This Chapter identifies the site access improvements required to support proposed entrances and street connections. The function, applications, and geometric design of various site access improvements, including frontage improvements and turning lanes, are discussed in this Chapter. The site access improvements required for different types of development projects, highway functions, and traffic conditions are specified. Some projects may be eligible for exceptions as discussed in 13.11.
The design of State highway improvements for site access shall conform to SHA's Standards and Specifications, the guidelines presented herewith, and engineering practices accepted by SHA. Specific engineering design requirements for improvements within the State's right-of-way are discussed in Chapter 15.
The scope of improvements required by SHA to support the proposed access generally reflects the type and size of the development, the number and location of proposed access points, the anticipated traffic conditions, and the functional requirements, operational characteristics, and geometric conditions of the State highway. The State Highway System designation, highway functional classification, prevailing approach speeds, traffic volumes, driver expectancy, sight distance, adjacent access points, nearby intersections, existing lane markings, and other existing and anticipated geometric conditions on the highway are considered during the review process.
Frontage channelization and related highway improvements may be required for any project, in accordance with 13.3. The construction of barrier curb and gutter along the frontage of developing properties is necessary to delineate the means of vehicular ingress and egress to roadside development. This confines vehicular movements to the permitted entrances, provides an appropriate roadside condition for lower speed highways in urbanized areas, and affords protection for pedestrians on adjacent sidewalk. Along higher speed highways, roadside grading using relatively flat slopes provides an appropriate treatment for the safety of errant vehicles. Curb and gutter may be reduced or eliminated in many rural applications where appropriate roadside grading is feasible.
In any development setting, the necessary highway improvements may include roadside grading, storm drainage, traffic control measures, utility relocation, and adjustment of various highway features. SHA may require the design of frontage improvements to be coordinated with long-term highway plans, local master plans, or other construction projects, thereby reducing or minimizing future impacts, costs, and traffic disruption.
Turning lanes typically include deceleration lanes, acceleration lanes, bypass lanes, and left turn lanes. They may be required in accordance with 13.4 to address right and left turns both in and out of an access point. Turning lanes are an important element of site access improvements in that they allow speed changes and turning maneuvers to occur outside of the normal flow of highway traffic. This reduces the incidence of rear-end collisions at the access point and helps to maintain through traffic flow on the highway. Accordingly, SHA requires turning lanes for public road connections and for commercial sites that will generate appreciable traffic during times of peak travel on the State highway.
Where formal turning lanes are not expressly required by this policy, widening to provide an improved shoulder may be required for any access point to address occasional turning vehicles, in accordance with 13.7. This includes providing new shoulders, widening along existing shoulders, and reconstructing existing shoulders to provide a traffic bearing surface outside of the normal travel lanes of the highway to address occasional turning movements.
The existing highway shall be widened as necessary to support the required frontage channelization, turning lanes, and improved shoulders and provide appropriately designed transitions between improved and unimproved segments of the highway. Applicants are advised that the required widening may extend beyond the developing property frontage. For this reason, the availability of sufficient right-of-way to construct acceptable turning lanes must be considered when determining the location of proposed access. If sufficient right-of-way is not available, SHA may require the applicant to use a different access point location where the normally required features are feasible.
Improvements proposed for a new project shall not adversely affect, diminish, or otherwise compromise the effect of improvements previously constructed for another project, unless specifically authorized by SHA. For example, previously built acceleration and deceleration lanes that serve an existing development may not be eliminated to accommodate a left turn lane into a new development on the opposite site of the highway.
A. Curb and Gutter Limits. Curb and gutter channelization of developing property frontage is required in accordance with Table 13.2.1. Consideration is given to the progression of adjacent land development and build-out of the highway, along with the anticipated ultimate highway typical section, in determining whether full frontage channelization should be required.
B. Exceptions. Channelization may be waived in the following instances, unless a safety issue results:
Substantial speed reduction is normally required by vehicles making right turns into site and subdivision access points. Due to site constraints and practical limitations on their geometric design, the safe operating speed for commercial entrances and street connections is typically in the 5 to 15 mph range. Moreover, limited separation between the highway and on-site traffic patterns may result in vehicle stacking at or near the entrance area. Where vehicles must reduce speed considerably and/or stop in the through lane in order to make right turns into access points, the potential for rear-end collisions is increased.
Deceleration lanes reduce the risk of rear-end collisions by allowing speed reduction and right turns to take place outside of the highway through lanes. Depending on their length, either full or partial speed adjustment can occur within the deceleration lane, thereby reducing speed differentials and associated traffic disruption in the through lanes. The importance of providing for complete speed adjustment is increased with greater right turning and/or approach volumes and higher operating speed. In addition, the function of the highway must be considered. For example, full speed change lanes may be appropriately required for any access along controlled access highways and highly-traveled arterial routes, in order to minimize adverse effects on their capacity and service conditions. In contrast, an improved shoulder may be acceptable, in lieu of a formal deceleration lane, for relatively minor development along low-speed routes that provide a collector function.
Deceleration lanes may be required for any access point wherever deemed necessary, by SHA, to provide acceptable safety and traffic operations on the State highway. In the absence of compelling site-specific considerations, deceleration lanes are required in accordance with the criteria given in Table 13.3.2:
The length of Standard Full Deceleration Lanes and Standard Partial Deceleration Lanes will be as discussed below.
A. Full Deceleration Lanes. The length of Standard Deceleration Lanes is based on AASHTO design for speed change and transition tapers, plus any applicable queuing for right turns into the access point. Right-turn queuing length under the design operating conditions, based on the results of an approved traffic study, is to be added to the required lane length given below. Neglecting queuing, the minimum lengths are as follows for various posted speeds:
B. Partial Deceleration Lanes. The layout of Standard Partial Deceleration Lanes is as follows:
Acceleration lanes allow vehicles turning right, or in some cases left, out of an access point to gain speed before merging into the highway through traffic. Depending on their length, acceleration lanes afford either full or partial speed adjustment outside of the normal travel lanes, contributing to safer operating conditions. Full speed adjustment is most important where a relatively high volume of turning vehicles is expected to freely merge with through traffic at the highway operating speed. In this case, the acceleration lane is vital to the safe and effective operation of the intersection or interchange. Full speed change lanes are also appropriate for controlled access highways and other high-speed, high-volume arterial routes. Partial speed adjustment is sufficient for the vast majority of stop-controlled access points. This practice addresses outbound movements that occur during gaps in through traffic by providing a tapered area for some speed adjustment and merging.
Acceleration lanes may be required for any access point wherever deemed necessary, by SHA, to provide acceptable safety and traffic operations on the State highway. In the absence of compelling site-specific considerations, acceleration lanes are required in accordance with the criteria given in Table 13.4.2.
A. Full Acceleration Lanes. The length of Full Acceleration Lanes will be determined based on the requirements for speed change and applicable weaving/gap acceptance, in accordance with the latest AASHTO guidelines.
B. Partial Acceleration Lanes. The length of Standard Partial Acceleration Lanes will be as follows:
Left turn movements encounter delays while waiting for gaps in opposing traffic, in addition to other vehicles at the intersection or access point. As the volume of opposing traffic increases, left turn delays become a strong possibility at any intersection. Vehicles stopped in the through lanes while waiting to make left turns present multiple safety hazards, causing other vehicles to rapidly stop or change lanes in order to avoid them. Left turn vehicles stopped in a through lane can drastically reduce the safety and service conditions of the highway by increasing the possibility of rear-end collisions and impeding through traffic flow. Accordingly, the volumes of left turning and opposing vehicles are critical factors in the evaluation of intersection capacity, delays, queuing, and traffic signal timing.
As the volume of opposing traffic and/or left-turning vehicles increases, queuing of vehicles waiting to execute left turns is more likely to occur. Left turn lanes substantially improve the safety and operation of intersections and median crossovers on multilane highways. Their design combines the function and benefits of deceleration lanes with storage capacity for queuing of vehicles waiting to make left turns. Left turn lanes allow speed reduction and queue storage to take place outside of the normal travel lanes, thereby reducing the likelihood of rear-end collisions and reducing the disruption of through traffic.
Bypass lanes are often employed on two lane undivided highways to accommodate occasional left turning vehicles at “T” intersections, without affecting the location of existing through lanes. The bypass lane allows through traffic to pass to the right of a vehicle stopped in the normal travel lane while waiting to execute a left turn, while maintaining travel at the posted speed. Where frequent queuing of left turning vehicles may be expected on two-lane highways, a dedicated left turn lane may be necessary instead of a bypass lane. Larger commercial sites and subdivisions, particularly those on higher volume routes, will typically require a dedicated left turn lane as opposed to a bypass lane. In general, left turn lanes are appropriately provided when a 4th leg is introduced to an existing “T” intersection.
Bypass lanes or left turn lanes may be required for any access point wherever deemed necessary, by SHA, to provide acceptable safety and traffic operations on the State highway. The volume of left turning vehicles and the volume of traffic in the opposing travel lane are important but not exclusive factors considered by SHA. The charts in Appendix F may be used as a general indicator of traffic volumes that may warrant a bypass lane or left turn lane.
In the absence of compelling site-specific considerations, bypass lanes or left turn lanes are required in accordance with the criteria given in Table 13.5.2:
Total Length = Taper Length + Deceleration Length + Storage Length
The required deceleration length varies according to the posted speed and functional classification of the highway. This yields the following standards to be applied:
Full Deceleration DesignApplies to:
Partial Deceleration Design Applies to:
NOTE: Refer to 13.3 for discussion and derivation of full and partial deceleration lengths incorporated into the above requirements.
C. Storage Length. The required storage length shall always be consistent with the results of an approved traffic study. Storage length shall be determined from an appropriately supported queuing analysis. For passenger vehicles with arrival times distributed throughout the peak hour, the following formula may be used as a guide:
Queue Storage Length Required = 1.25 X (# of peak hour left turns)
Where a storage length less than 50’ is indicated, the left turn lane lengths given in Table 13.5.3 above will be considered sufficient to address queue storage.
Additional storage length may be required to address school bus, truck, or other commercial vehicle traffic characteristics, as determined by SHA.
D. Lane Shift. When a left turn lane is established on an existing two-lane undivided highway, appropriate lane shift tapers for the through lane movements shall be provided in accordance with the latest version of the MUTCD:
The lane shift taper is a separate requirement, not to be confused with the left turn bay taper discussed in 13.5.3.B
E. Closely Spaced Intersections. Where closely spaced intersections and/or access points would result in overlapping left turn bays and/or lane shift transitions, SHA may require the construction of an extended center turn lane or reduce the required length of the left turn lane. If the minimum queue storage required by 13.5.3.D cannot be achieved by the design, SHA may deny access for the left turn movement.
The layout of Bypass Lanes shall conform to the standards given in this section.
A. Length. The length required for Bypass Lanes varies with the operating speed of the highway and shall be in accordance with Table 13.5.4. Tapers are longer for higher speed highways, to allow for safe lane shifts and clearance from left turning vehicles.
NOTE: Taper lengths are based on the MUTCD taper design for lane shift in temporary traffic control zones,which is one half the length normally required for a permanent through lane shift.
B. Urban Areas. In urban areas, the approach taper may be reduced to 100', with the difference applied to increase the Approach Lane length.
C. Adjacent Intersections. Additional length may be required to form a functional auxiliary lane to address closely spaced street connections and/or commercial entrances along the highway.
D. Reduced Lane Lengths. The length of the approach lane and departure lane portions of the bypass lane may be reduced to 150' and 100', respectively, for the following applications:
E. Use of Existing Turning Lanes. Where there are existing acceleration and/or deceleration lanes serving an access point on the opposite side of the highway, the applicant may be required to upgrade those facilities to function additionally as a bypass lane for the new access. However, the existing turning lanes may not be eliminated or otherwise compromised to support improvements for the new access. Consideration shall be given to establishing opposing left turn lanes instead.
F. Left Turn Lane Alternative. A left turn lane may be approved in lieu of a bypass lane, at SHA's discretion, where a bypass lane would not be feasible or cost-effective. Factors considered include lane shift, highway function, and site-specific traffic and safety conditions. In some cases, a shoulder improvement may be preferable to a left turn lane when a bypass lane is not feasible.
Shoulder improvement is defined as the construction of new shoulders, or widening and reconstruction and/or resurfacing of existing shoulders, to provide a traffic-bearing paved area outside of the normal travel lanes for accommodating turning movements at the proposed site access.
A shoulder improvement may be required where indicated by one or more of the following guidelines:
The length required for a shoulder improvement varies with the intended use, as follows:
*NOTE: Assuming 12' of the available shoulder width is used by turning vehicles, the lengths are approximately 100' and 180' for 8:1 and 15:1 tapers, respectively.
Requirements with respect to the construction or modification of other auxiliary use lanes, such as two-way center turn lanes, continuous auxiliary lanes, and service roads, will be determined by SHA on a case-by-case basis. The design shall be based on AASHTO geometric design guidelines and accepted engineering practices, addressing the anticipated traffic safety and operational conditions.
Where there is limited distance available between successive turning lanes along the highway, extension of the proposed improvements may be required to provide a continuous auxiliary lane. This requirement is most common in urban settings where access points and median crossovers may be closely spaced and along high speed highways with acceleration, deceleration, and left turn lanes having considerable length.
SHA may require the permittee to provide a center turn lane for handling left-turn traffic, where warranted to address traffic impacts from development. Typical applications include urban highways with closely spaced, full movement access points, for which individual left turn bays are not feasible and for which minimal queueing of left turning vehicles is anticipated. While center turn lanes are sometimes established on 2-lane and multilane undivided highways, often through retrofit of new pavement markings, their use will not be considered on divided highways or highways pending construction of a raised median.
Appropriately designed permanent or temporary service road segments may be required in connection with proposed access, where necessary to address future highway needs.
Back curb may be required along the existing or proposed right-of-way line to control access to the State highway right-of-way from the development. The on-site curb and gutter typically required for commercial development is normally sufficient for this purpose, in lieu of a back curb. In rural areas where a drainage ditch of sufficient depth to act as a barrier will remain paralleling the highway, or the height and grade of slope of the property abutting the State highway is greater than 3 feet and 2:l respectively, the back curb (on the right-of-way line) may be eliminated at the discretion of EAPD. If the topography of the area is changed by the owner so that the side ditches or cut slopes are eliminated, a curb or a curb and gutter along the right-of-way will be required.
On-site curb shall be constructed along parking areas, drive aisles, and other areas subject to motor vehicle traffic. It shall be located beyond the ultimate reserved or dedicated right-of-way required for future public road improvements with allowance made for local zoning or setback requirements. EAPD identifies the ultimate section based on SHA planning studies, design plans, or the Highway Needs Inventory, as applicable. When back curb is required instead of on-site curb, the following guidelines apply:
Construction of new or modified highway medians may be required in order to restrict, discourage, or prevent certain turning movements in and/or out of the site. This requirement is determined by evaluating the safety and traffic operations issues presented at each point of access. Median installation and modifications most commonly include:
Requirements will be determined for the specific location on a case by case basis. The design of all medians shall comply with AASHTO geometric design guidelines and SHA standards. Suggested geometric layouts for the most common median openings are provided in the typical details in Appendix C.
Sidewalk along a State highway may be required by SHA, the local government, or both in connection with a request for State highway access. In either case, the sidewalk construction and/or reconstruction along the State highway(s) will be required and included in the Access Permit. Once constructed, sidewalks are maintained and repaired by the political subdivision in which they are located, not by SHA. The design must conform to SHA's and the local government's requirements.
The construction or reconstruction of sidewalks is required in the following instances:
Sidewalk is generally required only along the frontage of the developing property; however, in some instances, it may be required elsewhere along the highway if increased pedestrian travel demand generated by the development causes a safety issue.
The location of the sidewalk shall be determined using practices approved by the appropriate local jurisdiction and/or SHA. Typically, the sidewalk is to be constructed parallel to and behind curb and gutter. A 6’ grass strip between the back of curb and the sidewalk is desirable.
Standard width for sidewalk constructed within the State right-of-way is 5' minimum.
All sidewalk facilities constructed within State right-of-way, regardless of the local jurisdiction's requirements, shall comply with ADA standards and practices. Refer to 13.11 for additional information and reference to guidance documents.
Exceptions to the requirements of this Chapter may be considered for the following applications, upon receipt of proper supporting documentation, which may include a traffic study. Upon review of a properly supported appeal, the decision of EAPD will be final. No further appeals will be considered once this decision is rendered.
If the State highway has less than 2000 ADT and no significant long-term growth in traffic volumes is expected, the scope of site and subdivision access improvements may be reduced at the sole discretion of SHA, upon consideration of the safety and operational impact of the proposed access on a case-by-case basis.
The requirement for construction of dedicated turning lanes to exclusively serve the site access may be waived for development along previously improved highway frontage at the sole discretion of SHA, upon acceptable demonstration of at least one of the following requirements (A, B, or C):
NOTE: The determination of adequate capacity will be made by SHA. The applicant may be required to submit a traffic study in order to facilitate this determination.
Developments in historically, environmentally, or culturally sensitive areas, as determined by SHA, will be evaluated on a case-by-case basis. Widening may be waived or reduced in scope, subject to the same conditions as identified in Section 13.11.2 above. Again, frontage improvements may be required regardless.
The following guidelines may be applied to small-scale commercial development along low (2,000 ADT) to moderate (5,000 ADT) volume highways, at the discretion of SHA, unless a safety issue results:
Access that will have use limited to specific time periods or by specific vehicles, will be evaluated on a case by case basis to determine the scope of site access improvements required. Examples include mining/land reclamation operations, seasonal business operations, temporary business establishments, timber harvesting operations, school bus entrances, loading dock access, telecommunications tower sites, unmanned utility facilities, etc. SHA may require the full scope of improvements normally required in any case.
The requirement for existing site frontage to be improved is determined on a case by case basis for redevelopment projects. The degree to which substandard features or conditions are present, their significance to the safety and operations of the State highway, and the extent to which the redevelopment may exacerbate them, are prime considerations for SHA. Where no compelling safety, capacity, or operational issue exists, the overall scope of the project is the main consideration. Complete site reconstruction generally requires the same improvements as new construction would, whereas minor site renovations to support a different use may only trigger entrance improvements.
From time to time, special situations occur which warrant a restrained approach to the application of access requirements. Relief may be possible for the following situations:
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