A median (i.e., the area between opposing travel lane edges) is provided primarily on divided highways to separate opposing traffic streams. The general range of median width is from 4- to 76-ft. The design width is dependent on the context classification and traffic characteristics of the highway or street facility. When determining the minimum median width, consideration should be given to the demand for U-turn movements based on local access requirements. See for minimum median width required to accommodate various design vehicles.

The primary functions of medians are to provide the following:

The types of medians that are commonly used include:

Depressed medians are generally found in the rural context and will range from 48- to 76-ft in width. This type of median shares a common ditch between each side of the divided facility and offers an area for storm runoff to collect. This type of median can also provide storage space for snow during snow removal operations.

For multi-lane rural highways without access control, a median width of 76-ft is preferable to provide complete shelter for trucks at median openings. These wide, depressed medians are also effective in reducing headlight glare and providing a clear zone for run-off-the-road vehicle encroachments. They also provide a pleasing appearance and reduce chances of head on collisions. Wide medians should generally be used whenever feasible but median widths greater than 60-ft have been found to be undesirable for intersections that are signalized or may be signalized in the design life of the project. The increased time for vehicles to cross the median can lead to inefficient signal operation.

Where economically feasible, freeways in rural areas should also desirably include a 76-ft depressed median. However, since freeways by design do not allow at-grade crossings, median widths do not need to be sufficient to shelter crossing trucks. In this regard, where ROW costs are prohibitive, reduced median widths (less than 76-ft) may be used. Statistical studies have shown that over 90 percent of median encroachments involve lateral distances traveled of 48-ft or less. To account for this, unless continuous longitudinal barriers are used, depressed medians on rural freeway sections should be 48-ft or more in width.

A raised median is used where it is desirable to control or restrict mid-block left turns and crossing maneuvers. Installing a raised median can result in the following benefits:

This type of median can typically be found on roadways in the suburban, urban, or urban core contexts and may range from 4 to 36-ft in width.

On high-speed facilities, mountable curb should be used for the raised median.

A raised median design should be considered where:

For these conditions, a raised median may improve safety by separating traffic flows and controlling left-turn and crossing maneuvers. The use of raised medians should be discouraged where the roadway cross-section is too narrow for U-turns.

For median left turn lanes at intersections, a width of 16-ft will effectively accommodate left-turning traffic and a 4-ft median divider measured from the face of curb. However, where pedestrian refuge is a consideration for raised medians, allowances for a 6-ft width raised median, measured from the back of curb, is preferred, (6-ft measured from the face of curb is the minimum requirement). See for additional guidance.

An illustration of this difference is shown in .

To prevent recurring damage to the raised median divider, the divider should be at least 2- ft wide (measured from face of curb to face of curb). If pedestrians are expected to cross the divider, then the divider should be a minimum of 5-ft wide (normal to direction of pedestrian travel) to accommodate a cut-through landing or refuge area that is at least 5-ft x 6-ft.

Flush medians are medians that can be traversed. A flush median cannot prevent left-turn and cross maneuvers since it can be easily crossed and cannot physically prevent these types of movement. Therefore, for roadways where access control is desirable, flush medians should not be used. When flush median designs are selected, it should be expected that some crossing and turning movements can occur in and around these medians. Full pavement structure designs will usually be carried across flush medians to allow for traffic movements.

A flush median design should include the following:

This type of flush median is generally located on roadways in the rural or suburban contexts with roadside development and may range from 4- to 16-ft in width. 4-ft wide flush medians provide little separation of opposing traffic and minimal refuge area for pedestrians. 14- to 16-ft wide flush medians offer space for traffic turning left but does not offer protection for crossing vehicles.

Urban and suburban freeways generally include narrower, flush medians with continuous longitudinal barriers. The median width may vary from 24- to 30-ft, with 24-ft commonly used. See for recommendations on the use of median barriers. See for additional information on freeway medians.

TWLTL are flush medians that may be used for left turns by traffic from either direction on the roadway. The TWLTL is appropriate where there are operational concerns for a high frequency of mid-block turns exist or are anticipated, such as areas with (or expected to experience) moderate or intense strip development. Used appropriately, the TWLTL design can improve the safety and operational characteristics of streets as demonstrated through reduced travel times and crash rates. Recommended median lane widths for the TWLTL design are as shown in . When applying this criterion to new location projects or on reconstruction projects the corresponding preferable width should be used where widening necessitates the removal of exterior curbs. Minimum values shown in are appropriate for restrictive ROW projects and improvement projects where attaining the desirable width would necessitate removal and replacement of exterior curbing to gain a small amount of roadway width.

A site can be considered suitable for the use of a TWLTL when the facility meets the following criteria:

All cross sections should be evaluated for pedestrian crossing capabilities. See for additional guidance.

For rural town, suburban, urban, and urban core contexts, median openings should only be provided for street intersections or at intervals for major developed areas. Spacing between median openings must be adequate to allow for introduction of left-turn lanes and to prevent false calls at signal detection loops.

As the number of median openings increase, the interference between through traffic and turning traffic increases. To reduce the conflicts between turning traffic and through traffic, turn bays should be provided at all median openings. Recommended minimum median opening spacings are based on the length of turn bay required.

Directional openings, pictured in , can be used to limit the number and type of conflicts.

The positive offset design shown in can improve the sight distance for left-turning vehicles where there are opposing left-turn lanes. This design has also been found to substantially reduce the frequency of left-turn crashes compared to negative (a) or no offset (b) designs and is desirable for use where practical. Further discussion and examples of offset left-turn lanes can be found in .

An important factor in designing median openings is the shape of the median end or median nose. The median end shape can directly alter the effective turning path the design vehicle can make.

The shape of a median nose should be designed to accommodate the turning path of the design vehicle.

One form of a median end at an opening is a semicircle, which is a simple design that is satisfactory for median widths less than 10-ft wide. One alternate median end design that fits the paths of design vehicles is a bullet nose. The bullet nose is formed by two symmetrical arcs with a small radius to round the nose.

See for an illustration of these two types of median ends.

Consider the use of local design standards for median noses where available. In the absence of a local standard refer to Chapter 9 of for more information regarding the design of median openings.

On rural divided highways, closely spaced median openings can cause interference between high-speed through-traffic and turning vehicles. The frequency of median openings varies with topographic restrictions and local requirements. As a general rule,

the minimum spacing should be one-quarter mile or greater in rural areas.

It is typical to provide median openings at all public roads and at major traffic generators such as industrial sites or shopping centers. Additional openings should be provided to maintain a maximum one-half mile spacing.

As shown in , rural divided highways should provide left-turn lanes at all median openings and right-turn deceleration and acceleration lanes should be considered at intersections with highways or other major public roads with significant turning movements. See TxDOT’s “Auxiliary Lanes” section and related table for additional considerations and warranting thresholds for right-turn deceleration and acceleration lanes as well as left-turn deceleration lanes at median openings.

For divided highways with independent mainlane alignment, particular care should be exercised at median openings to provide a satisfactory profile along the crossover with flat approaches to the mainlanes.

For divided highways with independent mainlane alignment, particular care should be exercised at median openings to provide a satisfactory profile along the crossover with flat approaches to the mainlanes.

Median openings should be at least 40-ft wide, or the width of the crossroad pavement plus 8-ft.

Design vehicles are often used as the basis for minimum design of median openings, particularly for multilane crossroads and skewed intersections.

See for additional information.

Median encroachment countermeasures should be considered where appropriate. High severity injuries and fatalities are a result of cross median crashes on high-speed roadways. Reducing median encroachment reduces cross median crashes and fixed object crashes in the median. The following guidelines below are for reducing the frequency and severity of median related crashes on divided highways: