Location, Materials, Types

Location

Traffic calming devices should be placed so they do not appear unexpectedly in the street scene. Ample distance for prediction and reaction should be ensured allowing car drivers to reduce speed sufficiently or, if necessary, to stop.

Marking

A speed reducer and its surroundings must be designed so that there is a clear visual difference from the rest of the stretch.

It should be ensured perceive and observe the carriageway marking and road signs in due time, and if necessary pre-warnings must be provided.

For use of signs and road markings see “Manual for Signs and Markings”.

Materials

In this addendum some recommendations for use of materials are given. For further recommendations see “Standard Specifications for Road and Bridge Works”.

Types of traffic Calming Measure

On Ghana Highway Authorities roads (or roads in Ghana (if this manual should be a national standard)) 7 different traffic calming devices are normally used.

  1. Road Humps
  2. Rumble Strips
  3. Jiggle Bars
  4. Centre Islands
  5. Ghost Islands
  6. Gates
  7. Pre-warnings

In the following chapters, each of the 9 main types is briefly described. The application of the main types is shown in table 1.

Type of traffic calming measure

Road Class / Type

Desired Speed
(km/h)

Annual Day Traffic
(vehicles / day)

Traffic Road

Local
Road

≥ 60

50

≤ 40

> 2.000

≤ 2.000

Motorway

Primary

Secondary

1   Road Humps

 

x

x

x

 

x

x

x

x

2   Rumble Strips

 

x

x

x

 

x

x

x

x

3   Jiggle Bars

 

x

x

x

x

x

x

x

x

4   Centre Islands

 

x

x

x

 

x

x

x

x

5   Ghost Islands

 

x

x

x

x

x

(x)

x

x

6   Gates

 

x

x

(x)

x

x

x

x

x

7   Pre-warnings

x

x

x

(x)

x

x

x

x

x



















Application of different traffic calming measures.

National roads

Inter regional and regional roads