HierarchyLevelSet

Procedure HierarchyLevelSet(h2, h3, h4, h5: double);

Sets the 4 hierarchy parameters for use in hierarchical routing. Values should be expressed in km or miles, depending upon the configuration file.

These values are normally set through the INI file, but can be overridden if required.

Input requirement: h2 >= h3 >= h4 >= h5 >= 0.

By default all parameters are set to infinite, meaning no hierarchy is applied.

We have executed tests with TomTom (netbclass field) and Navteq (func_class field) databases and recommend these values:

Tests were executed on UK data with a large number of random routes. Compared to not using a hierarchy, calculations were 6 times faster with TomTom data (0.3 secs per route) and 11 times faster with Navteq data (0.1 sec per route). Navteq has better hierarchy attributes and a little less details in the network, hence the differences.

For short routes (<50 km) there is only little difference between using a hierarchy or not, while calculation of longer routes (>400 km) in the UK may be as much as 20-40 times faster (Navteq) and 6-30 times faster (TomTom).

See also Hierarchical routing

ActiveX / VCL / CLX component: RWcalc