Access Management Manual: Frontage Roads

Section 5: Frontage Roads

Overview

This section describes the function and characteristics of freeway frontage roads, including how access connections will be applied along these frontage roads. Frontage roads are roadways that are constructed generally parallel to a freeway or other highway. Figure 2-2 shows a typical frontage road application.

Freeway frontage roads normally have at-grade interchanges with the arterial streets, which are generally perpendicular to the freeway and are grade-separated from the freeway mainlanes. Under fully developed conditions, the at-grade intersections of frontage roads and arterials are typically signalized.

Ramps provide connections between the frontage roads and the freeway. Traffic traveling from an arterial street to the freeway first turns from the arterial onto the frontage road and then travels along the frontage road to a freeway entrance ramp. Traffic traveling from the freeway to an arterial street leaves the freeway by means of an exit ramp that connects to the frontage road and then travels along the frontage road to its intersection with the arterial street.

Other streets may also intersect with frontage roads. By means of these intersections, access is provided between the freeway system and the developments that have access onto these streets.

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Figure 2-2. Freeway with Frontage Roads

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Application of the Criteria

Frontage roads may be considered in order to provide direct access to abutting property where 1) alternative access is not available and the property would otherwise be landlocked, 2) it is not feasible for the Department to purchase the access, and 3) the frontage road allows for improved mobility together with the property access.

Direct access to the frontage road is prohibited in the vicinity of ramp connections, as described in the TxDOT Roadway Design Manual, Chapter 3. Otherwise, on roadways where TxDOT does not control the access, access connecting to the frontage road is typically permitted subject to the access connection criteria set forth in this manual. For application of access connections where TxDOT controls the access, refer to Chapter 2, Section 2, Application of Access Criteria.

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Connection Spacing Criteria for Frontage Roads

Table 2-1 gives the minimum connection spacing criteria for frontage roads. However, a lesser connection spacing than set forth in this document may be allowed without deviation in the following situations:

To keep from land-locking a property where such land-locking is solely the result of action by TxDOT (for example, design and construction modifications which physically prevent a driveway installation due to grade changes, retaining walls, or barrier installations) where TxDOT does not control the access; or
Replacement or re-establishment of reasonable access to the state highway system under highway reconstruction/rehabilitation projects.

The above references to land-locking do not apply to circumstances where an existing larger tract of land is subsequently (after the effective date of this manual) further subdivided (and the subdivided lots sold to separate owners) and the original tract of land either already has an existing permitted access connection point, or would qualify for such an access connection point based upon the spacing requirements of this manual. Potential land-locking caused by subdivision and resale is the result of such subdivision process and will not alone justify variances or deviations in the spacing requirements contained in this manual. Therefore, as part of the subdividing process, the party proposing the subdivision (and the municipality approving such subdivisions) should require and provide some type of internal access easements to the existing access connection points (or to such access connection point locations that qualify for future permits based on this manual's spacing requirements).

It should be noted that for areas with conventional diamond ramp patterns the most critical areas for operations are between the exit ramp and the arterial street and between the arterial street and the entrance ramp. In X-ramp configurations, the most critical areas are between the exit ramp and the subsequent entrance ramp. While Table 2-1 gives minimum connection spacing criteria, the critical areas with respect to the ramp pattern may need greater spacing requirements for operational, safety, and weaving efficiencies.

The distance between access connections is measured along the edge of the traveled way from the closest edge of pavement of the first access connection to the closest edge of pavement of the second access connection (Refer to Figure 2-1). Additionally, the access connection spacing in the proximity of frontage road U-turn lanes will be measured from the inside edge of the U-turn lane to the closest edge of the first access connection (Refer to Figure 2-3)

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Figure 2-3. Frontage Road U-Turn Spacing Diagram

Anchor: #i1002930Table 2- 1: Frontage Road Connection Spacing Criteria
Minimum Connection Spacing Criteria for Frontage Roads(1)(2)
-	Minimum Connection Spacing (feet)
Posted Speed (mph)	One-Way Frontage Roads	Two-Way Frontage Roads
≤ 30	200	200
35	250	300
40	305	360
45	360	435
≥ 50	425	510
Distances are for passenger cars on level grade. These distances may be adjusted for downgrades and/or significant truck traffic. Where present or projected traffic operations indicate specific needs, consideration may be given to intersection sight distance and operational gap acceptance measurement adjustments. When these values are not attainable, refer to the deviation process as described in Chapter 3, Section 1 or Chapter 2, Section 2.