Paper 2 · traffic flow survey methodology
A researcher wants to show, on a single sketch map, the total volume and direction of rush-hour traffic flowing along several roads into a city centre. Which mapping technique should be used?
AChoropleth map, using shaded colour bands to show traffic density across each road corridor
BDot map, using one dot to represent each individual vehicle counted along the roads
CFlow-line map, using arrows whose width shows volume and whose direction shows the flow
DIsoline map, drawn by connecting points of equal recorded traffic speed on the roads
Explanation: The total volume and direction of a flow (such as rush-hour traffic) is conventionally shown using a flow-line map, where each arrow follows the route travelled and its width is drawn proportional to the volume carried, while its direction shows which way the traffic moves. Choropleth maps show area-based density categories, dot maps show discrete point locations, and isoline maps connect points of equal value such as speed, none of which convey a directional volume along a route.
Derived from ZIMSEC Geography Paper 2, November 2004, Q1
