Using drivetime analysis to assess the availability of choice in maternity services

Andrew Oliver, National Audit Office

Spatial analysis – maternity services drivetimes

• Calculated distance and time people had to travel to closest maternity service by type

• Darker the shading, further travel time to access choice

• Small geographic units - LSOA

• Uses publicly available data

• Required additional products to core GIS software

• Calculated distance from LSOA to maternity service to provide full data set for report

Calculating maternity services drivetimes – data sources

Data sourced from the ONS website

Downloaded files at LSOA level showing for both years

•Geography shapefiles

•Population by gender and age

Data from the Department

List of maternity service locations and service type as at 2007 and 2013

Combined files to show females aged 16-44 for each of approx. 32.5k areas

Plotted LSOA population weighted centroids

Plotted postcode locations using GIS

Mapping techniques Software requirements

1. Plotting points• LSOA population weighted

centroids (from)• Location of maternity services (to)

Standard GIS software

2. ProcessingCalculation of from-to time (and distance) between LSOA and nearest maternity service

Drivetime add-in

3. Creating output Mapping the results Standard GIS software

Calculating maternity services drivetimes – software

Uses standard GIS software – MapInfo Professional

Supplemented with drivetime add-in and road network

Calculating maternity services drivetimes – processing

• Drivetime software uses digital road network to plot route

• Nominal scale of 1:50,000

• Route time and distance calculated using pre-defined fixed speeds

• Some adjustment for road type and conditions

• Sufficient precision for indicative analysis

• Load from and to sites

• Repeat to account for different maternity service types

• Repeat for both 2007 and 2013

• To provide a full data set for report, calculated metrics from LSOA to maternity service rather than creating buffers from maternity service

Maternity services drivetime results

• Darker the shading, further travel time to access choice, in 2013:

• 79% of females aged 16-44 have both an obstetrics unit and a midwife led unit within a 30 minute drive

• 3% of females aged 16-44 have neither maternity service type within a 30 minute drive

• Access to choice has improved since 2007, with additional midwife led units opened

2007

2013