The Texas Department of Transportation (DOT) enforces all road maintenance and construction in the state, which has five classifications of roads – Urban Streets, Suburban Roadways, Two-Lane Rural Highways, Multi-Lane Rural Highways and Freeways. The state drafts specific guidelines regarding road proportions and configurations, including the width of the lanes and medians. These widths depend on the location of the road and how much average traffic it gets during the course of a day.
Roadway Width of Urban Streets
Urban Streets refer to roadways in Texas municipalities that provide access to the property surrounding them. Driveways, medians and intersections offer access to these roads. The following factors influence the right-of-way for urban streets:
- Traffic volume.
- Land use.
- Cost and availability.
- Expansion extent.
Width for streets in urban areas includes cross-sectional elements, like vehicular travel and turning lanes, bicycle lanes, shoulders, parking lanes, medians, borders, sidewalks and sidewalk offsets, slopes, ramps and connecting roadways with interchanges. Arterial lanes on urban streets should be a minimum of 11 feet, and collector lanes require a 10-foot minimum width unless they are in industrial areas, which have a 12-foot minimum requirement.
Local urban streets should be at lease 10 feet wide, but in some residential areas, they might be 9 feet wide. A median width of 16 feet with a 4-foot divider is desirable to accommodate one left-turn lane, while an 18-foot width is the requirement for pedestrian refuge.
Lane Width of Suburban Roadways
A suburban roadway is a high-speed roadway that allows for transition between urban streets (low-speed roads) and rural highways (higher speed roads). Suburban roadways are typically one to three miles long and have from 10 to 30 driveways per mile. They have characteristics that are both rural and urban in nature. For example, suburban roadways have sections that allow drivers to maintain higher speeds but also have curbs and gutters for drainage.
Suburban roadways in Texas should have arterial lanes of at least 11 feet wide, but they can be a minimum of 10 feet in some areas. Collector lanes have a minimum width of 10 feet, but industrial areas have a higher minimum of 12 feet. A 16-foot width for two-way left-turn lanes is desirable, but they must be at least 14 feet wide.
Width of Two-Lane Rural Highways
Two-lane rural highways have these roadway design elements:
- Access Control: Frontage or parallel service roads should not run along two-lane rural highways, as they give the impression that the two-way road is a one-way road. Driveways in high fill or deep-cut areas should be parallel to these roadways for a short distance to allow drivers to merge onto them safely.
- Transitions to divided highways with four lanes.
- Passing Sight Distances: This describes the highway length required by a driver to pass another vehicle without cutting it off and before meeting an oncoming motor vehicle.
- Speed Change Lanes: These include climbing, left-turn and right-turn lanes.
A two-lane rural highway's minimum width for an arterial lane is 12 feet. Collector lanes have a 10-foot minimum width if there are less than 400 drivers traveling that highway daily. This minimum goes up to 11 feet if up to 2,000 people travel the highway daily, and 12 feet if more than 2,000 people use it every day.
Travel lanes have the same minimum width as collector lanes. The DOT requires right-turn deceleration lanes to be at least 10 feet wide.
Width of Multi-Lane Texas Highways
Multi-lane rural highways in Texas must have these elements:
- Access Control: Access control should be in interchange areas or run continuously through a section of the highway, depending on traffic volumes, roadside development, economic conditions and right-of-way ability, among other factors.
- Medians: Should provide enough storage space for tractor-trailers, reduce glare from headlights, reduce the chances of head-on collisions and have a pleasing appearance.
- Turn Lanes: Their location should be wherever vehicles must slow to leave an area or accelerate to merge onto the highway.
- Shoulders and Travel Lanes.
- Transitions to four-lane divided highways.
- Interchanges and grade separations should be at highway or railroad crossings to increase safety in areas that are crash-prone.
Multi-lane rural highways in Texas must be at least 12 feet wide. No median should be wider than 60 feet at intersections in suburban areas, except to accommodate larger vehicles when turning and crossing, at which point their desired width should be 76 feet to give enough space for tractor-trailers to maneuver.
Width of Freeways or Interstate Highways in Texas
A freeway is a controlled access facility with divided multi-lanes. They are arterial roadways, but their design characteristics set them apart from other arterials that are not controlled. The width of the lanes on a Texas freeway should be a minimum of 12 feet. The number of lanes depends on the amount of traffic in that area.
Medians are 76 feet wide in depressed freeway sections, with a reduction to a minimum of 48 feet where special conditions, like topography and right-of-way, apply. A width of 24 to 30 feet applies to freeway sections that have flush medians. On those with six travel lanes or more and a 24-foot flush median, there should be 10 feet for inside shoulders and a two-foot offset to the barrier center line.
Due to high speed and volume traffic on urban freeways where future lanes will be added, the median width of 24 feet can increase by multiples of 12 feet when necessary.
Michelle Nati is an associate editor and writer who has reported on legal, criminal and government news for PasadenaNow.com and Complex Media. She holds a B.A. in Communications and English from Niagara University.