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21st Century Operations Using 21st Century Technologies

Use of Freeway Shoulders for Travel — Guide for Planning, Evaluating, and Designing Part-Time Shoulder Use as a Traffic Management Strategy

Chapter 8. Implementation Process

This chapter presents “how to” information to help agencies implement part-time shoulder use once a decision to use it has been made. The chapter will also help agencies still in the planning stages understand the steps generally taken to implement part-time shoulder use.

Design Exception Process

States are required to obtain design exceptions from Federal Highway Administration (FHWA) if the minimum values of the controlling criteria presented in the Geometric Design section of Chapter 7 of this Guide are not met on roadways that are part of the National Highway System. Part-time shoulder use may impact a number of the controlling criteria, and by definition it impacts shoulder width when the shoulder is open. AASHTO standards require a minimum freeway lane width of 12 feet and a minimum freeway shoulder width of 10 feet (except the left shoulder of 4-lane freeways, which has a minimum width of 4 feet). Therefore, unless an existing shoulder is at least 22 feet wide (or 16 feet wide in the case of a left shoulder on a 4-lane freeway), a design exception will be required when static or dynamic part-time shoulder use is implemented. Design exception practices for bus-on-shoulder (BOS) vary.

The key piece of a design exception request is an explanation of why it is infeasible to meet AASHTO standards. Meeting standards on part-time shoulder use is equivalent to conventional widening, and part-time shoulder use is likely being considered because conventional widening is infeasible in terms of cost or right-of-way (ROW) requirements.

Design exception requests should also include an evaluation of the implications of substandard features and how they are mitigated on a specific facility. In the case of part-time shoulder use, the following may mitigate substandard geometry:

  • Reduced speeds, achieved through lower speed limits of periods of shoulder operation coinciding with congestion.
  • Annual average daily traffic (AADT) in ranges where Highway Safety Manual (HSM) analysis, summarized in CHAPTER 4, predicts a reduction in crashes with narrowing of the shoulder and addition of a lane.
  • Use on commuter facilities during commuting periods with a high percentage of familiar drivers.
  • Prohibition of trucks from the shoulder.
  • Extensive monitoring of the facility with ITS and/or patrol vehicles.
  • Variable lane controls allowing closure of the shoulder if it is blocked by a disabled vehicle.
  • Emergency turnouts.
  • The potential for a performance-based practical design (PBPD) approach where the savings associated with not constructing a conventional lane are used on other projects that improve network operations and safety.

The specific requirements of design exception requests vary by state. Design exceptions are typically submitted to and approved by FHWA Division Offices, although they may allow approval on their behalf by state departments of transportation (DOTs) or local agencies.(50) Part- time shoulder use may have a relatively short implementation timeframe compared to conventional projects, so a design exception request should be prepared and submitted to FHWA as early as possible in the planning process. Design exception requests are typically reviewed in conjunction with the overall review and approval of the plans, specifications, and estimates, which may be relatively minor for part-time shoulder use.(50)

FHWA approval process for part-time shoulder use has varied. In Massachusetts, approval was granted on a temporary basis when part-time shoulder use was first implemented in 1985 and renewed several times before permanent approval was granted in 2009.(49)

Most part-time shoulder use projects that have recently been implemented or are currently in the planning process are long-term implementations. Temporary approval is not recommended because it creates the need for re-approval.

Many states also have design standards, manuals, or laws that may need to be updated prior to implementing part-time shoulder use. Minnesota, which has nearly 300 miles of BOS facilities, developed standards for BOS facilities in the 1990s with input from their FHWA Division Offices.(44) The standards were incorporated into MnDOT’s design manual. Washington State, which is planning several part-time shoulder use and Active Traffic Management (ATM) installations, is developing an urban freeway retrofit guide with the help of their FHWA Division Office.(33)

Legal Issues

In some states, driving on the shoulder is prohibited by law, and implementation has required legislative action or new rulemaking and agreements to interpret existing laws. For example:(42)

  • Minnesota amended their statutes in 2005 to “formalize” BOS operation. Previously, there was an agreement between the state patrol, Metro Transit, and the DOT.
  • Florida DOT created an inter-local agreement with the Miami-Dade Transit in which BOS was treated as a pilot project.
  • California defined shoulders as transit lanes to legally enable a BOS pilot project in San Diego in the mid-2000s (the project has since ended).
  • Georgia DOT authorized BOS as a demonstration project.

MUTCD Experimental Approval Process

If “a new traffic control device or a different application of an existing device” is “not compliant with or not included in the MUTCD”, the state DOT considering its installation should submit a request to experiment to FHWA MUTCD team, and FHWA must approve the experiment before the control device is installed.

Most part-time shoulder use projects have not used experimental traffic control devices. Control devices commonly used on part-time shoulder uses facilities that do not require experimental approval include the following:

  • Regulatory signs indicating the hours of operation of a shoulder lane
  • Warning signs on on-ramps or along part-time shoulder use segments that notify drivers of part-time shoulder uses
  • Signs indicating vehicle restrictions of part-time shoulder uses, such as no trucks or buses only
  • Green arrow and red “x” dynamic lane control signs
  • A second edge line between the outside of the shoulder and edge of pavement or median barrier
  • Dotted pavement markings at ramp-freeway junctions and the start and end of part-time shoulder use segments to guide drivers when the shoulder is open and closed

However, more-complex part-time shoulder use projects, such as those with other ATM
elements, may require a request for experimentation.

The request for experimentation should originate with the State DOT and be sent to FHWA Headquarters with a courtesy copy to the FHWA Division Office. The FHWA must approve the experiment before it begins. All requests should include the following:(51)

  • A statement of the nature of the problem, including data that justifies the need for a new application.
  • A description of the proposed change, how it was developed, and how it deviates from the current MUTCD.
  • Any illustration(s) that enhances understanding of the device or its use.
  • Supporting data that explains how the experimental device was developed, if it has been tried, the adequacy of its performance, and the process by which the device was chosen or applied.
  • A legally binding statement certifying that the concept of the traffic control device is not protected by a patent or copyright.
  • The proposed time period and location(s) of the experiment.
  • A detailed research or evaluation plan providing for close monitoring of the experimentation, especially in the early stages of field implementation. The evaluation plan should include before and after studies as well as quantitative data enabling a scientifically sound evaluation of the performance of the device.
  • An agreement to restore the experimental site to a condition that complies with the provisions of the MUTCD within 3 months following completion of the experiment. The agreement must also provide that the sponsoring agency will terminate the experiment at any time if it determines that the experiment directly or indirectly causes significant safety hazards. If the experiment demonstrates an improvement, the device or application may remain in place until an official rulemaking action occurs.
  • An agreement to provide semi-annual progress reports for the duration of the experimentation and a copy of the final results to the FHWA's Office of Transportation Operations within three months of the conclusion of the experiment.

Stakeholder Engagement

Successful deployment of part-time shoulder use requires a well-planned, interdisciplinary collaboration with a variety of different stakeholders, including planning, operations, design, maintenance, and executive leadership staff within a DOT; law enforcement; emergency responders; bus operators; MPO staff; and FHWA Division Office staff.

A state DOT will typically be the agency that decides if part-time shoulder use is feasible, possibly in collaboration with a transit agency if BOS is under consideration. As soon as this determination is made, the state DOT should reach out to the stakeholder groups noted above and form a working group. Most agencies that have successfully implemented part-time shoulder use have formed working groups to ensure the needs of all stakeholders are incorporated into the concept of operations. Stakeholder involvement and education—assuming that some stakeholders may not be aware of the benefits and potential issues associated with part-time shoulder uses—is an ongoing process and working groups should continue to meet during the early years of a part-time shoulder use facility’s operation. Engaging executive leadership early is critical because policies may need to change and laws potentially prohibiting driving on the shoulder may need to be interpreted or changed.

For stakeholders who do not have a working knowledge of part-time shoulder use, implementing an education and outreach program during the early stages of the effort will help build trust in the proposed investments. This education and outreach effort can include peer exchanges, involving counterparts from other states or countries with shoulder running experience, as well as FHWA.

The traveling public is also an important stakeholder, and their engagement is discussed later in this chapter.

Incorporating and Mitigating Emergency Response and Incident Management Concerns

Emergency responders frequently drive on shoulders to reach incident scenes and use shoulders to park while responding to incidents. Concerns over the potential loss of the ability to bypass congested traffic and remain out of the travelled way when responding to incidents need to be addressed before part-time shoulder use is implemented, particularly for longer part-time shoulder use sections spanning multiple interchanges.

Incident response plans developed during the planning of part-time shoulder use can mitigate these concerns. “Sweeps” of the shoulder before it opens and the construction of turnouts reduce the likelihood of the shoulder being blocked. A fleet of dedicated incident response vehicles positioned at multiple locations along the facility can also decrease incident response times.

If dynamic signs are used, additional incident management and response options are available. Local emergency response agencies should be given the authority to order the closure of the shoulder and have a clear line of communication to the TMC for doing so. Closing the shoulder clears it of vehicles and provides emergency responders with an uncongested path to incident scenes.

Incorporating and Mitigating Maintenance Concerns

Maintenance concerns with part-time shoulder use typically relate to how the lane designated for part-time shoulder use should be maintained—more similar to a shoulder or more similar to a travel lane, how existing maintenance activities will be impacted, and what new maintenance activities will be required.

Agencies with part-time shoulder use have generally come to the conclusion that shoulders should be maintained in the same manner as other lanes, and nothing outside of typical maintenance operations needs to be done with regard to filling potholes, plowing snow, and so forth. Existing maintenance activities requiring stopping on the shoulder cannot occur when the shoulder is open but are otherwise unaffected.

New maintenance needs vary greatly depending on the type of part-time shoulder use. BOS and static part-time shoulder uses with no additional ITS have virtually no additional maintenance needs beyond maintaining the shoulder as a lane. Extensive ITS hardware used for dynamic part- time shoulder use and other ATM systems likely require additional maintenance staff and staff training with regard to the specifics of the technology.

Incorporating and Mitigating Bus Operator Concerns

Minnesota began widespread implementation of BOS operation in the Twin Cities metropolitan area in the 1990s. Their methods of mitigating bus operator concerns are well-established and have served as a model for many other states that have subsequently implemented BOS.

On routes designated for BOS, Minnesota limits BOS speed to 15 mph faster than adjacent traffic and an absolute maximum of 35 mph. This ensures BOS occurs in a relatively low-speed environment with low speed differentials. The choice to use the shoulder is up to each driver, although passengers sometimes complain if speeds are low enough to permit part-time shoulder use and drivers choose not to use it. Metro Transit, the largest bus operator in the Twin Cities, allows drivers who are uncomfortable driving on the shoulder to request transfers to other routes. The primary requirement for a bus using the BOS lanes is for the driver to have received training. Transit agencies using the BOS lanes offer training several times a year, and new drivers are assigned to routes without BOS if they have not yet been trained.


Similar to other innovative transportation projects, public outreach is a critical part of part-time shoulder use implementation. Successful implementation of the first part-time shoulder use project in a metropolitan area includes explicit and proactive outreach and education to the general public and should be undertaken consistent with state public information guidance. This would create opportunities to familiarize others with the concept of part-time shoulder use and the details of how it will work on a specific facility. How will drivers know if the shoulder is open or closed? What special signs will be used? Will the speed limit change? What should drivers do if they break down? Creating multiple forums to engage the public (including presentations at local council or board meetings, briefs at community organization functions, and project-specific open house meetings) results in opportunities to listen to community interests and share objective information about part-time shoulder use.

Public outreach conducted during planning a part-time shoulder use project can inform and educate the public about proper use and benefits. Media campaigns through local newspapers, television, and public meetings can be effective methods of keeping the community informed. Once the part-time shoulder use project is open to the public, monitoring driver behavior and using law enforcement as necessary to promote proper use of the part-time shoulder use can aid driver acclimation. Figure 39 shows a postcard handout that has been used at public meetings in Michigan in preparation for an ATM installation.

PConceptual illustration of a postcard handout from Michigan DOT. The image on the card depicts the theoretical AM peak operation of part-time shoulder lanes via a cross-section of the roadway. Two traditional travel lanes are present in each direction, with a full-depth part-time shoulder lane provided in each direction on the inside (adjacent to the median). Lane control signs are mounted over each travel lane and shoulder lane. In the AM operation scheme, all three lane-control signs display a steady downward green arrow in the southbound direction; a steady red ‘X is displayed over the northbound shoulder lane and steady downward green arrows are displayed over the northbound travel lanes.

Figure 39. Example Dynamic Part-time Shoulder Use Public Information Material
(Source: Michigan Department of Transportation)

The following communications and public involvement elements may be considered as part of the public outreach:

  • Expect opposition and confusion
  • Understand your non-technical audience
  • Define and identify success
  • Manage expectations
  • Demonstrate public accountability
  • Tell an engaging story
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