Sleeping Policeman (Road humps / Speed bumps)

Sleeping Policeman (Road humps / Speed bumps)

The most effective measures to lower vehicle speed is by using sleeping policeman or known as road hump. The road humps are designed to have different sizes and shape to suit the requirements and place of services. Some are narrow as to deliver a sharp jolt to vehicle suspension and to gives discomfort when crossing at high speed. The wide humps are mainly for further reducing the vehicle speed due to longer crossing time. The road hump is normally extended from curb to curb across the full road with a drainage gap.

They are made of a hard, high impact rubber that lasts longer than plastic, asphalt or concrete speed bumps. They are moveable can be easily relocated. Road hump is grooved to provide traction in rain or snow and easy drainage of water. Built-in cats’ eyes provide necessary night visibility, alerting drivers to slow down.

The road hump is made from NR and SR and its blend. The black slab is made from black rubber compound base on 100% NR. The rubber is formulated with suitable hardness to with stand heavy load, forces and compression. The tear and tensile strength is immaculately high so that it resistant to tearing and chunking. The vulcanisate is also designed to be weather resistance by adding antiozonant and antioxidant.

For yellow compound similar properties were assured but with extra protection on weathering. Since coloured compound more prone to weathering it is formulated base on blending with weather resistant rubber. The colour pigment used is also of higher grade with weather fastness above approximately 5. Extra protection agents were added into the formulation such as UV absorber and light stabilizer. With these extra protections the yellow slab or portion of the hump should be more resistance to fading and weathering.

The road hump is also designed to have built in reflector. The reflector used is of high intensity grade which is bright, durable, retroreflective material designed to have similar appearance when viewed in the daylight or by retroreflected light at night. The reflective sheeting consists of optical lens elements adhered to a synthetic resin and encapsulated by a flexible, transparent plastic with a smooth outer surface. The reflector sheeting featured a pressure-sensitive adhesive for ease of application. The main properties of it performance are 3 times brighter than Engineer Grade reflective sheeting and retain good reflective to ensure safety condition.

Manufacturing Process

• Mixing of compound
  
  There are two compounds used in the manufacturing of road hump, one black and one yellow. The compounds are mixed separately either using internal mixer or two-roll mill. If internal mixer is to be used, master batch is mixed in the internal mixer first under controlled temperature. The master batch is then added with curatives using two-roll mill. If the mixing is to be carried out on two-roll mill, the mixing is to begin with mastication of the rubber and followed by addition of ingredients such as activators, filler and oil. The curatives are to be added last.
  
  
  
• Curing of components
  
  There are three separate components for making road hump, they are black and yellow intermediate slabs and the end slab. The intermediate slabs using the same mould for black and yellow. However the mould must be cleaned before changing to new compound.
  
  The curing can be carried out using the same press for each individual component. The economical moulding temperature is 170°C. The cure time is approximately 30 minutes for intermediate slab and approximately 20 minutes for end slab. The moulds are designed to facilitate easy fixing to the platens.
  
  
  
• Trimming process
  
  
• Bolting to road surfaces