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.