Optimal Route

The Drawing - Optimal Route menu selection is enabled when the optional Business Tools extension has been installed and the focus is on a drawing window or on a drawing layer in a map window that contains lines and at least two points (between which a route can be selected). If you have not activated the Business Tools extension with a valid Business Tools serial number you will not be able to use the Optimal Route command.

The Optimal Route tool is a less-interactive version of the Optimal Route (Visual) tool. It simply finds the best route through a given set of locations (the selection or a saved selection), taking the locations in free order. To learn how to use this tool, see the Optimal Route (Visual) topic.

The drawing of road lines used must be a true road network that is a connected network. If there are small breaks between the road lines or if the ends of adjacent lines are not exactly coincident the drawing cannot be used as a road network.

The Optimal Route tool is provided for expert use as a specialized shortcut. In almost all cases for interactive work it is better to use the Optimal Route (Visual) dialog. However, the parameters used in Optimal Route are directly analogous to those used in the programming model when scripting optimal routes. The Optimal Route dialog is therefore especially useful to programmers who are learning to work with Manifold's optimal route capabilities via the scripting interface.

Controls

Locations	Points to use for locations. [All Objects] or [Selection] or a saved selection.
Roads	Objects to be used for road lines. [All Objects] or [Selection] or a saved selection.
Length	Choose a field to use that gives the length of each line in the road network. Choose the unit of measure used for the value in the field. Use the intrinsic field Length (I) if there is no explicit length field. On large road networks for which optimal routes may be repeatedly calculated, it is more efficient to create a "length" field in the table and to copy into that length column the contents of the Length (I) intrinsic field using the transform toolbar for tables. This will avoid a recalculation of Length (I) on the fly for each run and will improve performance. Lines with a zero or negative value for Length will be ignored and will not be used in the route.
Speed	Choose a field to use that gives the speed of travel for each line in the road network. Choose the units of measure used for the length and time values in the field, for example, miles per hour or kilometers per hour. By default, if a column named Speed is available in the drawing's table it will be automatically loaded into the Speed box.
Split roads at intersections	If checked, split road lines into separate lines at intersections with other roads.
Save report	Check to create a comments component in the project that contains a driving directions report.
Names	Field to use for road names in the driving directions report. If [None] is selected, the report will be created using a format without road names. By default, if a column named Name is available in the drawing's table it will be automatically loaded into the Name box.
Turns	Choose the writing style used to report turns. none results in no turns reported. The other two styles allow choice of turns using either compass directions (for example, to turn North or South at a given intersection) or relative directions (for example, to turn right or left at a given intersection).
OK	Find and optimal route and add a line object to the drawing representing the route. Add a comments component with driving directions if the Save report box has been checked. If no route has been as yet created using the Locate Route button, pressing OK is the same as Cancel.
Cancel	Exit the dialog without making any changes to the drawing.

Units of Measure used by Intrinsic Fields

The units of measure used by the Length (I) and Area (I) intrinsic fields depend upon both the projection of the drawing and the Tools - Options setting for the Use English measurement units option as follows:

· If the drawing is in Latitude / Longitude (that is, unprojected) Length (I) is reported in degrees and Area (I) is reported in square degrees.

· If the drawing is projected and the Use English measurement units option is turned off, Length (I) is reported in meters and Area (I) is reported in square meters.

· If the drawing is projected and the Use English measurement units option is turned on, Length (I) is reported in feet and Area (I) is reported in square feet.

Troubleshooting

Simple errors that may cause problems:

· Points to be used as locations are either not on lines or are not within the drawing's precision factor distance of a line. Since the default precision factor for a projected drawing is 0.000001 meter (about one thousandth of a millimeter) it is highly unlikely that points placed in drawings using anything other than Snap functions will be adequately close to a line to be considered "on" the line.

· The drawing of roads might not be a real network, that is, the ends of adjacent lines may not be coincident, there may be dangles or undershoots, breaks in the lines or other disconnects that prevent the lines shown from being used as a real network. Use Normalize Topology to "clean" the road network if need be, but keep in mind that poorly drawn road drawings might not be repairable even with the Normalize Topology tool.

· The units of measure used in the dialog do not correspond with the units of measure used in the drawing or used in the Speed or Length fields.

· The drawing is not projected and covers a sufficiently large area that errors arise. Always use a drawing that has been projected using a projection appropriate to the region of interest. For small regions (say, the size of a state or province in most countries), Orthographic is a fine meter-based projection that is a good bet.