21.1 Overview
This chapter discusses the different networks of highways within Texas that serve specific purposes and may require additional design considerations or higher standards. The following sections provide a general overview of each network as well as a historical summary. All of the networks discussed below can be seen on the
. The chapter includes the following sections and subsections:
21.1 Overview
21.2 Texas Highway Freight Network (THFN)
- 21.2.1 Vertical Clearance at Structures;
- 21.2.2 Signs, Overhead Sign Bridges (OSB’s), Signals;
- 21.2.3 Other Overhead Utilities; and
- 21.2.4 Bicycle and Pedestrian Accommodations.
21.3 Texas Trunk System (TRUNK)
21.4 National Highway System (NHS)
- 21.4.1 History of the National Highway System
21.5 Strategic Highway Network (STRANET)
21.6 Hurricane Evacuation Routes
- 21.6.1 Hurricane Evacuation Lanes; and
- 21.6.2 Contraflow Lanes.