Creating Traffic Condition Maps

After configuring the base map, create unique value thematic maps based on road condition fields in road data. Use green, yellow, and red to represent smooth, slow-moving, and congested traffic respectively. Set visible scales for layers to display bidirectional road conditions at small scales and all road conditions at large scales. Traffic condition maps for different time periods can also be created as follows:

Large-Scale Traffic Condition Maps

Add navinfo line data to the configured base map window. Create unique value thematic maps for 6:00, 9:00, and 18:00 using Condition6, Condition9, and Condition18 fields respectively. Field value 1 represents smooth traffic, 2 for slow-moving, and 3 for congested. For example, in a "Condition" field: value 1 (green lines) = smooth, value 2 (yellow lines) = slow, value 3 (red lines) = congested, as shown:

Set the thematic layer's minimum visible scale to 1:9028. To view conditions at specific times, hide other time period layers.

Small-Scale Traffic Condition Maps

Traffic conditions should be mapped hierarchically according to map scales. For example:

  • Ramp conditions visible at large scales may disappear at medium scales
  • Service road conditions visible at large scales may hide at small scales

For small-scale road data, ensure two field types exist:

  1. Fields indicating single/double lines and visibility
  2. Fields showing congestion levels
Create unique value thematic maps using congestion fields, then configure:
  • Field expressions for line type/visibility
  • Offset distance (0.1mm units) for dual-line roads
Implementation steps:

  1. Double-click the thematic layer in Layer Manager. In the Thematic Map panel's Advanced section:
    • Check "Traffic Situation"
    • Set "Road Grading" field:
      • 0 = hidden (e.g., service roads at small scales)
      • 1 = single-line roads (e.g., ramps)
      • 2 = dual-line roads (e.g., highways)

    Note: Offset effects only work with non-system symbols (ID beyond System0-5). Modify line symbols needing offset via Unique Value Thematic Map Properties Panel.

  2. In "Road Offset", set displacement for dual-line roads:
    • Positive values: left offset
    • Negative values: right offset
    This maintains clear dual-line condition display at small scales.

    3. At reduced map scales, overlapping roads may obscure bidirectional conditions. SuperMap's Traffic Line Correction resolves this by processing:

    • Condition visibility
    • Offset values
    See Traffic Line Correction for implementation.