واﻟ واﻟ  ﻟﻠ  اﻟ  اﻟﻬ 
Saudi Standards, Metrology and Quality Org. (SAS O) 
 
     
 
 
 
 
 
Final Draft Standard  
 
 
 
  
SASO /FDS/31832/2020  
  
 
 
 
School buses - Roof strength 
 
   
 
ICS: 43.080.20 
 
This document is a draft Saudi Standard circulated for comments . It is, therefore, 
subject to alteration and modifi cation and may not be referred to as a Saudi 
Standard until approved by SASO . SASO  STANDAR D SASO/FDS 31832/2020
1          
  
Conte nts 
 
1- Scope ............................................................... ............................................................... ....... 2 
 
2- Test conditions ............................................................... ..................................................... 2 
 
3- Technical requirements  ............................................................... ..................................... 2 
 
4- Test procedures  ............................................................... ................................................... 2 
 
5- Results  .............................................................. ............................................................... ..... 3 
 
 
 
Bibliography............................................................... ............................................................. 4  SASO  STANDAR D SASO/FDS 31832/2020
2          
 School buses - Roof strength 
 
1- Scope 
This standard specifies the technical requirements and test pro cedures for the roof strength of 
school bus. 
 
2- Test condi tions 
The following conditions apply to the requirements specified in  item 3. 
2.1 Temperature 
The ambient temperature is any level between 0 °C and 32 °C. 
2.2 Windows and door s 
Bus windows, doors, and emergency exits are in the fully-closed  position, and latched but not 
locked. 
 
3- Technical requirements 
When a force (expressed in Newtons) equal to 1 1/2 times the un loaded vehicle weight 
(in kilograms) multiplied by 9.8 m/sec2 is applied to the roof of the bus body structure through 
a force application plate as specified in test procedures of it em 4 it shall meet the following: 
3.1 The downward vertical movement at any point on the application  plate shall not exceed 
130 mm. 
3.2 Each emergency exit of the bus shall be capable of opening dur ing the full application 
of the force and after release of the force, except that an eme rgency exit located in the roof 
of the bus. 
 
 
4- Test procedures 
Each school bus shall comply with the requirements of item 3, w hen tested in accordance with 
the following procedures: 
4.1 Any non-rigid chassis-to-body mounts replaced with equivalent rigid mounts, 
4.2 Place the bus on a rigid horizont al surface so that the bus is  entirely supported by means of 
the bus frame, and if the bus is constructed without a frame, p lace the bus on its body sills. 
4.3 Remove any components which extend upward from the bus roof. 
4.4 Use a flat, rigid, rectangular force application plate that is  measured with respect to the bus 
roof longitudinal and lateral centerlines, as follows: 
4.4.1  In the case of a bus with a gross axle weight rating (GAWR) of  more than 4,500 kg, 
305 mm shorter than the bus roof and 914 mm wide. 4.4.2  In the case of a bus with a gross axle weight rating (GAWR) of  4,500 kg or less, 
127 mm longer and 127 mm wider than the bus roof. Note: For purposes of these measurements, the bus roof is that structure, seen in the top 
projected 
view, which coincides with the passenger and driver compartment of the bus. SASO  STANDAR D SASO/FDS 31832/2020
3          
 4.5 Position the force application plate on the bus roof so that i ts rigid surface is perpendicular 
to a vertical longitudinal plane and it contacts the roof at no t less than two points, and so that, 
in the top projected view, its longitudinal centerline coincide s with the longitudinal centerline 
of the bus, and its front and rear edges are an equal distance inside the front and rear edges of 
the bus roof at the centerline. 
4.6 Apply an evenly-distributed vertical force in the downward direction to the force applicati on 
plate at any rate not more than 13 mm per second, until a force  of 2,224 N has been applied. 
4.7 Apply additional vertical force in the downward direction to t he force application plate at a 
rate of not more than 13 mm per second until the force specifie d in item 3. 
 
 
5- Result 
5.1 Measure the downward movement of any point on the force applic ation plate, which 
occurred during the application of force in accordance with ite m 4.7. 
5.2 To test the capability of the vehicle's emergency exits to ope n in accordance with item 3.2. 
5.2.1  In the case of testing under the full application of force, op en the emergency exits while 
maintaining the force applied in accordance with item 4.6 and i tem 4.7. 
5.2.2  In the case of testing after the release of all force, release  all downward force applied to 
the force application plate and open the emergency exits. SASO  STANDAR D SASO/FDS 31832/2020
4          
  
Bibliography  
 
 [1] 49 Subtitle B-Chapter V-Part 571-Subpart B Section 220 (FMVSS 571.220).  
(FMVSS 571.220) "School bus rollover protection".