bus design & safety according to specific kenyan requirements: legal background (the traffic act...

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


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


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


Front impact protectionOption 2: Stabilize the roof thru reinforced pillars


Stabilized side pillars

Fixed side glass

Sliding side glass

Roof

Disadvantage: reduces size of glasses

7

Case 3: Side impact accidents


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


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


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


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


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


Side wall diagonal setting• Structural strength against rattling, cracks and bending• Prevent share force in an accident


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


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


Door grab handles• Safety for passing persons and traffic• Damage prevention

Groove mounting


Original CKD

Dangerous protrusion

Uppermost stair• Uppermost stair not protruding into gangway


Dangerous interference No interference

Door locking mechanism• Not protruding into door aperture


Passenger seats safety• No sharp corners• No protrusions• Made out of round tubes• Width of seat frame 400 mm

per seat


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


Passenger seats comfort• Dimensions• Seat rest height & inclination• Seat base height & inclination• Head rest cover


Legroom

Front grille• Loose grille gets lost if not ALLWAYS locked and will endanger traffic • Front grille must be fixed to body thru hinges


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


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


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


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


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


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


Number plate provision• To accommodate square & long type• Protection of number plate lamp – no protrusions


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


Driver door• Dimensions similar to CKD• Avoid additional weight and stress to the hinges


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


Side view

View from above

Seat rest fit into body shape

Inclination of rear body backward

Lost space

bus design & safety according to specific kenyan requirements: legal background (the traffic act...

Documents

body protectorsuperior

swing door slide

bus design safety

share force slide

impact protection option

door hinges

passenger seats safety

safety concept