Efficiency Change
The efficiency change index provides an overview of the geographical distribution of accessibility impacts that result from changes or policy interventions to network configuration, service levels and/or the land use structure. It is used in accessibility comparisons over a time line.
Efficiency improvements (positive figures) are associated with travel time reductions (through speeding up of services or the introduction of more direct routes), higher service frequencies and/or land use intensification. Efficiency reductions (negative figures) are associated with a deterioration of travel times, lower service frequencies and/or a decline of population or jobs in the catchment.
where:
ΔEi = Change in efficiency centrality of node i
acti,b = number of residents and jobs in defined local catchment of node i before the intervention
acti,a = number of residents and jobs in defined local catchment of node i after the intervention
actj,b = number of residents and jobs in defined local catchment of node j before the intervention
actj,a = number of residents and jobs in defined local catchment of node j after the intervention
Lij,b = cumulative impediment between nodes i and j before the intervention
Lij,a = cumulative impediment between nodes i and j after the intervention
N = all activity nodes on the network
Efficiency improvements (positive figures) are associated with travel time reductions (through speeding up of services or the introduction of more direct routes), higher service frequencies and/or land use intensification. Efficiency reductions (negative figures) are associated with a deterioration of travel times, lower service frequencies and/or a decline of population or jobs in the catchment.
where:
ΔEi = Change in efficiency centrality of node i
acti,b = number of residents and jobs in defined local catchment of node i before the intervention
acti,a = number of residents and jobs in defined local catchment of node i after the intervention
actj,b = number of residents and jobs in defined local catchment of node j before the intervention
actj,a = number of residents and jobs in defined local catchment of node j after the intervention
Lij,b = cumulative impediment between nodes i and j before the intervention
Lij,a = cumulative impediment between nodes i and j after the intervention
N = all activity nodes on the network
