Managed lanes are defined by the FHWA as highway facilities or a set of lanes where operational strategies are proactively implemented and managed in response to changing conditions. This increases freeway efficiency, maximizes capacity, manages freeway demand, and generates revenue. Examples of managed lanes include high occupancy vehicle (HOV) lanes, value-priced lanes, high occupancy toll (HOT) lanes, and exclusive or special use lanes such as express lanes, bus lanes, transit lanes, and reversible flow lanes.

The following geometric design elements and related topics should be considered in the design of a managed lane facility:

Refer to or for additional information on managed lane facilities.

The geometric design of managed lane and general-purpose facilities (i.e., freeway mainlanes) should be based on design principles and criteria for freeways. This reinforces driver expectations and promotes system connectivity.

Managed lanes are typically constructed as dedicated lanes within a freeway facility or in some cases, a freeway within a freeway. See for an example typical section.

Managed lane design should match the design elements and traffic control devices on the adjacent freeway facility so that there is an established driver expectancy between both facilities. For example, if the adjacent freeway provides 50-mph ramps, a similar design should be applied to the ramps that connect the managed lanes and general-purpose lanes.

The design speed of a managed lane facility, including ramps and direct connectors, should match the design speed of the adjoining freeway facility.

This is especially true if there is a possibility of the managed lane facility being used by general-purpose traffic during the off-peak hours or at some time in the future. If there is no possibility that the facility will be used by general purpose traffic, and if use of this facility will be limited to a single vehicle type, such as buses, then the specific physical dimensions and operating characteristics of that vehicle should be considered in the design.

Managed lane facilities must match the context classification of the adjoining freeway facility

Planning studies should be performed in conformance with a analysis to confirm the number of through lanes needed for the managed lane system. This is particularly important when considering system-level demand inputs and outputs for a regional network of managed lanes.

The recommended and minimum lane width for a managed lane facility is 12-ft.

For desirable and minimum shoulder widths refer to Chapter 3.

Medians on managed lane facilities should be designed in the same manner as freeway medians. For guidance on freeway Medians, see .

For guidance on Horizontal Alignment, see .

For guidance on Vertical Alignment design, see . Maximum grades for managed lane facilities must follow the requirements of freeways.

For guidance on Cross Slope and Superelevation, see and .

For Clear Zone requirements for managed lane facilities, see for freeways.

For guidance on Vertical Clearance, see .

There are multiple ways to provide separation between managed lanes and the general-purpose lanes of a freeway. Barriers, buffers, flexible delineators, pavement markings, and separate facilities can all be used. In some cases, facilities may have a combination of separation types (e.g., a mixture of buffer separation and pavement marking separation where cross section is limited).

For additional information on separation methods for managed lane facilities, refer to .

Access to and from the managed lane facility must follow the ramp design guidance, see .

In situations where weaving is required on the managed lane facility, the minimum ramp spacing must be determined with the analysis procedures outlined in the . For early planning purposes, the applicable weaving distances on a freeway between two system interchanges, a system interchange and service interchange, or two service interchanges should be used.

Access to managed lane facilities can either be accomplished through a continuous access or limited access approach. The selection of access type is based on a general evaluation of the performance and management benefits for the entire freeway system as well as the costs of constructing and operating the managed lanes.

Drainage criteria for managed lanes is identical to the drainage criteria of freeways. Refer to TxDOT’s for drainage criteria requirements for freeways.

For managed lanes located to the left of general-purpose lanes, drainage is a particular consideration when the lanes are separated by a median barrier. In these scenarios, the shoulder width and inlet spacing must be designed to handle the required ponded width.