tramways et
métros légers en ce qui concerne la sécurité des piétons
Ta slovenski standard je istoveten z: CEN/TR 17420:2020
ICS:
45.140 Oprema za podzemne vlake, Metro, tram and light rail
tramvaje in lahka tirna vozila equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEN/TR 17420
TECHNICAL REPORT
RAPPORT TECHNIQUE
January 2020
TECHNISCHER BERICHT
ICS 45.060.10; 45.140
English Version
Railway applications - Vehicle end design for trams and
light rail vehicles with respect to pedestrian safety
Applications ferroviaires - Conception de l'extrémité Bahnanwendungen - Fahrzeugkopfgestaltung von
des véhicules pour tramways et véhicule ferroviaire Straßenbahnen und Light rail Fahrzeugen im Hinblick
léger en ce qui concerne la sécurité des piétons auf den Passantenschutz

This Technical Report was approved by CEN on 23 September 2019. It has been drawn up by the Technical Committee CEN/TC
256.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 17420:2020 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
1 Scope . 3
2 Normative references . 4
3 Terms and definitions . 5
4 Symbols and abbreviations . 7
5 Front end design of tram vehicles and light rail vehicles . 7
6 Reference collision scenario type A. 8
7 Reference collision scenario type B. 18
Annex A (informative) PACM test protocol report . 24
Bibliography . 30

European foreword
This document (CEN/TR 17420:2020) has been prepared by Technical Committee CEN/TC 256 “Railway
applications”, the secretariat of which is held by DIN.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
1 Scope
This technical report is applicable to tram vehicles according to EN 17343 . Tram-Train vehicles, on track
machines, infrastructure inspection vehicles and road-rail machines according to EN 17343 and
demountable machines/machinery are not in the scope of this technical report.
This technical report describes passive safety measures to reduce the consequences of collisions with
pedestrians. These measures provide the last means of protection when all other possibilities of
preventing an accident have failed, i.e.:
— design recommendations for the vehicle front to minimize the impact effect on a pedestrian when
hit,
— design recommendations for the vehicle front end for side (lateral) deflections in order to minimize
the risk of being drawn under the vehicle on flat ground (embedded track),
— design recommendations for the vehicle body underframe to not aggravate injuries to a
pedestrian/body lying on the ground,
— recommendations to prevent the pedestrian from being over-run by the leading wheels of the
vehicle.
The following measures to actively improve safety are not in the scope of this technical report:
— colour of front;
— additional position lights;
— additional cameras;
— driver assistance systems;
— additional acoustic warning devices, etc.;
— view of the driver / mirrors;
— consequences for pedestrian injuries due to secondary impact with infrastructure (side posts,
concrete ground, poles, trees, etc.).
The recommendations of this technical report only apply to new vehicles.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 15663:2017+A1:2018, Railway applications – Vehicle reference masses

Under preparation. Stage at the time of publication: prEN 17343.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
3.1
tram vehicle
urban rail vehicle designed to run on a tram network
[SOURCE: EN 17343:— , 3.1.6.1.2.3]
3.2
collision scenario
collision scenario derived from accident analysis that is applicable for design and assessment
3.3
head injury criterion
HIC
measure of the likelihood of head injury stemming from impact or acceleration
Note 1 to entry: The head injury criterion (HIC) should not exceed a value of 1 000 over any time interval of up
to 15 ms. The HIC is calculated using the following formula:
25,
t

A dt

R
∫
t

HIC t− t
( )
2 1

tt−
( )
2 1


where
t1 represents the start of the time interval,
t represents the end of the time interval,
HIC is the maximum value of HIC for (t – t ) ≤ 15 ms,
2 1
A is the resultant acceleration
R
2 22
A A++A A
R XY Z
where
A , A and A represent the accelerations in g in X, Y and Z directions.
X Y Z
Note 2 to entry: The 15 ms time frame relates to the original biomechanical testing used to establish the HIC as
an injury criterion commonly accepted for impacts against fixed surfaces.
Note 3 to entry: This criterion can be used to assess the safety regarding vehicles, personal protective gear and
sports equipment.
=
=
3.4
light rail vehicle
urban rail vehicle designed to be line of sight operated and/or to be operated on segregated lines by
signalization
Note 1 to entry: German: Light-Rail-Fahrzeug.
Note 2 to entry: Light rail vehicle is a generic term used to distinguish a vehicle from heavy rail vehicles.
[SOURCE: EN 17343:—, 3.1.6.1.2.1, modified — The end of the original definition "signal-controlled
segregated lines" was replaced with "segregated lines by signalization" and Note 1 to entry" was added.]
3.5
tram system
urban rail system operated on infrastructure shared with road traffic and/or its own infrastructure
[SOURCE: EN 17343:—, 3.1.2.2, modified — The original Notes to the definition were not reproduced
here.]
3.6
rescue mannequin
life size model of a person used in tests to simulate what happens to people when a vehicle gets into an
accident (with a pedestrian)
3.7
anthropomorphic test device
ATD
model or mannequin of a person used in tests
3.8
pedestrian
walking, standing or lying person
Note 1 to entry: In this context, person can refer to an adult or a child.
Note 2 to entry: Any recommendations defined in this document for walking or standing persons will also
improve the impact effect on cyclists (self-propelled or on e-bikes), skaters, persons in wheel chairs, or children in
baby buggies, etc. Persons on e-scooters, motorbikes, etc. are not considered.
3.9
pedestrian deflector
technical device that pushes the pedestrian out of the path of the tramway in case of a collision
3.10
pedestrian anti-crush mechanism
PACM
mechanism like a trap basket / drop down tray
3.11
front cover
front fairings
outside front panels of the tram vehicle structure below the windscreen, i.e. streamlining
3.12
tram-train vehicle
vehicle designed to operate on urban and/or regional networks, in track-sharing operation and
interfacing with road traffic
[SOURCE: EN 17343:—, 3.1.6.1.3, modified — The current definition was substantially reworded.]
3.13
tram width
TW
overall width of the car body excluding additionally fixed equipment like mirrors and cameras
4 Symbols and abbreviations
ATD Anthropomorphic Test Device
IIV Infrastructure Inspection Vehicle
LRV Light Rail Vehicle
OTM On-Track Machine
PACM Pedestrian Anti-Crush Mechanism (fr: dispositif anti-écrasement d'un piéton (DAEP))
5 Front end design of tram vehicles and light rail vehicles
5.1 Objective / concept
The objectives of this technical report are to provide protection for pedestrians by reducing the risk of
severe injuries, of being trapped under the vehicle, of being hit by underfloor equipment, and of being
run over by the wheels of the vehicle. All tram vehicles and light rail vehicles should have a design that
enables a pedestrian’s body to be deflected rather than be run over during an impact. The pedestrian is
considered to have been deflected onto the side once the pedestrian has been moved out of the path of
the vehicle.
5.2 Sequence of an impact
The entire sequence of an impact can be divided into three phases. All three phases can cause severe
injuries to the involved pedestrian:
— Phase 1 is considered as primary impact. A pedestrian, standing or walking in front of a moving tram,
comes in contact with the vehicles front end. It is assumed that the pedestrian is moving
perpendicular to the direction of the tram. Consequently, the tram hits the pedestrian at his side.
— Phase 2 is considered as secondary impact. Once being hit by the tram the pedestrian is thrown
forward or to the side. As a consequence, the pedestrian impacts on the infrastructure (e.g. pavement,
track, side poles).
— Phase 3 is considered as tertiary impact. As a consequence of Phase 2 the pedestrian might lay on the
track, be overrun by the tram and collide again with the lower parts of the tram.
This technical report focuses on the consequences of the primary and tertiary impact. The consequences
of a secondary impact are out of the scope of this technical report. Due to the recommendations given in
this technical report, the consequences for the pedestrian in the primary impact and the risk to be run
over by the wheels of the vehicle should be minimized (see 7.3).
5.3 Reference collision scenarios
The following reference collision scenarios with pedestrians should be considered:
— Type A: Collision with a passing pedestrian in the front area of the vehicle;
— Type B: Collision with a lying pedestrian on the ground in front of the vehicle.
Collision type A covers the effects of a primary impact and influences the effects of the downstream
phases.
The tertiary impact is regarded to be identical to the collision type B.
6 Reference collision scenario type A
6.1 Introduction
The general approach is to achieve compliance with the geometrical requirements defined in 6.3.
If it is not possible to comply with all geometric parameters, numerical simulations can be carried out to
demonstrate the ability to limit the risk of severe injuries and to encourage lateral ejection. Nevertheless,
the criteria for h in the impact surface and for the avoidance of sharp edges in the extended impact zone
s
should still be fulfilled in this case (from 6.3).
The recommendations of this section focus on the side impact against a pedestrian at the front end (i.e.
passing pedestrian). Two categories of pedestrians are identified:
— a 6-year-old child, 1,10 m in height;
th
— a medium-sized adult, 1,75 m in height (50 percentile/average size).
If the requirements are fulfilled for these two categories, the design characteristics of the front end will
also be beneficial to the impact effect in collisions with other sizes of pedestrians.
6.2 Impact surfaces
6.2.1 General
The impact surface is part of the front face of a tram predestined for contact with pedestrians in case of a
collision and with the most likely possibility of severe injuries. This region should be used for evaluation
of the geometric requirements. The impact surface is divided into two zones:
— centre zone;
— intermediate zone.
The impact surface is defined as the front surface of the tram up to a height of 1,75 m from the ground
(the average height of an adult). The width of the impact surface is 50 % of the maximum tram width
centred to the tram centre line (see Figure 1),
The projection surface from the front view is used to define the impact surface.
Based on the current requirements for visibility the impact surface is not assumed to interfere with the
A-pillars of the tram front. If the impact surface overlaps the A-pillars nevertheless, then the impact
surface may be reduced to the width between the A-pillars at a height of 1,75 m from the ground, minus
100 mm on each side.
6.2.2 Extended impact surface
The extended impact surface is defined in analogy to the impact surface with the exception that the width
is 75 % of the maximum tram width.
The impact surface is displayed in Figure 1:

Figure 1 — Impact surface
6.3 Geometric criteria to reduce the severity of injuries
6.3.1 General
If the compliance with the geometric recommendations given in this chapter is proven, the HIC value is
assumed to stay below 1 000. In this case, any additional numerical analyses (according to 6.4) for this
proof are not mandatory but monitoring of this value is recommended.
6.3.2 Objective of the desired kinematics
In order to limit severe injuries, in particular to the head, the body kinematic to be favoured is either to
block the shoulder and the torso as quickly as possible while limiting the rotation of the torso or to
progressively impact-the pedestrian starting from the lower legs up to the torso and shoulders.
All trams and light rail vehicles should have a design that enables a body to be deflected rather than be
run over in an accident. The objective is to limit the risk of intrusion of a pedestrian, including a child,
under the tram.
6.3.3 Definition of evaluation points
The criteria mentioned are defined to ensure a lateral deflection of a body in case of collision with a
pedestrian. Additionally, the risk of fatal head injury at all points of the potential impact surface is reduced
(criterion: HIC ≤ 1 000). Figure 2 shows the entire width of the tram and the angle α of tangents at the
front in height of the foremost points below z = 1,75 m to ensure an efficient deflection to the side.
The values of the geometric parameters at the specific points should be measured to ensure compliance
with the criteria. In case of a symmetrical tram, regarding the XZ plane, the values may be measured for
one half only.
Figure 2 — Definition of evaluation points
6.3.4 Geometric parameter definition
The parameters β and d should be applied at all points on the impact surface.
f
The following geometric parameters are taken into account:
Figure 3 — Side view of vehicle front (projection to cutting plane parallel to XZ plane)
The parameters in Figure 1 to Figure 3 are defined in the following table:
Table 1 — Definitions of geometric parameters for Figure 1 to Figure 3
Parameter Definition
h h is determined by cutting the impact surface with planes parallel to the XZ plane.
s s
h corresponds to the height of the foremost points of these intersection curves (e.g. the
s
Z coordinate of the maximum X abscissa point).
h is determined for the vehicle in design mass in running working order according to
S
EN 15663:2017+A1:2018, Table 5 (based on EN 15663).

α The h points and also the foremost points below z = 1,75 m within the complete width
s
of the tram are combined with a curve and projected to the XY plane, α is the angle
between the y-axis and the tangent to the projected curve.
Line B Line B is defined by the point h and the upper point of the impact surface of the
s
corresponding cutting plane (parallel to XZ plane) at a height of 1,75 m (see Figure 3).
β The angle β defines the inclination of line B versus the Z axis (β ≥ 10°)
d d defines the tolerance band centred by line B and marked by two lines parallel to line
f f
B with a distance of d /2. Any front geometries in the impact surface should lie within
f
this tolerance band (d = 250 mm), measured horizontally. d should be minimized.
f f
g ground clearance - refer to 7.2
c
NOTE 1 An intersection curve with a vertical slope at the maximum abscissa point gives several values of
h (see 6.3.5.2).
s
NOTE 2 Different values of Y can give different values for h (see 6.3.5.2).
s
6.3.5 Evaluation criteria for impact surface
6.3.5.1 Criterion for angle α
The angle α should be continuously increased by growing lateral coordinate (y-axis).
The criterion for angle α depends on the lateral position of the evaluation point (see Figure 2: ignoring
transitions and blending):
— Centre zone of impact surface: Surface at the centre of the front end (15 % range of the tram width
in the centre - see Figure 2) should be curved (in order to take into account any design constraints).
This width represents the side-on envelope of a regular-sized human. From the transition point to
the intermediate zone, the angle α should be equal to or more than 15°.
— Intermediate zone of impact surface (lateral position between centre zone (15 % range of the tram
width) and a lateral position of the ± 50 % value of half of the tram width measured from the centre
line): The angle α should be continuously increased to reach equal or more than 30° from the
transition point to the extended impact zone.
— Extended impact surface (lateral position between 50 % and 75 %): The angle α should be
continuously increased (ignoring transitions and blending) from 30° to reach equal or more than 60°.
6.3.5.2 Criterion for h
s
In the impact surface the curve of the most protruding points of the impact area (curve of the h points)
s
should have the lowest Z coordinates possible in order to hit an adult pedestrian below the knees:
h ≤ 350 mm (see also 6.3.4).
s
If there are several values for h , the lowest h value should be considered/assumed.
s s
6.3.5.3 Criterion for angle β
The angle β should be ≥ 10° over the whole width of the impact surface.
6.3.6 Guiding procedure
The evaluation should be performed according to the following steps:
1) Define the impact surface;
2) Project the front surface to the ground plane (XY) to determine the foremost boundary line for h
s
and α determination;
3) Determine the evaluation points, e.g. different Y-values for the cutting planes – the evaluation points
should cover the extremities of the impact surface;
4) Determine the values for the angle α in the evaluation points and check the criteria for angle α;
5) Sketch line B in the different cutting planes;
6) Determine d and check the criteria;
f
7) Determine β and check the criteria.
If these criteria are not met, numerical analyses with ATD models should be carried out to prove
compliance with the criteria or the front design has to be adapted.
6.3.7 Front end geometry
6.3.7.1 Sharp edges and protruding parts
All exposed rigid edges on the extended impact surface (75 % of tram width) and up to a height of
1 750 mm should have radius of at least 10 mm. An edge is considered as exposed only if it can be
contacted by a sphere of 100 mm diameter. In case of pillars that widen towards the top, the requirement
for the absence of sharp ends is valid for the entire range of the impact and extended impact surface
(including the A-pillars).
Any gaps between skirts should be as small as possible. The surface of the A-pillar and/or its cover layer
should be as soft as possible.
Sharp edges should be avoided or covered, e.g. windscreen wiper motor output shaft. Windscreen wiper
arms and blades are excluded. They are considered to be flexible. A rigid edge should be considered to be
one using material with a Shore A hardness greater than 50. For exposed rigid external edges, where the
edge projects not more than 3,2 mm from the adjacent surfaces, the requirements for minimum radii
should not apply, provided that the height of the pr
...