shows target design values for Arterials for each context classification. These design values may be adjusted based on the anticipated target speed and a performance-based practical design evaluation of the corridor (see ).

The subsections following provide additional discussion for each design element and factors influencing these values.

The design speed for arterials can vary greatly between the five contexts.

The design speed should reflect the anticipated target speed during non-peak hours.

However, the design speed should not exceed the limits of prudent construction, right-of-way, and socioeconomic costs. Minimum design speeds for arterials are shown in .

See for additional guidance on selecting the appropriate design speed.

Design speeds for rural arterials must be equal to 60 mph or higher in rolling terrain and 70 mph or higher in level terrain. See for guidance on the different types of terrain.

Rural town arterial design speeds are similar to the urban context in that they may vary from 30 to 45 mph.

Design speeds for arterials in the suburban context range from 40 to 60 mph and will typically act as a transition segment between rural and urban or rural town sections of roadway.

Urban core arterials generally have design speeds of 35 mph or less while urban arterials typically have design speeds ranging from 30 to 45 mph.

Arterial roadways for all contexts should be designed to accommodate traffic projections for a 20-year period into the future. However, some elements may be based on shorter or longer design periods (e.g., a 20-year period for flexible pavements and a 30-year period for rigid pavements). For additional guidance on selecting the appropriate periods for forecasting design traffic volumes, see or refer to .

Projected volumes for other modes of transportation, such as pedestrians and or bicyclists, must also be estimated in the design of the facility.

While future estimates of transit and non-motorized modes may not be available, the designer may use available planning and land use documents to assist in determining future levels of nonmotorized demand.

Arterials and their auxiliary facilities in the rural context should be designed for Level of Service B or better in the design year as defined in the . All other contexts should be designed to Level of Service C or better. Level of Service D may be allowable for heavily developed or constrained areas.

See for more information regarding level of service as it relates to facility design.

Arterials in dense developed urban areas may necessitate the use of Level of Service C or D in the design year.

The describes methodology and applications for level-of-service criteria and capacity for automobiles, as well as pedestrians, bicycles, and transit, for urban street facilities. Urban street facilities as defined as having a length of:

It also provides similar guidance for urban street segments, which are shorter than urban street facilities and allow analysis of more specific locations as needed. The theoretical automobile capacity of a through lane on an urban street facility or segment is 1,800 vph; adjustment factors reduce this capacity to account for the effects of certain roadway characteristics. Refer to the methodology should be used to determine the recommended number of through lanes needed for given conditions on a specific facility or segment.

Where arterials in rural areas pass through a rural town context and non-motorized roadway users are present, or likely to be present in the future, the motor-vehicle level of service may be reduced to provide a more balanced level of service for all modes of transportation.

Travel lane widths may vary from 10 to 12-ft depending on the context classification of the facility and anticipated target speed.

The number of lanes required to accommodate the anticipated traffic in the design year is determined by the level of service evaluation as discussed in the .

The typical range of lanes for arterials is two to four travel lanes in each direction.

Due to the high speeds associated with rural arterials,

lane widths must be designed to 12-ft.

Rural town arterials should provide 12-ft lanes due to the agricultural vehicles and trucks that will drive on these types of facilities. 11-ft lanes may be used in restrictive Right of Way (ROW) conditions.

Lane widths may be reduced to 10-ft in highly constrained areas where both of the following conditions are present:

Engineering judgement must be exercised when determining if a 10-ft lane width is acceptable.

Use of 10-ft travel lanes must be approved by the District and approval documented in the project file.

Suburban, urban, and urban core arterials will commonly use 11-ft lanes on facilities with lower target speeds as a traffic calming measure (i.e., 45 mph or less). If the anticipated target speed is 50 mph or greater and/or truck volumes are significant (>10%), 12-ft lanes should be used.

Lane widths may be reduced to 10-ft if the conditions described in are met.

Arterial shoulder widths may vary from 4 to 10-ft depending on the context classification of the facility and anticipated target speed.

See for additional information on shoulders and shoulder surfacing requirements.

Outside shoulder widths on rural arterials should normally be 10-ft since they will typically have high operating speeds (60 mph or greater). In highly constrained situations, outside shoulder widths may be reduced to 8-ft.

Rural arterials on the Texas Highway Freight Network (THFN) should provide 10-ft minimum outside shoulders.

For two-lane rural arterials, shoulder widths may be reduced to 4-ft if future ADT volumes are less than 400 VPD.

A minimum of 4-ft shoulders must be used at locations adjacent to roadside barrier.

A minimum inside shoulder width of 4-ft must be provided for 4-lane divided rural arterials. On 6-lane or more divided arterials, 10-ft inside shoulders should be provided. The inside shoulder width may be reduced to 4-ft in constrained situations.

Suburban arterial shoulder widths can vary from 4 to 10-ft. It is preferred to have 8 to 10-ft shoulder widths on suburban roadways with high operating speeds (50 mph or greater).

Due to the higher speeds frequently associated with this context, shoulders are usually provided instead of curbs. See for additional information on curbs.

Rural town, urban, and urban core contexts will typically use curbs and maintain curb offsets instead of shoulders due to the lower operating speeds. See for curb offset requirements and additional information on curbs.

For uncurbed roadways, shoulder widths may vary from 4 to 10-ft.

Uncurbed arterials on the Texas Highway Freight Network (THFN) should provide at least 8 ft outside shoulders for these contexts.

Arterials can incorporate all types of speed change lanes including:

Speed change lanes should be provided where vehicles must slow to leave a facility or accelerate to merge onto a facility.

The width of a speed change lane should match the through lane width of the facility. See and refer to for additional guidance on speed change lane widths and their use.

If climbing lanes are warranted, for guidance on climbing lanes see .

For guidance on Parking Lanes, see .

For guidance on Intersections, see .

For guidance on Medians, see .

For guidance on Curbs and Curb Offsets, see .

For guidance on Cross Slope and Superelevation, see and .

For guidance for maximum Grades for local roads, see .

There are typically two primary considerations for roadside design along the traveled way for arterials – clear zones and lateral offset.

Lower-speed arterials in urban and urban core areas should provide a balanced roadway design for all users. These considerations may include providing increased access and mobility for nonmotorized modes (pedestrians, bicyclists, etc.), facilitating transit operations, and achieving other community goals.

Arterials must meet the minimum clear zone requirements shown in . For additional guidance on roadside design see .

For guidance for lateral offset, see .

Bridges, culverts, walls, tunnels, and other structures must be designed in accordance with the current TxDOT . The design loading must be HL-93 design live load unless design for a special vehicle is specified or warranted.

Refer to the latest for additional design guidance for bridges on TxDOT facilities.

For vertical clearance requirements see .

For guidance for grade separations, interchanges, and ramps, see .

Refer to for additional information on grade separations, interchanges, and ramps.

For guidance for Bicycle and Pedestrian Facilities, see and . All projects should be assessed for pedestrian and bicycle accommodations that may be required.

The installation of driveways and all access points along arterial highways must be in accordance with TxDOT’s .

For arterial highways constructed in developed or developing areas, it may be desirable to control access through right-of-way acquisition or by design (i.e., provision of frontage roads). Designed access control may be provided solely within interchange areas or continuously throughout a section of highway, depending on traffic volumes, the degree of roadside development, availability of right-of-way, and economic conditions.

On two-lane arterial highways, frontage roads or parallel service roads to serve small rural business communities or other developments should not be permitted.

To a driver unfamiliar with the local area, a frontage road takes on the appearance of a separate roadway of a multilane divided facility, thus resulting in the assumption that the two-way, two-lane highway is a one-way roadway. Where individual driveways are located within deep cut or high fill areas, driveways may be routed parallel to the highway for short distances to provide for a safe, economical junction with the highway.

All frontage road development must be in accordance with the rules contained in . See for additional information on frontage road access control.