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Bus design & safetyACCORDING TO SPECIFIC KENYAN REQUIREMENTS:
LEGAL BACKGROUND (The Traffic Act & KEBS bus standard), AVAILABILITY OF MATERIALS & TECHNOLOGIES,
ROAD CONDITIONS
PROTECTOR – superior design from KVM Ltd.
Guide lines for Design:
Passenger safetyStaff safetyTraffic safetyFunctionalityAerodynamicErgonomy = Comfort
“Never design appearance only”Presented by Ralph Hruschka MSc.
Inventor & Consultant at KVM Ltd.
PROTECTOR-superior design from KVM Ltd.
Safety critical features1) Roll over protection, 2) Front impact protection, 3)Side impact protection, 4) Passenger door, 5) Door
hinge cover, 6) Passenger seats, 7) Seat mounting, 8) Front grille, 9) Gangway, 10) Cross members, 11) Side wall diagonals, 12) X-Members, 13) Door grab handles, 14) Uppermost stair, 15) Door locking
mechanism, 16) Front bumper, 17) Rear bumper, 18)Rear overhang, 19) Rear glass / emergency exit
Moto: Every feature that will save a life must be realized
2
Case 1: Roll over accidents
PROTECTOR-superior design from KVM Ltd.
Roof collapsed and disintegrated without safety concept
3
Roll over protection• To reinforce the strength in between side walls and the roof • Prevention of a passenger cabin collapse sideward
Gussets
Diagonals
PROTECTOR-superior design from KVM Ltd. 4
Case 2: Front impact accidents
PROTECTOR-superior design from KVM Ltd.
All pillars collapse forward – roof disintegrated - without safety concept
5
The roof will move
Front impact protectionOption 1: Diagonal column to stabilize the roof thru directing the impulse force into the lower body:• Column out of two strong tubes• Zig-zag interconnection in between bars• Correct angle from roof to column• Correct angle from column into body
Stabilizing column
Impulse force diverted into body
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Front impact protectionOption 2: Stabilize the roof thru reinforced pillars
PROTECTOR-superior design from KVM Ltd.
Stabilized side pillars
Fixed side glass
Sliding side glass
Roof
Disadvantage: reduces size of glasses
7
Case 3: Side impact accidents
PROTECTOR-superior design from KVM Ltd.
Whole body bent & side wall collapsed without safety concept
8
Side impact protection• Option 1: triangular vertical reinforcement inside legroom
Side reinforcement triangular
Side reinforcement triangular in legroom
No reinforcement at floor mounting
PROTECTOR-superior design from KVM Ltd.
Disadvantage: disturbing in the legroom
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Side impact protection• Option 2 (recommended): triangular vertical reinforcement underneath floor
Side reinforcement triangular underneath floor
PROTECTOR-superior design from KVM Ltd.
Gives structural strength against side impact and roll over
10
Side impact protection• Option 3 (recommended): triangular reinforcement longitudinal inside floor level
Side reinforcement triangular longitudinal
Side bent thru impact without reinforcement
View from above
Cross member
Cross member
Impact force
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Number of cross members• Enough for strength and safety according to load class (min. 4 for 26-seater, max. 8 for 71-seater)
• Not more than necessary – weight and cost relevant• Welding joints fist grade and verified
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Gangway and seat arrangement• Width of gangway recommended is 450 mm (Class IV, above 40 passengers)
and 350 mm (Class III, 26 – 40 passengers)
This requires for 3X2 seat arrangement a vehicle track width of 2250 mm or correctly curved side pillars
3 Seats = 1200 mm
Track width 2250 mm
2 Seats = 800 mm
Gangway 450 mm
150 mm maximum150 mm maximum
Side wall 50 mmSide wall 50 mm
PROTECTOR-superior design from KVM Ltd. 13
Side wall diagonal setting• Structural strength against rattling, cracks and bending• Prevent share force in an accident
PROTECTOR-superior design from KVM Ltd. 14
Wrong: cutting share force Correct: prevent share force
Passenger doorDimensions according to KEBS:• Minimum height 1650 mm• Minimum width 650 mm above 700 mm• 1st step height maximum 460 mm above ground
Function according to European Safety regulations:• In case of a panic after an accident the passengers want to press outward• The passenger door must swing outward otherwise it becomes a death trap
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Outward swing door
Outward sliding door or pantographic
Death trap inward swing door
Door hinges• Protruding hinges like at the drivers door must have a cover to protect against
sharp corners• Passers by on foot or passing vehicles will be cut by sharp corners
Option 1: Hinge cover Option 2: Hidden hinges
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Door grab handles• Safety for passing persons and traffic• Damage prevention
Groove mounting
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Original CKD
Dangerous protrusion
Uppermost stair• Uppermost stair not protruding into gangway
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Dangerous interference No interference
Door locking mechanism• Not protruding into door aperture
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Passenger seats safety• No sharp corners• No protrusions• Made out of round tubes• Width of seat frame 400 mm
per seat
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Seat mounting• Strength increased thru short lever and additional stiffness• Seat anchoring forward and sideward stronger
Long lever Short lever
Side mounting: additional strength
Floor mounting
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Passenger seats comfort• Dimensions• Seat rest height & inclination• Seat base height & inclination• Head rest cover
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Legroom
Front grille• Loose grille gets lost if not ALLWAYS locked and will endanger traffic • Front grille must be fixed to body thru hinges
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Front bumper• Prevention of damages thru road conditions• Creating sufficient air flow to radiator• Access to towing hook• Rounded curvature to support comfortable handling• No sharp corners to prevent accidents
PROTECTOR-superior design from KVM Ltd. 24
Original CKD bumperFormula: r(fr)+x(fr)
[mm/m]
Rear bumper• Prevention of damages thru road conditions• Access to towing hook• Rounded curvature to support comfortable handling• No sharp corners to prevent accidents
PROTECTOR-superior design from KVM Ltd. 25
Formula: r(re)+x(re)
[mm/m]
Rear overhang• To ensure comfortable vehicle handling (stability on the road) the rear overhang can
be maximum:60 % of wheel base measured behind rear axle to rear bumper
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60% of wheel base
wheel base
Rear glass / Emergency exit• Access & size according to legal regulations• Safe opening function• Cost saving shape• Recommended flat to save costs
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Unnecessary waste of material and money – very difficult to replace
Functional bus designPart 2: FUNCTIONAL features
20) Hump, 21) Windscreen, 22) Number plate provision, 23) Passenger door position 24) Side glasses
Hump
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Eddies at sharp corners increase air resistance
• Only small vehicles can be built like Formula 1 cars• Big vehicles require specific aerodynamic shape to reduce air resistance• Lower air resistance will reduce fuel consumption
Front hump eliminates eddies
Joint at roof bow
Windscreen• Cost reduction – recommended laminated, two piece flat glasses• Reduction of braking thru stones – high lower end• Reduction of heat – low upper end
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Number plate provision• To accommodate square & long type• Protection of number plate lamp – no protrusions
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Passenger door position• 1st step height 460 mm maximum – recommended behind front axle• Creating space for air duct :
– Air duct is disturbing in leg room– Shortest way for air intake required– Vibration buffing in between engine and body
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Driver door• Dimensions similar to CKD• Avoid additional weight and stress to the hinges
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Comfort in bus designPart 3: ERGONOMY = COMFORT features
25) Tool box, 26) Parcel rack, 27) Leg room 28) Arm rest, 29) Rearmost seat row
Rearmost seat row• Maximize leg room thru:
- Inclination of rear body backward- Seat rest of rearmost row to fit into shape of rear body
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Side view
View from above
Seat rest fit into body shape
Inclination of rear body backward
Lost space