This book presents a study of the use of GPS
equipped probe vehicle to collect traffic data on a
motorway network. Two types of GPS equipped probe
vehicles, active and passive, have been studied. A
passive probe vehicle was considered to provide only
link journey time and a minimum number of probe
vehicles is required for reliable estimation. This
research has studied the distribution of individual
journey times and calculated the sample size of
probe vehicles required in different traffic
conditions. The sample size has shown to be
generally stable for the same link, but may decrease
in heavier traffic. An active probe vehicle was
found to be able to determine vehicle position and
speed at 1 Hz frequency over an entire journey. By
analysing the speed profile of probe vehicles,
journey times can be estimated from fewer probe
vehicles than normally required.
equipped probe vehicle to collect traffic data on a
motorway network. Two types of GPS equipped probe
vehicles, active and passive, have been studied. A
passive probe vehicle was considered to provide only
link journey time and a minimum number of probe
vehicles is required for reliable estimation. This
research has studied the distribution of individual
journey times and calculated the sample size of
probe vehicles required in different traffic
conditions. The sample size has shown to be
generally stable for the same link, but may decrease
in heavier traffic. An active probe vehicle was
found to be able to determine vehicle position and
speed at 1 Hz frequency over an entire journey. By
analysing the speed profile of probe vehicles,
journey times can be estimated from fewer probe
vehicles than normally required.