الهيئة السعودية للمواصفات والمقاييس والجودة  
Saudi Standards, Metrology and Quality Org (SASO)  
 
  
  
  
  
 
  
  
SASO/CD 32182 (A)  
  
  
  
  
السيارات- حواجز الحماية الخلفية للشاحنات والمقطورات  
Motor vehicles -Rear Under Run Protective Devices for Truck 
and Trailer  
   
   
 
 
 
 
 
 
 
 
 
 
   
   
   
ICS:  43.040.60  
 
THIS DOCUMENT IS A DRAFT  SASO STANDARD CIRCULATED FOR 
COMMENT. IT IS, THEREFORE SUBJECT TO CHANGE AND MAY 
NOT BE REFERRED TO AS A SASO STANDARD UNTIL APPROVED 
BY THE BOARD OF DIRECTORSSASO STANDARD   SASO…..:2021  
  
 
  1     مقدمة 
قامت بالهيئة السعودية للمواصفات والمقاييس والجودة بإعداد مشروع المواصفة القياسية السعودية " 
السيارات - حواجز الحماية الخلفية للشاحنات والمقطورات " عن طريق الفريق الفني لمركبات الطرق   بعد 
استعراض المواصفات القياسية العربية والأجنبية والدولية والمؤلفات المرجعية ذات الصلة على أن تلغي 
هذه المواصفة القياسية السعودية. SASO GSO 2114:2011 
 
Foreword 
The Saudi Standards, Metrology and Quality Organization (SASO) has 
prepared the draft of  Saudi Standard " Motor vehicles -Rear Under Run 
Protective Devices for Truck and Trailer " by technical  committee  of road 
vehicle  based on relevant ADMO, International and National foreign 
Standards and references. These standards will be  replace SASO GSO 
2114:2011.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 SASO STANDARD   SASO…..:2021  
  
 
  2 Motor Vehicles - Rear Underrun Protection Devices  for T ruck and Trailer  
  
1- SCOPE AND FIELD OF APPLICATION  
This standard is concerned with the requirements for the rear underrun protective 
devices (RUPD) of o vehicles of categories N2, N3, O3 and O4 (1); This standard 
does not apply to Traction units for articulated vehicles, special trailers constructed 
for the carriage of very long loads such as timber, steel bars etc  and vehicles where 
any RUPD is incompat ible with their use.   
2-  COMPLEMENTARY REFERENCES  
2.1  SASO  469 “Motor Vehicles - Weights and Dimensions”.  
2-2              SASO Technical Regulation for Front, Rear and Side Barriers for Trucks and  
Trailers.    
3-   DEFINITIONS  
3.1  Unladen mass:  The mass of the vehicle in running order, unoccupied, and unladen 
but complete with fuel, coolant, lubricant, tools and spare wheel.  
3.2  Maximum mass: The mass stated by the vehicle manufacturer to be technically 
permissible.  
3.3  Rear underrun protective d evice (RUPD): It consists of a cross -member and links 
to the chassis side members or other structural members of the vehicle.  
3.4  Type of RUPD: means RUPD which do not differ with respect to the essential 
characteristics such as shape, dimensions, attach ment, materials and the marking s 
cited for  a sample of the type of RUPD as: the sample shall be clearly and indelibly 
marked on all its main components with the applicant's trade name or mark and the 
type designation.  
3.5 Rear Underrun Protection (RUP) : The presence at the rear of the vehicle of  either: 
a special RUPD or a body work, chassis parts or other components such that by 
virtue of their shape and characteristics, these elements can be regarded as totally 
or parti ally fulfilling the function of the RUPD.  
3.6              The definitions in SASO Technical Regulation for Front, Rear and Side Barriers for 
Trucks and Trailers . 
 
ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ  
1)  N2: Vehicles use d for the carriage of goods and having a maximum mass exceeding 3.5 tonnes but not exceeding 12    
tonnes. (Commercial Truck)  
N3: Vehicles used for the carriage of goods and having a maximum mass exceeding 12 tonnes. (Commercial Truck)  
O3: Trailers  (including semi –trailers)  with a maximum mass exceeding 3.5 tonnes, but not exceeding 10 tonnes  
O4: Trailers  (including semi –trailers)  with a maximum mass exceeding 10 tonnes 
 SASO STANDARD   SASO…..:2021  
  
 
  3 4-  REQUIREMENTS  
  The following shall be met:  
4.1  General  
4.1.1  All vehicles carrying goods, including tankers, mobile cranes, mobile workshops, 
trailers and semi -trailers shall be equipped with rear underrun protective devices to 
protect against underrunning of vehicles in the event of rear collision with passenger 
cars, multi -purpose vehicles and light duty trucks having a maximum mass not 
exceeding 3.5 tonnes.  
4.1.2  The rear underrun protective device shall comply with the requirements specified 
in item 4.2  to 4.6.  
4.1.3  If the vehicle is so designed and equipped at the rear that by virtue of their shape 
and characteristics, its component parts comply with the requirements specified in 
items 4.5 and  4.6, then the vehicle may not be necessary to be provided with rear 
underrun protective device.  
4.1.4  The maximum m ass of a vehicle type for which the rear underrun protective device 
to be installed shall not exceed the value indicated on the rear underrun protective 
device for which it is designed for.  
4.2 Material  
4.2.1 The mechanical properties of the underrun protective device's material shall be 
either hot rolled high strength Steel with a minimum yield strength of 350 N/mm2 
and minimum tensile strength of 480 N/mm2 or high strength Aluminum Alloy with 
a minimum yield strength of 350 N/mm2 and minimum tensile strength of 480 
N/mm2. 
4.2.2 The minimum mechanical properties of bolts should be made of Low -carbon 
martensite with 10.9 class bolt with minimum proof strength of 830  N/mm2, 
minimum yield strength of 940 N/mm2 and minimum tensile strength of 1040  N/mm2. 
4.3 Welding  
4.3.1  Welding could only use between the UPD and the bridge/support. It is strictly 
prohibited to weld the UPD or the bridge/support to the chassis of the truck or 
trailer.  
4.3.2  Welding should be fully welded. ( Figure  1) 
4.3.3  Welding thickness  (h) should be compatible between the bridge/support and the 
UPD. ( Figure  2) 
4.3.4  The minimum requirements for the welder wire's material used in welding is AWS 
electrode number (E90xx), with minimum yield strength of 531N/mm2 and 
minimum tensile strength  of 620 N/mm2. 
4.4 The retro -reflective marking (Tape)  
4.4.1  The retro -reflective marking (Tape) should be on the UPD, so that it can be seen at 
night or when the visibility is not clear.  (Figure  3) SASO STANDARD   SASO…..:2021  
  
 
  4 4.4.2 The retro -reflective marking (Tape) should be yellow. The width of a rear tape 
material shall be 10 0 mm, with tolerance +2 mm. It should be complied with the 
Saudi Standard (SASO 2913).  
4.5  RUPD Technical requirement  
4.5.1 The section height of the RUPD member shall not be less than 100 mm . (Figure 9)   
4.5.2  The lateral extremities of the cross -member shall not bend to the rear or shall not 
have a sharp outer edge. This requirement can be considered as complied if the 
lateral extremities of the cross member are rounded on the outside and have a rad ius 
of curvature of not less than 2.5mm. (Figure 4) 
4.5.3  In case, if the rear underrun protective device is designed to have several positions 
at the rear of the vehicle, there must be a guaranteed method of securing it in the 
service position, and the force applied by the operator to vary the position of the 
device shall not exceed 40 daN  (400N) .  
4.5.4  For vehicles fitted with a platform lift at the rear, the underrun device may be 
interrupted for the purposes of the mechanism. In this case, the follo wing special 
requirements apply:  
 4.5.4.1 The maximum lateral clearance measured between the elements of the underrun 
device and the elements of the platform lift, which move through the interruption 
when the lift is operated and which make the interrupti on necessary, may amount 
to no more than 2.5 cm.  
 4.5.4.2 The individual elements of the underrun protection, including those outboard of the 
lift mechanism, where provided, must have an effective surface area, in each case, 
of at least 350 cm2 (Figure 5 ). However, in the case of vehicles having a width of 
less than 2000 mm and where it is impossible to achieve the above requirement, the 
effective surface may be reduced on the condition that the resistance criteria are 
met.  
4.6  Installation of RUPD indicated in item 4.5 to the vehicle  
4.6.1  The ground clearance with respect to the underside of the protective device, even 
when the vehicle is unladen shall not exceed 450 mm over its entire width. (Figure 4) 
4.6.2  For the trucks , trailers  and tow trucks  with a weight exceeds 3 tonnes , the ground 
clearance with respect to the underside of the protective device, even when the vehicle 
is unladen, shall not exceed 450 mm , and the horizontal distance between the rear of 
the device and the rear extremity of the  vehicle,  shall not exceed 400 mm  for 
departure angle 8 °. (Figure 6) 
4.6.3  For departure angle condition that does not met 8°, a movable protective device shall 
be installed  which has the ability to be lifted forward or backward as shown in (Figure  
7), or has the ability to slide up or down as shown in (Figure  8) 
4.6.4  The width of the rear underrun protective device shall not at any point exceed the 
width of the rear axle m easured at the outermost points of the wheels.  SASO STANDARD   SASO…..:2021  
  
 
  5 4.6.5  The width of the rear protective device shall not be more than 100 mm shorter on 
either side than the width of the rear axle measured at the outermost points of the 
wheels. (Figure 4) 
4.6.6  The maximum mass of vehicle type for which the RUPD is installed shall not 
exceed the value indicated on the RUPD or with the approved document.  
5-  MARKING  
5.1  The marking shall be comply with SASO technical regulation forTechnical 
regulation for front , rear and Lateral Underrun Protective Devices for Trucks and 
Trailers.  
 
6-  DIMENSION SPECIFICATIONS  
6.1  Measuring instruments  
6.1.1  Dimension measuring instrument  
  The instruments used shall permit measurement to an accuracy of ( ± 1) mm.  
6.2 Approval Dimension Specifications  
 The following Dimension specifications design for rear underrun protective devices 
shall be followed at Annex 1.  
7-  CRITERIA OF TECHNICAL CONFORMITY  
7.1  The rear underrun protective device shall be considered complying  with all the 
requirements of this standard when the withdrawn sample from the consignment or 
the supplied sample by the manufacturer, otherwise the rear underrun protective 
device shall be considered noncomplying.  
  
  SASO STANDARD   SASO…..:2021  
  
 
  6  
  
 
Knowing that (h) means welding thickness.  
 
Figure  1: Approved welding shape  
  
SASO STANDARD   SASO…..:2021  
  
 
  7  
 
 
Where, h (welding thickness), t c (thickness of the bridge or support) and t h(thickness of 
the UPD)  
Figure  2: Correct methods followed in welding  
 
 
 
Figure  3: The way of installing the Retro -Reflective tape on the rear underrun protective 
device of a truck  
  
 
    
  
tc > h & th > h 
Not a correct welding  tc < h & th < h  
Not a correct welding  tc = h  & th = h when th = tc   
tc > h  & th = h when tc > th 
SASO STANDARD   SASO…..:2021  
  
 
  8  
 
Figure 4 : Rear view of a truck shown technical specifications of RUPD  
 
 
Figure 5 : Rear view of a truck with load lifting platform indicating technical specifications of 
RUPDs  
  
SASO STANDARD   SASO…..:2021  
  
 
  9  
Figure 6: The horizontal distance between the rear of the device and the rear extremity of the  
vehicle for  departure angle 8°  
 
 
 
Figure 7: Movable proactive device (Forward and backward) for departure angle condition 
that does not met 8°  
SASO STANDARD   SASO…..:2021  
  
 
  10  
Figure 8: Movable proactive device (sliding) for departure angle condition that does not met 8°  
 
 
  
SASO STANDARD   SASO…..:2021  
  
 
  11 Annex 1  
Approval Dimension  and materials  Specifications  
1. The following Dimension  and materials  specifications design for rear underrun 
protective devices shall be followed .  
1.1  Visual inspection   
  The rear underrun protective device shall be visually examined to check for exact 
dimensions, bolts type, welding standard, any damage, crack, sharp outer edge, and 
any apparent defects.  
1.2 The mechanical properties of the underrun protective device's material s hall be as 
follows:  
 
 
 
 
1.3 General Dimensions of RUPD  
1.3.1 The main cross -section area for the RUPD are shown in Figure 6 . 
 
Figure 9: Main cross -sectional area models of RUPD  
 
1.3.2 Dimensions of the cross -sectional area  
For trucks and trailers with a weight exceeding 3.5 tones.  
 
 
 
Table 1 
 
Material Used  Type  Min. Yield 
Strength  Min. Tensile 
Strength  
Steel  Hot Rolled  350 N/mm2 480 N/mm2 
Aluminum Alloy  (Al-Cu Alloy)  350 N/mm2 480 N/mm2 
Model Cross -sectional Area  D (mm)  B (mm)  C (mm)  minimum t (mm)  
C- section  100 50 20 5 
Rectangle section  100 50 -------  5 
Circle section  100 -------  -------  5 SASO STANDARD   SASO…..:2021  
  
 
  12 1.3.3 Different Main Models of RUPDs  
1.3.3.1 A Model of RUPD . 
It consists of RUPD and the carrier bridge that connects the RUPD to the truck 
chassis as in Figure 7 .  
 
Figure 10: Model of RUPD for a truck or trailer  
Location at where the RUPDs attached to the carrier bridges  
 
 
Figure 11:  Front view showing the position of installing the RUPD to the carrier bridge  
 
A table clarifying the position of installing RUPD to the carrier bridge.  
Table 2 
 
Type of Material  L (mm)  W (mm)  
Optional to add a support 
between bridge and FUPD  W (mm)  
Must add a support between 
bridge and FUPD  
Steel 700-1200  Less or equal 400 Over 400 
Aluminum Alloy 700-1200  Less or equal 400 Over 400 
 
 
 
 SASO STANDARD   SASO…..:2021  
  
 
  13 1.3.3.2  Carrier Bridge Connecting RUPD to Truck or Trailer Chassis  
When a truck or trailer has a chassis of (I -section beam), the type used for  the 
carrier bridges is:  
 
Figure 12: Sample of a carrier bridge used with (I -section beam) chassis truck or trailer  
 
When a truck or trailer has a chassis of (C -section beam), the type used for the 
carrier bridges is:  
 
 
Figure 13: Sample of a carrier bridge used with (C -section beam) chassis truck or 
trailer  
 
1.3.3.3  Adding Support to Carrier Bridge between RUPD and Truck or Trailer Chassis  
 
In case the distance after installing the RUPD to the carrier bridge known as (W), 
exceeds 400mm, a rear support should be added to the bumper as in Figure 11. 
Note that the beam is installed between the carrier bridge and the RUPD outer 
edges.  
SASO STANDARD   SASO…..:2021  
  
 
  14  
Figure 1 4: A supporter is installed between the RUPD and carrier bridge when distance, 
known as (W), exceeds 400mm.  
 
1.3.3.4  Connecting RUPD Parts  
 
Connection can be done by welding or using bolts.  For bolts, they should be as 
follows:  
Trucks with a weight less  than 12 tones 
Trailers with a weight less than 10 tones  Trucks with a weight exceed 12 tones 
Trailers with a weight exceed 10 tones  
Number of 
Bolts  Bolt Diameter (mm)  Number of 
Bolts  Bolt Diameter (mm)  
4 16 4 18 
5 14 5 16 
6 13 6 15 
7 12 7 14 
8 11 8 13 
9 10 9 12 
Table 3 
 
 
 
 
 
 
 SASO STANDARD   SASO…..:2021  
  
 
  15 1.3.3.5 Models of RUPDs for Truck and Trailer  
 
 
Figure 1 5: Models of truck and trailer RUPDs  
 
1.3.3.6 For further details, see (Annex 2 and 3).   
 
 
 
 
 
 SASO STANDARD   SASO…..:2021  
  
 
  16 Annex 2 
Sample Models of RUPDs in Truck  
 SASO STANDARD   SASO…..:2021  
  
 
  17   
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  18   
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  19   
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  20  
SASO STANDARD   SASO…..:2021  
  
 
  21   
SASO STANDARD   SASO…..:2021  
  
 
  22 Annex 3 
Models of Carrier Bridges and Supporters used in Connecting UPD to Chassis . 
*Dimensions in this Figure  represent overall view in mm, and may differ from one truck or trailer to another.  
SASO STANDARD   SASO…..:2021  
  
 
  23 *Dimensions in this Figure  represent overall view in mm, and may differ from one truck or trailer to another.  
SASO STANDARD   SASO…..:2021  
  
 
  24 *Dimensions in this Figure  represent overall view in mm, and may differ from one truck or trailer to another.  
SASO STANDARD   SASO…..:2021  
  
 
  25 *Dimensions in this Figure  represent overall view in mm, a nd may differ from one truck or trailer to another.  
SASO STANDARD   SASO…..:2021  
  
 
  26 *Dimensions in this Figure  represent overall view in mm, and may differ from one truck or trailer to another.  
SASO STANDARD   SASO…..:2021  
  
 
  27  *Dimensions in this Figure  represent overall view in mm, and may differ from one truck or  trailer to a