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GENERIC STEP-BY-STEP APPROACH STEP THREE

Figure 21 provides an example of network links that have been removed where barriers exist.

Figure 21: Network links have been removed where geographic barriers exist

F Assign speed limits to the movement network (if required)

Only follow this step if travel time is used instead of travel distance as an access measure in your study.

Determine the speed that people travel along different types of roads using different modes of transport
(by foot, by bus or by car/taxi). These must then be added to the road network. Table 3 provides an
example of the speeds that can be used for different road types and network links considering the
different modes of transport.

Walking speeds can be standardised at 4.5km/hour for all the different types of roads and network
links. Considering the normal speed limits associated with the different types of roads, the speeds can
be reduced by a factor of between 10% - 20% for car/taxi speeds and 30% - 40% for bus speeds. This
is to take into consideration variations in speed because of changes in the road gradient, road curvature
and to cater for possible stops along the way.

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