Table 1

Description of various data and their sources used as input into the development travel time to the public health facilities in northern Namibia.

Map Layer

Description

Classification

Speed (km/h)

Model


Land use/land cover

Spatial representation of all different land use and land cover types. Two land cover grids were processed (1) basic land cover grid (2) combined grid that incorporates roads and rivers with same resolution as the DEM

Tree cover, broad leaved deciduous or evergreen

5

WALKING

Tree cover, needle leaved, deciduous or evergreen

5

WALKING

Tree cover, other

2

WALKING

Shrub cover

5

WALKING

Herbaceous cover

3

WALKING

Sparse herbaceous

4

WALKING

Cultivated and managed areas

5

WALKING

Bare areas/desert

2

WALKING

Water Bodies

0

NONE


Roads

Classified into three broad categories; Primary roads (class A), Secondary roads (class B); Tertiary roads (class C). Each road class was assigned a slightly different speed.

Primary roads

80

NONE

Secondary roads

60

NONE

Tertiary roads

10

CYCLING


Rivers

GIS layer representing barrier to movement. Only major rivers were used to reduce the complexity of running the algorithms

NA1

0

NA1


Digital elevation model

Altitude values that are used in anisotropic calculation; Original DEM 30 m ASTER grid; resampled to 100 m pixel size

Degree of Slope (< 0.5°)

4.88

WALKING

Degree of Slope (5.0°)

3.71

WALKING

Degree of Slope (10.0°)

2.71

WALKING

Degree of Slope (20.0°)

1.41

WALKING

Degree of Slope (30.0°)

0.66

WALKING


The assumed travel speeds for each input feature are also shown

1. NA is an abbreviation for ' Not Applicable'

Alegana et al. International Journal of Health Geographics 2012 11:6   doi:10.1186/1476-072X-11-6

Open Data