2.2.1 Geometric Data

Geometric data is related to the physical characteristics of the roadway facility. Below is a list of general geometric data that may be needed to perform traffic analyses. Additional data may be needed depending on the characteristics of the project study area; this is not an exhaustive list.
  • Geographic coordinates (e.g., NAD 83);
  • Number of lanes;
  • Lane assignment;
  • Lane, shoulder, and crosswalk widths;
  • Presence of sidewalks and pedestrian elements;
  • Type of lane (e.g., general purpose, managed lanes, bus-only lane, bike lane);
  • Length of turn lanes or bays;
  • Ramp spacing;
  • Clear zone;
  • Curvature of roadway (i.e., centerline alignment);
  • Grade;
  • Median width;
  • Median type (e.g., divided, undivided, barrier);
  • ROW;
  • Driveway entries and location; and
  • Location of railroad crossings
Geometric data can be gathered using TxDOT’s Open Data Portal, online aerial imagery (e.g., Google Earth, Google Maps, Bing Maps, Nearmap), survey files, as-builts (i.e., plans that reflect the project as actually constructed), and other online resources. However, it is recommended that a field visit be performed, when possible, to verify the existing geometric conditions data gathered digitally. A field visit is necessary to verify geometric information in areas with limited or dated aerial imagery, or when as-builts are not available.