View source for 616.3 Temporary Traffic Control Elements (MUTCD Chapter 6C)

==616.3.1 Temporary Traffic Control Plans (MUTCD Section 6C.01)==

'''Support.''' A TTC plan describes TTC measures to be used for facilitating road users through a work zone or an incident area.  TTC plans play a vital role in providing continuity of effective road user flow when a work zone, incident, or other event temporarily disrupts normal road user flow.  Important auxiliary provisions that cannot conveniently be specified on project plans can easily be incorporated into Special Provisions within the TTC plan.

TTC plans range in scope from being very detailed to simply referencing typical drawings contained in this article, standard approved highway agency drawings and manuals, or specific drawings contained in the contract documents.  The degree of detail in the TTC plan depends entirely on the nature and complexity of the situation.

A Traffic Control Plan (TCP) is developed for every project. The TCP is an integral part of the planning and design of a project. The scope of the TCP is determined by the complexity of the project and is developed by the designer in the district in cooperation with district construction, maintenance and traffic personnel. Typical traffic control set-ups shall be shown for each work activity within the work zone. A preliminary field check with district construction and traffic is recommended to ensure the TCP will be compatible with field conditions. 

In some cases, it may be necessary to obtain traffic count data from Transportation Planning to aid in the development of the TCP. This is especially the case where traffic capacity is a significant factor in the design of the TCP. Intersection traffic count data may also be requested from district traffic personnel. Hourly volumes can assist in determining the type of traffic control used, working hour restrictions and other aspects of the TCP. The use of Highway Capacity Software, VISSIM, CORSIM or other computer programs may aid in estimating queue lengths, delays, etc. resulting from the work zone. 

Traffic control sheets must be provided in the traffic control plans showing the location of all traffic control devices.

===616.3.1.1 Typical Applications===

The figures in this article include [[616.8 Typical Applications (MUTCD 6H)|typical applications]] and examples of work zone traffic control. Since each project is unique, the figures cannot address every situation. The typical layouts are to be used as much as possible in developing the TCP and may be adjusted to fit conditions using sound engineering judgment. 

There are many items of work considered incidental. These incidental items are not to have a pay item included in the plans since their cost is included in the larger activity they are associated with. 

===616.3.1.2 Special Provisions===

The [[616.14 Work Zone Safety and Mobility Policy|“Work Zone Traffic Management Plan”]] special provision is required with all plans. This special provision can be modified to include job specific conditions. The purpose of this special provision is not to call the contractor's attention to the standard specifications or to reinforce the standard plans. Construction phases or stages are not to be included in this special provision. A job special provision is to be created by the district for any traffic control items not covered in the plans, standard plans or standard specifications, coordinated with the Design and Traffic Divisions.

On all interstate projects with full FHWA oversight, the district shall submit a set of traffic control plans and associated JSPs to FHWA for review and approval. The district is to submit a complete set of traffic control plans and associated JSPs to Design, 14 weeks prior to the bid opening date (refer to [[:Category:121 Project Planning, Prioritization and STIP Commitments|EPG 121 Project Planning, Prioritization and STIP Commitments]]). Upon approval, FHWA will send an approval letter to the district with a copy to the Design Division. 

'''Guidance.''' TTC plans should be prepared by persons knowledgeable (for example, trained and/or certified) about the fundamental principles of TTC and work activities to be performed.  The design, selection, and placement of TTC devices for a TTC plan should be based on engineering judgment.

The designer is to become familiar with [https://www.modot.org/media/16887 Standard Plans 612.20], [https://www.modot.org/media/16892 616.10], [https://www.modot.org/media/16893 617.10], [https://www.modot.org/media/16894 617.20] and [https://www.modot.org/media/16895 619.10] and [http://www.modot.org/business/standards_and_specs/SpecbookEPG.pdf#page=9 Sections 612], [http://www.modot.org/business/standards_and_specs/SpecbookEPG.pdf#page=9 616], [http://www.modot.org/business/standards_and_specs/SpecbookEPG.pdf#page=9 617] and [http://www.modot.org/business/standards_and_specs/SpecbookEPG.pdf#page=9 619] of the Standard Specifications before preparing the traffic control plan.

Coordination should be made between adjacent or overlapping projects to check that duplicate signing is not used and to check compatibility of traffic control between adjacent or overlapping projects.

When staged construction is used, the stages are to be clearly defined in the TCP. Each stage is to have a description of the type of work being done during that phase. Stationing is to be shown, if applicable.

Traffic control planning should be completed for all highway construction, utility work, maintenance operations, and incident management including minor maintenance and utility projects prior to occupying the TTC zone.  Planning for all road users should be included in the process.

Provisions for effective continuity of accessible circulation paths for pedestrians should be incorporated into the TTC process.  Where existing pedestrian routes are blocked or detoured, information should be provided about alternative routes that are usable by pedestrians with disabilities, particularly those who have visual disabilities.  Access to temporary bus stops, travel across intersections with accessible pedestrian signals (see [http://epg.modot.org/index.php?title=902.6_Pedestrian_Control_Features_%28MUTCD_Chapter_4E%29#902.6.9_Accessible_Pedestrian_Signals_and_Detectors_.E2.80.93_General_.28MUTCD_Sections_4E.09_-_4E.13.29 EPG 902.6.9]), and other routing issues should be considered where temporary pedestrian routes are channelized.  Barriers and channelizing devices that are detectable by people with visual disabilities should be provided.

'''Option.''' Provisions may be incorporated into the project bid documents that enable contractors to develop an alternate TTC plan.

Modifications of TTC plans may be necessary because of changed conditions or a determination of better methods of safely and efficiently handling road users.

'''Guidance.''' This alternate or modified plan should have the approval of the responsible highway agency prior to implementation.

Provisions for effective continuity of transit service should be incorporated into the TTC planning process because often public transit buses cannot efficiently be detoured in the same manner as other vehicles (particularly for short-term maintenance projects).  Where applicable, the TTC plan should provide for features such as accessible temporary bus stops, pull-outs, and satisfactory waiting areas for transit patrons, including persons with disabilities, if applicable (see [http://epg.modot.mo.gov/index.php?title=643.4_Railroads#643.4.4.8_Temporary_Traffic_Control_Zones_.28MUTCD_Section_8A.08.29 EPG 643.4.4.8]) for additional light rail transit issues to consider for TTC).

Provisions for effective continuity of railroad service and acceptable access to abutting property owners and businesses should also be incorporated into the TTC planning process.

Contractors are allowed to reuse traffic control devices from job to job, so designers are not to specify all devices on any particular job shall be new. 

Reduced speed limits should be used only in the specific portion of the TTC zone where conditions or restrictive features are present.  However, frequent changes in the speed limit should be avoided. Further work  zone speed limit information is located in [[616.12 Work Zone Speed Limits|EPG 616.12 Work Zone Speed Limits]].

==616.3.2 Temporary Traffic Control Zones (MUTCD 6C.02)==

'''Support.''' A TTC zone (plan) is an area of a highway where road user conditions are changed because of a work zone, an incident zone, or a planned special event through the use of TTC devices, uniformed law enforcement officers or other authorized personnel.

A work zone is an area of a highway with construction, maintenance, or utility work activities.  A work zone is typically marked by signs, channelizing devices, barriers, pavement markings and/or work vehicles.  It extends from the first warning sign or high-intensity rotating, flashing, oscillating, or strobe lights on a vehicle to the END ROAD WORK sign or the last TTC device.

An incident zone is an area of a highway where temporary traffic controls are imposed by authorized officials in response to a traffic incident (see [[616.9 Control of Traffic Through Traffic Incident Management Areas (MUTCD 6I)#616.9.1 General (MUTCD 6I)|EPG 616.9.1]]).  It extends from the first warning device (such as a sign, light, or cone) to the last TTC device or to a point where road users return to the original lane alignment and are clear of the incident.

A planned special event often creates the need to establish altered traffic patterns to handle the increased traffic volumes generated by the event.  The size of the TTC zone associated with a planned special event can be small, such as closing a street for a festival, or can extend throughout a municipality for larger events.  The duration of the TTC zone is determined by the duration of the planned special event.

==616.3.3 Components of Temporary Traffic Control Zones (MUTCD 6C.03)==

'''Support.''' Most TTC zones are divided into four areas: the advance warning area, the transition area, the activity area (which includes workspace and buffer spaces) and the termination area.  Figure 616.3.3 illustrates these four areas.  These four areas are described in EPG 616.3.4 through EPG 616.3.7.

[[image:616.3.3.jpg|center|590px|thumb|<center>'''Fig. 616.3.3, Components of a Temporary Traffic Control Zone  (MUTCD Fig. 6C-1)'''</center>]]

==616.3.4 Advance Warning Area (MUTCD 6C.04)==

'''Support.''' The advance warning area is the section of highway where road users are informed about the upcoming work zone or incident area.

'''Option.''' The advance warning area may vary from a single sign or high-intensity rotating, flashing, oscillating or strobe lights on a vehicle to a series of signs in advance of the TTC zone activity area.  The signs or other warning devices are positioned to give the driver sufficient time to react to the conditions.  Warning devices are not to be placed too far in advance, as the warning message will lose effectiveness.

In some cases on high volume routes, traffic backups due to the work activity may extend past the normal advance warning area. In this case, additional signing may be required to warn drivers before they reach the backup. For longer-term activities, alternate route signing and interactive devices or changeable message signs may be considered. Computer programs are available to aid in estimating back ups and delays due to work zones. 

In some cases, particularly in urban areas, the advance warning area may extend through an intersection or interchange. Special considerations such as additional advance signs or adjustments to sign spacing may be needed to assure all approaching drivers are informed of the conditions. 

'''Guidance.''' Typical distances for placement of advance warning signs are located in Table 616.3.4 Recommended Advance Warning Sign Minimum Spacing.

The distances contained in Table 616.3.4 are approximate, are intended for guidance purposes only, and should be applied with engineering judgment.  These distances should be adjusted for field conditions, if necessary, by increasing or decreasing the recommended distances.

'''Support.''' The need to provide additional reaction time for a condition is one example of justification for increasing the sign spacing.  Conversely, decreasing the sign spacing might be justified in order to place a sign immediately downstream of an intersection or major driveway so that traffic turning onto the roadway in the direction of the TTC zone will be warned of the upcoming condition.

'''Option.''' Advance warning may be eliminated when the activity area is sufficiently removed from the road users’ path so that it does not interfere with the normal flow.

===<center>Table 616.3.4  Recommended Advance Warning Sign Minimum Spacing</center> ===
<center>
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" style="text-align:center"
|+ 
! style="background:#BEBEBE" rowspan="2"|Speed Limit<sup>'''1'''</sup>, mph!!style="background:#BEBEBE" colspan="2"|Sign Spacing<sup>'''2'''</sup>, ft.
|-
!style="background:#BEBEBE" |Undivided Highway!! style="background:#BEBEBE"|Divided Highway
|-
|up to 35||	200<sup>'''3'''</sup>||	200<sup>'''3'''</sup>
|-
|40 to 45||	350||	500
|-
|50 to 55||	500||	1000
|-
|60 to 70||1000||SA-1000<br/>SB-1500<br/>SC-2640
|-
|align="left" colspan="3"|<sup>'''1'''</sup> Speed limit is based on posted speed limit.
|-
|align="left" colspan="3"|<sup>'''2'''</sup> Sign spacing may be adjusted, normally by increasing it, to accommodate field conditions and visibility.
|-
|align="left" colspan="3"|<sup>'''3'''</sup> For urban low speed, minimum recommended spacing in MUTCD is 100 ft.
|}
</center>

==616.3.5 Transition Area (MUTCD 6C.05)==

'''Support.''' The transition area is that section of highway where road users are redirected out of their normal path.  Transition areas usually involve strategic use of tapers, channelizing devices, signing, pavement marking and other traffic control devices which because of their importance are discussed separately in detail.

'''Standard.''' When redirection of the road users’ normal path is required, they shall be directed from the normal path to a new path.

'''Option.''' Because it is impractical in mobile operations to redirect the road user’s normal path with stationary channelization, more dominant vehicle-mounted traffic control devices, such as arrow boards, portable changeable message signs, and high-intensity rotating, flashing, oscillating or strobe lights, may be used instead of channelizing devices to establish a transition area.

There are three types of tapers: shoulder, lane and one-lane, two-way. 

:* The shoulder taper is used to close the shoulder where it is part of the activity area or when improved shoulders might be mistaken for a driving lane. 

:* The lane taper is used to close a driving lane by forcing traffic to merge. 

Recommended taper length and channelizer spacing for shoulder and lane tapers in the transition area are shown in Table 616.3.5 Recommended Taper Length and Spacing. 

The one-lane, two-way taper is used to close one lane of a two-lane, undivided highway where the remaining lane is used alternately by traffic in each direction. The taper should have a length of 100 ft. (5 channelizers at 20 ft. spacing). In addition to the channelizers, a flagger, STOP or YIELD sign, pilot car or temporary traffic signal controls traffic through this section.

Additional taper information is located in [[#616.3.8 Tapers (MUTCD 6C.08)|EPG 616.3.8 Tapers]].

===<center>Table 616.3.5 Recommended Taper Length and Spacing</center>===
<center>
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" style="text-align:center"
|+ 
! style="background:#BEBEBE" rowspan="2"|Speed Limit<sup>'''1'''</sup>, mph!!style="background:#BEBEBE" colspan="2"|Taper Length<sup>'''2'''</sup>, ft. !!style="background:#BEBEBE" colspan="2"| Channelizing Spacing <sup>'''3'''</sup>, ft.
|-
!style="background:#BEBEBE"| Shoulder<sup>'''4'''</sup> (T1)!!style="background:#BEBEBE"|Lane<sup>'''5'''</sup> (T2)!!style="background:#BEBEBE"|Tapers!!style="background:#BEBEBE"|Buffer/Work Areas
|-
|up to 35||70||	245||	35<sup>6</sup>	||40<sup>6</sup>
|-
|40 to 45||150||	540||	40<sup>6</sup>||	80<sup>6</sup>
|-
|50 to 55||185||	660||	50<sup>7</sup>||	80<sup>7</sup>
|-
|60 to 70||235||	840||	60<sup>7</sup>||	120<sup>7</sup>
|-
|align="left" colspan="5"|<sup>'''1'''</sup> Speed limit is based on posted speed limit.
|-
|align="left" colspan="5"|<sup>'''2'''</sup> Taper lengths may be adjusted to accommodate crossroads, curves, intersections, ramps or other geometric features.
|-
|align="left" colspan="5"|<sup>'''3'''</sup> Channelizer spacing may be reduced to discourage traffic encroachment.
|-
|align="left" colspan="5"|<sup>'''4'''</sup> Based on 10 ft. shoulder width.
|-
|align="left" colspan="5"|<sup>'''5'''</sup> Based on 12 ft. lane width.
|-
|align="left" colspan="5"|<sup>'''6'''</sup> Spacing reduced to 1/2 at intersections.
|-
|align="left" colspan="5"|<sup>'''7'''</sup> Spacing may be reduced to 1/2 at intersections.
|}
</center>

==616.3.6 Activity Area (MUTCD 6C.06)==

'''Support.''' The activity area is the section of the highway where the work activity takes place.  It is comprised of the work space, the traffic space and the buffer space.

===616.3.6.1 Workspace===

'''Support.''' The work space is that portion of the highway closed to road users and set aside for workers, equipment, and material, and a protective vehicle if one is used upstream.  Work spaces are usually delineated for road users by channelizing devices or, to exclude vehicles and pedestrians, by temporary barriers.
[[image:616.1.3.3.1 Workspace.jpg|left|400px]]

'''Option.''' The work space may be stationary or may move as work progresses.

'''Guidance.''' Since there might be several work spaces (some even separated by several miles) within the project limits, each work space should be adequately signed to inform road users and reduce confusion.

'''Option.'''
The workspace may be supplemented by channelizers and/or barricades placed perpendicular to the flow of traffic to deter non-construction related use of closed lanes. The longitudinal spacing and location of these devices are to be developed with the length of the closed lanes, work being performed and roadway characteristics in mind. For example, a longitudinal spacing of twice the normal sign spacing may be used for a paving operation on a limited access roadway, while the devices may be located upstream of a pavement repair area on the same type of facility. See [https://epg.modot.org/files/6/6d/616.8.48_MT.pdf Typical Application 616.8.48 (TA-48) Intermediate Lane Closure – DE/CM & MT].

===616.3.6.2 Traffic Space===

'''Support.''' The traffic space is the portion of the highway in which road users are routed through the activity area.  It is important that the driver is clearly guided into and through the traffic space.

===616.3.6.3 Buffer Space===

'''Support.''' The buffer space is a lateral and/or longitudinal area that separates road user flow from the work space or an unsafe area and might provide some recovery space for an errant vehicle.

'''Guidance.''' Neither work activity nor storage of equipment, vehicles, or material should occur within a buffer space.

'''Option.''' Buffer spaces provide a recovery space for an errant vehicle. Buffer spaces may be positioned either longitudinally or laterally with respect to the direction of road user flow.  The activity area may contain one or more lateral or longitudinal buffer spaces.

A longitudinal buffer space may be placed in advance of a work space.

The longitudinal buffer space may also be used to separate opposing road user flows that use portions of the same traffic lane, as shown in Fig. 616.3.6 Types of Tapers and Buffer Spaces.

[[image:616.3.6.jpg|center|590px|thumb|<center>'''Fig. 616.3.6, Types of Tapers and Buffer Spaces (MUTCD Fig. 6C-2)'''</center>]]

If a longitudinal buffer space is used, the values shown in Table 616.3.6 Recommended Length of Longitudinal Buffer Spaces may be used to determine the length of the longitudinal buffer space.

'''Support.''' Typically, the buffer space is formed as a traffic island and defined by channelizing devices.

When a shadow vehicle, arrow board, or changeable message sign is placed in a closed lane in advance of a work space, only the area upstream of the vehicle, arrow board, or changeable message sign constitutes the buffer space.

'''Option.''' The lateral buffer space may be used to separate the traffic space from the work space, as shown in Figs. 616.3.3 and 616.3.6, or such areas as excavations or pavement-edge drop-offs.  A lateral buffer space also may be used between two travel lanes, especially those carrying opposing flows.

'''Guidance.''' The width of a lateral buffer space should be determined by engineering judgment.

'''Option.''' When work occurs on a high-volume, highly congested facility, a vehicle storage or staging space may be provided for incident response and emergency vehicles (for example, tow trucks and fire apparatus) so that these vehicles can respond quickly to road user incidents.  This may involve providing storage space at the beginning or end of the activity area or both.  This storage is not to extend into any portion of the buffer space.

===616.3.6.4 Side Road Tapers===

'''Option.''' Traffic entering the work zone from side roads may be provided guidance to the open driving lane. Two tapers of 100 ft. per lane with a device spacing of 20 ft. may be placed at the side road entrance. 


====Table 616.3.6 Recommended Length of Longitudinal Buffer Spaces====

<center>
{| border="1" class="wikitable" style="margin: 1em auto 1em auto"
|+ 
! style="background:#BEBEBE"|Posted Speed Prior to Construction, mph!! style="background:#BEBEBE"|Length, ft.
|-
| align="center"| up to 35 ||	 align="center"|250
|-
| align="center"|40 to 45||	 align="center"|360
|-
| align="center"|50 to 55||	 align="center"|495
|-
| align="center"|60 to 70||	 align="center"|730
|}
</center>

==616.3.7 Termination Area (MUTCD 6C.07)==

'''Support.''' The termination area is the section of the highway where road users are returned to their normal driving path.  The termination area extends from the downstream end of the work area to the last TTC device This area may include a downstream (closing) taper or a sign informing traffic they may return to normal operations such as END ROAD WORK signs, if posted.

'''Option.''' An END ROAD WORK sign, a Speed Limit sign, or other signs may be used to inform road users that they can resume normal operations.

A longitudinal buffer space may be used between the work space and the beginning of the downstream taper.
 
==616.3.8 Tapers (MUTCD 6C.08)==

'''Option.''' Tapers may be used in both the transition and termination areas.  Whenever tapers are to be used in close proximity to an interchange ramp, crossroads, curves, or other influencing factors, the length of the tapers may be adjusted.

'''Support.''' Tapers are created by using a series of channelizing devices and/or pavement markings to move traffic out of or into the normal path.  Types of tapers are shown in Fig. 616.3.6.

Taper lengths may be adjusted whenever they are located close to a crossroad, curve, intersection, ramp or other geometric feature. 

Longer tapers are not necessarily better than shorter tapers (particularly in urban areas with characteristics such as short block lengths or driveways) because extended tapers tend to encourage sluggish operation and to encourage drivers to delay lane changes unnecessarily.  The test concerning adequate lengths of tapers involves observation of driver performance after TTC plans are put into effect.

===616.3.8.1 Taper Length===

'''Guidance.''' The appropriate shoulder or lane taper length (T1 or T2) should be determined using the criteria shown in [[#Table 616.3.5 Recommended Taper Length and Spacing|Table 616.3.5]].

The maximum distance in feet between devices in a taper should not exceed the limits in Table 616.3.5.

===616.3.8.2 Merging Tapers===

'''Support.''' A merging taper requires the longest distance because drivers are required to merge into common road space.

'''Guidance.''' A merging taper should be long enough to enable merging drivers to have adequate advance warning and sufficient length to adjust their speeds and merge into an adjacent lane before the downstream end of the transition.

Merging tapers are used to close a lane or combine traffic lanes on multilane facilities. It is important to provide full-length tapers (T2) where practical. For long-term operations, lane line markings are removed through the merging taper and temporary edge lines are to be provided to guide drivers through the taper and the work area.

===616.3.8.3 Shifting Tapers===

'''Support.''' A shifting taper is used when a lateral shift is needed.  When more space is available, a longer than minimum taper distance can be beneficial.  Changes in alignment can also be accomplished by using horizontal curves designed for normal highway speeds.

'''Guidance.''' A shifting taper should have a length of approximately 1/2 (T2) (see [[#Table 616.3.5 Recommended Taper Length and Spacing|Table 616.3.5 Recommended Taper Length and Spacing]]).  Where 1/2 (T2) shifting tapers are used, REVERSE CURVE or REVERSE TURN signs, along with any required advisory speed plaques, are to be posted prior to the shift. For long-term operations, conflicting pavement markings are removed and temporary markings provided to guide drivers through the tapers and work area. For short-term operations where it is not practical to modify pavement markings, a device spacing of 10 ft. is used.

===616.3.8.4 Shoulder Tapers===

'''Support.''' A shoulder taper might be beneficial on a high-speed roadway where shoulders are part of the activity area and are closed, or when improved shoulders might be mistaken as a driving lane.  In these instances, the same type, but abbreviated, closure procedures used on a normal portion of the roadway can be used.

'''Guidance.''' If used, shoulder tapers should have a length of approximately T1 (see [[#616.3.5 Transition Area (MUTCD 6C.05)|EPG 616.3.5 Transition Area]]).  If a shoulder is used as a travel lane, either through practice or during a TTC activity, a normal merging or shifting taper should be used.

===616.3.8.5 Downstream (Closing) Tapers===

'''Support.''' A downstream (closing) taper might be useful in termination areas to provide a visual cue to the driver that access is available back into the original lane or path that was closed.

'''Guidance.''' If used, a downstream(closing) taper should have an approximate length of 100 ft. with devices placed at a spacing of approximately 20 feet.

===616.3.8.6 One-lane, Two-way Tapers===

'''Support.''' The one-lane, two-way taper is used in advance of an activity area that occupies part of a two-way roadway in such a way that a portion of the road is used alternately by traffic in each direction.

'''Guidance.''' Traffic should be controlled by a flagger or temporary traffic control signal (if sight distance is limited), or a STOP or YIELD sign.  A short taper having an approximate length of 100 ft. with channelizing devices at approximately 20 ft. spacing should be used to guide traffic into the one-lane section, and a downstream taper should be used to guide traffic back into their original lane.  For long-term operations, centerline markings are removed and temporary edgeline markings provided to guide drivers through the tapers and the work area.

'''Support.''' An example of a one-lane, two-way traffic taper is shown in Fig. 616.3.8.

[[image:616.3.8.jpg|center|590px|thumb|<center>'''Fig. 616.3.8, Example of a One-Lane, Two Way Traffic Taper (MUTCD Fig. 6C-3)'''</center>]]

===616.3.8.7 Two-way Center Turn Lane Tapers===

'''Support.''' A taper length of 1/2 (T2) is used to close a center turn lane. Where space is limited, a shorter taper may be used.
 
==616.3.9 Detours and Diversions (MUTCD 6C.09)==

'''Support.''' A detour is a temporary rerouting of road users onto an existing highway in order to avoid a TTC zone.

'''Guidance.''' Detours should be clearly signed over their entire length so that road users can easily use existing highways to return to the original highway.

'''Support.''' A diversion is a temporary rerouting of road users onto a temporary highway or alignment placed around the work area.

Any proposed detour route must be evaluated to determine the condition of the pavement, capacity of the roadway and geometrics. Sometimes existing city streets and county roads can be improved for use as detours. If other agencies’ facilities are used, an agreement with the agency having jurisdiction over the roadway will be required. Outer roadways may be constructed early in the project phasing or enhanced to serve as detours. Refer to detour signing details (see [[616.8 Typical Applications (MUTCD 6H)#616.8.1 Listing of Typical Applications|Fig. 616.8.8 - MT]] and [[616.8 Typical Applications (MUTCD 6H)#616.8.1 Listing of Typical Applications|Fig. 616.8.9 - MT]]).

Based on engineering judgment, it is permissible for projects located on routes with less than 400 AADT to not require detours.  [http://epg.modot.org/index.php?title=616.14_Work_Zone_Safety_and_Mobility_Policy#616.14.3.2.2_Community_Relations.27_Managers_and.2For_Customer_Service_Representatives EPG 616.14.3.2.2 Community Relations’ Managers and/or Customer Service Representatives], [http://epg.modot.org/index.php?title=616.14_Work_Zone_Safety_and_Mobility_Policy#616.14.10_Transportation_Management_Plan EPG 616.14.10 Transportation Management Plan] and [http://epg.modot.org/index.php?title=616.14_Work_Zone_Safety_and_Mobility_Policy#616.14.11_General_Public_Information EPG 616.14.11 General Public Information] provide guidance for public information.

==616.3.10 One-Lane, Two-Way Traffic Control (MUTCD 6C.10)==

'''Standard.''' When traffic in both directions must use a single lane for a limited distance, movements from each end shall be coordinated.

'''Guidance.''' Provisions should be made for alternate one-way movement through the constricted section via methods such as flagger control, a flag transfer, a pilot car, traffic control signals, or stop or yield control.

Control points at each end should be chosen to permit easy passing of opposing lanes of vehicles.

If traffic on the affected one-lane roadway is not visible from one end to the other, then flagging procedures, a pilot car with a flagger used as described in [[#616.3.13 Pilot Car Method of One-Lane, Two-Way Traffic Control (MUTCD 6C.13)|EPG 616.3.13]], or a traffic control signal should be used to control opposing traffic flows.

Temporary one-lane, two-way operations are to be considered on a case-by-case basis. One-lane, two-way operations are avoided when hourly volumes exceed 600 vehicles per hour. When hourly volumes exceed 600 vehicles or conditions in the following articles cannot be met, the core team should consider alternative construction methods, such as night work, shoulder improvements for maintaining two-way traffic, time restrictions for lane closures, construction during off-peak hours, detours, diversions, etc. 

Flaggers with pilot vehicles, [[616.5 Flagger Control (MUTCD Chapter 6E)#616.5.4 Automated Flagger Assistance Devices (MUTCD 6E.04)|automated flagger assistance devices]] (AFADs) with operator, portable signal flagger device (PSFD) or [[616.6 Temporary Traffic Control Zone Devices (MUTCD 6F)#616.6.84 Temporary Traffic Control Signals (MUTCD 6F.84)|work zone traffic signals]] can all be used with one-lane, two-way operations. 

No direct payment will be made for flagger control, AFADs, PSFDs or pilot vehicles. Signs and other traffic control devices shown in [[media:616.2.6 One-Lane Two-way Operation Apr 2011a.pdf|Figure 616.2.6]], [[616.8 Typical Applications (MUTCD 6H)#616.8.1 Listing of Typical Applications|Fig. 616.8.10a - MT]] and [[616.8 Typical Applications (MUTCD 6H)#616.8.1 Listing of Typical Applications|Fig. 616.8.10c - MT]] will be paid for in accordance with [https://www.modot.org/missouri-standard-specifications-highway-construction Sec 616].

===616.3.10.1 Side Roads within the Work Area for One-Lane, Two-Way Operations===

'''Standard.'''  For projects where one-lane, two-way traffic operations are included in the traffic control plans, the core team should discuss the type of signing and access control required for each side road so the proper level of safety for both drivers and workers in the work zone is provided. See [https://epg.modot.org/files/2/25/616.8.10g_MT_2019.pdf Typical Application 616.8.10g - MT].  

'''Support.'''  Side roads are more than just the intersecting state routes.  They can be any access point to the work area.  The core team should discuss the proper signing and traffic control for all types of access points including state routes, city streets, county roads, private entrances, etc. within the work area.

The type of side road, traffic volume, duration and length of the work area and availability of alternate access or detours are all considerations that will influence the signing and access control at each side road.

'''Guidance.'''  Consideration should be given to placing a flagger and appropriate advanced signing at each intersecting side road within the limits of the active work area.  

Flaggers and  advanced signing will likely be required at high-volume access points such as state routes, major city streets and county roads, shopping or recreational centers, residential neighborhoods, campgrounds, or other high volume generators.

Alternate access or detours for the side road traffic during the active construction period should be given adequate consideration.  Length of the detour and availability of alternate routes must be considered when evaluating this option. Closing the side road and detouring the side road traffic may allow the traffic to be diverted to another side road that will be controlled by a flagger.   

'''Option.'''  Low volume, dead end roads or private access points within the work area may be evaluated on a location-by-location basis and may allow for a different method of controlling the traffic.

Individual residences along the highway within the work area can be personally contacted and informed of the process for entering and exiting their property.  The core team should determine the extent of drivers affected by the work and determine whether additional measures should be included in the traffic control plan.

==616.3.11 Flagger Method of One-Lane, Two-Way Traffic Control (MUTCD 6C.11)==
[[image:616.13.2.1.jpg|right|400px]]

'''Guidance.''' Except as provided in the below option, traffic should be controlled by a flagger at each end of a constricted section of roadway.  One of the flaggers should be designated as the coordinator.  To provide coordination of the control of the traffic, the flaggers should be able to communicate with each other orally, electronically, or with manual signals.  These manual signals should not be mistaken for flagging signals.

'''Option.''' When a one-lane, two-way TTC zone is short enough to allow a flagger to see from one end of the zone to the other, traffic may be controlled by either a single flagger or by a flagger at each end of the section.

'''Guidance.''' When a single flagger is used, the flagger should be stationed on the shoulder opposite the constriction or work space, or in a position where good visibility and traffic control can be maintained at all times.  When good visibility and traffic control cannot be maintained by one flagger station, traffic should be controlled by a flagger at each end of the section.

Flagger control is used to control traffic when two-lane, two-way operations will be restored during non-working hours. Generally, flagger segments are not longer than 3 miles for rural highways and 1 mile for urban. The maximum length is specified on the TCP so the contractor can properly stage the work. For moving operations, such as resurfacing, a third set of signs as described in Signing for One-Lane, Two-Way Resurfacing Operations is also provided.
[[image:616.13.2.2.jpg|right|400px|thumb|<center>'''Automated Flagger Assistance Device'''</center>]]

Automated Flagger Assistance Devices (AFAD) are optional portable traffic control systems that may be used by the contractor to assist flagging operations for short-term lane closures on two-lane highways. In a typical flagging operation, AFADs may be used to replace one or both flaggers. A flagger shall operate one or both AFADs by a radio control unit. If the flagger controls both AFADs on either side of the work zone, the flagger may be located away from the roadway. The primary benefit of the AFAD is the safety enhancement to the flaggers. Refer to [[media:616.2.6 One-Lane Two-way Operation Apr 2011a.pdf|Fig. 616.2.6]], [https://epg.modot.org/files/e/ea/616.8.10b_MT.pdf Fig. 616.8.10b - MT] and [https://epg.modot.org/files/7/7d/616.8.10c_MT.pdf Fig. 616.8.10c -MT].

There are two types of AFADs: 

:1. An AFAD (see [[616.5 Flagger Control (MUTCD Chapter 6E)#616.5.5 STOP/SLOW Automated Flagger Assistance Devices (MUTCD 6E.05)|EPG 616.5.5]]) that uses a remotely controlled STOP/SLOW sign on either a trailer or a movable cart system to alternately control right-of-way. 

:2. An AFAD (see [[616.5 Flagger Control (MUTCD Chapter 6E)#616.5.6 Red/Yellow Lens Automated Flagger Assistance Devices (MUTCD 6E.06)|EPG 616.5.6]]) that uses remotely controlled red and yellow lenses and a gate arm to alternately control right-of-way. 

AFADs might be appropriate for short-term and intermediate term activities. Typical applications include Temporary Traffic Control (TTC) activities such as, but not limited to: 

:1. Bridge maintenance, 

:2. Haul road crossings and 

:3. Pavement patching.

==616.3.12 Flag Transfer Method of One-Lane, Two-Way Traffic Control (MUTCD 6C.12)==

'''Support.''' The driver of the last vehicle proceeding into the one-lane section is given a red flag (or some other token) and instructed to deliver it to the flagger at the other end.  The opposite flagger, upon receipt of the flag, then knows that traffic can be permitted to move in the other direction.  A variation of this method is to replace the use of a flag with an official pilot car that follows the last road user vehicle proceeding through the section.

'''Guidance.''' The flag transfer method should be employed only where the one-way traffic is confined to a relatively short length of a road, usually no more than 1 mile long.

==616.3.13 Pilot Car Method of One-Lane, Two-Way Traffic Control (MUTCD 6C.13)==

'''Option.''' A pilot car may be used to guide a queue of vehicles through the TTC zone or detour.

'''Guidance.''' The pilot car should have the name of the contractor or contracting authority prominently displayed.

'''Standard.''' The PILOT CAR FOLLOW ME (G20-4) sign (see [[616.6 Temporary Traffic Control Zone Devices (MUTCD 6F)#616.6.58 PILOT CAR FOLLOW ME (GO20-4) and PILOT CAR IN USE WAIT & FOLLOW (GO20-4a) (MUTCD 6F.58)|EPG 616.6.58]]) shall be mounted on the rear of the pilot vehicle.

A flagger shall be stationed on the approach to the activity area to control vehicular traffic until the pilot vehicle is available.

Pilot vehicles may be specified to supplement flaggers when the length of the one-lane, two-way operation exceeds one-half mile. In addition to the flagger sign series, a vehicle mounted G20-4 “Pilot Car Follow Me” sign and PILOT CAR IN USE WAIT & FOLLOW (GO20-4a) sign shall be used in pilot vehicle operations. The access control and signing for each side road located within the work area of the one-lane, two-way operation should be determined  as discussed in [[#616.3.10.1 Side Roads within the Work Area for One-Lane, Two-Way Operations|EPG 616.3.10.1]]. Where applicable, the signing sequence for the side road should be supplemented with the PILOT CAR IN USE WAIT & FOLLOW (GO20-4a) sign. Refer to [https://epg.modot.org/files/2/25/616.8.10g_MT_2019.pdf Fig. 616.8.10g - MT], [https://epg.modot.org/index.php/616.8_Typical_Applications_(MUTCD_6H)#616.8.1_Listing_of_Typical_Applications Fig. 616.8.10 - MT].

When a pilot vehicle is used, traffic delays should be limited to 15 minutes. If the wait is longer, inform your supervisor and an additional pilot vehicle may be used to keep the delay time within the 15-minute limit.

==616.3.14 Temporary Traffic Control Signal Method of One-Lane, Two-Way Traffic Control (MUTCD 6C.14)==

'''Option.''' Traffic control signals may be used to control vehicular traffic movements in one-lane, two-way TTC zones (see [[616.8 Typical Applications (MUTCD 6H)#616.8.1 Listing of Typical Applications|Fig. 616.8.12 - MT]] and [[:Category:902 Signals|EPG 902 Signals]]).

Portable Signal Flagger Device (PSFD) Control. PSFDs are optional portable traffic control systems that may be used by the contractor to replace flagging operations for short-term lane closures on two-lane highways. In a typical flagging operation, a PSFD system requires four units with two units placed on either side of the roadway, in each direction. The primary benefit of the PSFD is the safety enhancement to the flaggers. Refer to [[616.6 Temporary Traffic Control Zone Devices (MUTCD 6F)#616.6.17.1 Signing for One-Lane, Two-Way Resurfacing Operations|EPG 616.6.17.1]] or [[616.8 Typical Applications (MUTCD 6H)#616.8.1 Listing of Typical Applications|Fig. 616.8.10c - MT]].

[[image:616.13.2.3.jpg|center|700px|thumb|<Center>'''Portable Signal Flagger Devices'''</center>]]

==616.3.15 Stop or Yield Control Method of One-Lane, Two-Way Traffic Control (MUTCD 6C.15)==

'''Option.''' STOP or YIELD signs may be used to control traffic on low-volume roads at a one-lane, two-way TTC zone when drivers are able to see the other end of the one-lane, two-way operation and having sufficient visibility of approaching vehicles.

'''Guidance.''' If the STOP or YIELD sign is installed for only one direction, then the STOP or YIELD sign should face road users who are driving on the side of the roadway that is closed for the work activity area (see [[616.8 Typical Applications (MUTCD 6H)#616.8.1 Listing of Typical Applications|Fig. 616.8.11 - MT]]).

==616.3.16 Temporary Two-Lane, Two-Way Operations==

'''Support.''' A temporary two-lane, two-way operation (head-to-head traffic) on one side of a normally divided highway is generally limited to rural locations. When head-to-head traffic is being considered, Design is contacted for concurrence. This type of traffic management may be used only after the following criteria are addressed and documented:
 
:* The benefit/cost of the two-lane, two-way operation compares favorably to the benefit/cost of other potential traffic control options (e.g., alternate routes, temporary lanes, construction staging, use of shoulders, etc.). The analysis is to include both construction and road user costs associated with each option. 

:* A capacity analysis of the two-lane, two-way operation confirms this type of traffic management can reasonably accommodate the traffic volumes without detrimental delay to travelers. 

:* The median shoulder width must be adequate for emergency stopping. 

When a two-lane, two-way operation is used, the TCP must include provisions for separating opposing traffic throughout the length of the operation with temporary concrete traffic barrier or channelizing devices and temporary pavement marking as shown on [https://www.modot.org/media/16894 Standard Plans 617.20], [https://www.modot.org/media/16892 616.10] and [https://www.modot.org/media/16897 620.10], respectively, except when the two-lane, two-way operation is located on an urban travelway and the posted speed limit prior to construction is less than 45 mph. The speed limit for head-to-head traffic is based on [[616.12 Work Zone Speed Limits|EPG 616.12 Work Zone Speed Limits]]. At these locations, all obstructions or fixed objects shall have protection provided for both directions of travel. This may require providing temporary installations of impact attenuators or crash cushions for guardrail, bridge ends, barrier walls, etc. on what would normally be the downstream side of the obstruction. 

Crossovers constructed to facilitate two-lane, two-way operation are designed for speeds not less than 10 mph below the posted speed limit prior to construction, unless unusual site conditions exist. Crossovers are located where horizontal and vertical alignments provide sufficient sight distance. 

For payment, the components (aggregate, asphalt, drainage, grading, etc.) of each crossover are calculated and the quantities added into the plans. 

[[image:616.1.3.4.jpg|center|900px]]

[[Category:616 Temporary Traffic Control|616.03]]