902.18 Flashing Beacons (MUTCD Chapter 4S): Difference between revisions

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==902.12.1  General Design and Operation of Flashing Beacons (MUTCD Section 4L.01)==
[[Category:902 Signals (MUTCD Part 4)|902.18]]


'''Support.''' A Flashing Beacon is a highway traffic signal with one or more signal sections that operates in a flashing mode. It can provide traffic control when used as an intersection control beacon (see EPG 902.12.2) or it can provide warning when used in other applications (see EPG 902.12.3 through EPG 902.12.5).
=={{SpanID|902.18.1}}902.18.1  General Design and Operation of Flashing Beacons (MUTCD Section 4S.01)==


When used with good judgment, the installation of a flashing beacon can be an extremely effective traffic control device. However, indiscriminate use degrades their effectiveness and affects the usefulness of other flasher installations. Flashing beacons can be installed by MoDOT or by outside parties. An engineering study is to be performed to determine the need for them.
'''Support. '''A flashing beacon is a highway traffic signal with one or more signal sections that operates in a flashing mode. It can provide traffic control when used as an Intersection Control Beacon (see [[902.18 Flashing Beacons (MUTCD Chapter 4S) #902.18.2|EPG 902.18.2]]) or it can provide warning when used in other applications (see [[902.18 Flashing Beacons (MUTCD Chapter 4S) #902.18.3|EPG 902.18.3]], [[902.18 Flashing Beacons (MUTCD Chapter 4S) #902.18.4|902.18.4]], and [[902.18 Flashing Beacons (MUTCD Chapter 4S) #902.18.5|902.18.5]]).


Flashing beacons can be used in a number of different applications. The installation of flashing beacons at any location on the State Highway System is to be approved by the District Traffic Engineer or designee. Likewise, the removal of any flashing beacons installed by MoDOT over any roadway shall also have prior approval from the District Traffic Engineer or designee.
A flashing beacon can be installed by MoDOT or by outside parties. An engineering study is to be performed to determine the need for them.  


A number of flashing beacons present on state highways were installed and are operated by others. No concerted attempt to have them removed is to be engaged in except when such a flasher is considered a potential safety problem to the motoring public, or conditions have changed so a flasher is no longer needed. If these conditions occur, the organization operating the flasher is to be encouraged to remove it.  
The removal or installation of a flashing beacon on the State Highway System requires approval of the District Traffic Engineer or designee.


'''Standard.''' Flashing Beacon units and their mountings shall comply with the provisions of [[902.5 Traffic Control Signal Features (MUTCD Chapter 4D)|EPG 902.5]], except as otherwise provided in this article.
'''Standard. '''Flashing beacon units, their mountings, signal visors, and backplates shall comply with the provisions of [[902.4_Design_Features_of_Traffic_Control_Signals_(MUTCD_Chapter_4D)|EPG 902.4]] and [[902.5 Traffic Control Signal Indications (MUTCD Chapter 4E) #902.5 | 902.5]] except as otherwise provided in this Article.


Beacons shall be flashed at a rate of not less than 50 or more than 60 times per minute. The illuminated period of each flash shall be a minimum of 1/2 and a maximum of 2/3 of the total cycle.
Beacons shall be flashed at a rate of not less than 50 or more than 60 times per minute. The illuminated period of each flash shall be a minimum of ½ and a maximum of ⅔ of the total cycle.


A beacon shall not be included within the border of a sign except for SCHOOL SPEED LIMIT sign beacons (see EPG 902.12.4 and MUTCD Section 7B.15).
A beacon shall not be included within the border of a sign except for Interchange Exit Direction signs with advisory speed panels (see [[903.5 Guide Signs - Freeways and Expressways (MUTCD Chapter 2E) #903.5.25|EPG 903.5.25]]).  


'''Guidance.''' If used to supplement a warning or regulatory sign, the edge of the beacon signal housing should normally be located no closer than 12 in. outside of the nearest edge of the sign.
All flashing beacon signal indications shall be 12 inches in diameter.  


'''Option.''' An automatic dimming device may be used to reduce the brilliance of flashing yellow signal indications during night operation.
'''Guidance. '''If used to supplement a warning or regulatory sign, the edge of the beacon signal housing should normally be located no closer than 12 inches outside of the nearest edge of the sign or from the nearest edge of any of the signs and plaques in a sign assembly.


==902.12.2  Intersection Control Beacon (MUTCD Section 4L.02)==
'''Option. '''An automatic dimming device may be used to reduce the brilliance of flashing yellow signal indications during night operation.


'''Standard.''' An Intersection Control Beacon shall consist of one or more signal faces directed toward each approach to an intersection. Each signal face shall consist of one or more signal sections of a standard traffic signal face, with flashing CIRCULAR YELLOW or CIRCULAR RED signal indications in each signal face. They shall be installed and used only at an intersection to control two or more directions of travel.
Backplates (see [[902.4_Design_Features_of_Traffic_Control_Signals_(MUTCD_Chapter_4D)#902.4.6_Visibility,_Aiming,_and_Shielding_of_Signal_Faces_(MUTCD_Section_4D.06)|EPG 902.4.6]]) may be used with flashing beacons.
 
=={{SpanID|902.18.2}}902.18.2  Intersection Control Beacon (MUTCD Section 4S.02)==
 
'''Standard. '''An Intersection Control Beacon shall consist of one or more signal faces directed toward each approach to an intersection. Each signal face shall consist of one or more signal sections of a standard traffic signal face, with flashing CIRCULAR YELLOW or CIRCULAR RED signal indications in each signal face. They shall be installed and used only at an intersection to control two or more directions of travel.


Application of Intersection Control Beacon signal indications shall be limited to the following:
Application of Intersection Control Beacon signal indications shall be limited to the following:
::A. Yellow on one route (normally the major street) and red for the remaining approaches that are controlled by STOP signs, or
::B. Red for all approaches (if all of the intersection approaches are controlled by STOP signs).


:A. Yellow on one route (normally the major street) and red for the remaining approaches, and
Flashing yellow signal indications shall not face conflicting vehicular approaches.


:B. Red for all approaches (if the warrant described in [[903.5 Regulatory Signs#903.5.4.3 Multiway Stop Applications (MUTCD Section 2B.07)|EPG 903.5.4.3]] for a multi-way stop is satisfied).
A STOP sign (see  [[903.2 Regulatory Signs and Barricades (MUTCD Chapter 2B) #903.2.4|EPG 903.2.4]]) shall be used on approaches to which a flashing red signal indication is displayed on an Intersection Control Beacon.


Flashing yellow signal indications shall not face conflicting vehicular approaches.
If two horizontally-aligned red signal indications are used on an approach for an Intersection Control Beacon, they shall be flashed simultaneously to avoid being confused with grade crossing flashing-light signals. If two vertically-aligned red signal indications that have a physical separation between them are used on an approach for an Intersection Control Beacon, they shall be flashed alternately.


A STOP sign shall be used on approaches to which a flashing red signal indication is displayed on an Intersection Control Beacon (see MUTCD Section 2B.04).
Twelve-inch signal indications shall be used for Intersection Control.


If two horizontally aligned red signal indications are used on an approach for an Intersection Control Beacon, they shall be flashed simultaneously to avoid being confused with grade crossing flashing-light signals.  If two vertically aligned red signal indications are used on an approach for an Intersection Control Beacon, they shall be flashed alternately.
When an overhead beacon is authorized for installation at an intersection, the support pole shall be placed in accordance with the AASHTO Roadside Design Guide clear zone guidelines.


All intersection control beacons shall be installed and/or maintained to provide a clearance over the roadway of 16 ft. to 19 feet.  
All intersection control beacons shall be installed and/or maintained to provide a minimum clearance of 16 feet and a maximum clearance of 19 feet above the pavement grade.


A pole on state right of way owned by others shall not be used to support a span wire flasher. If an adjustment of the location for a department installed pole cannot be made, the existing pole shall be moved at the expense of the owner.
A pole on state right of way owned by others shall not be used to support a span wire flasher. If an adjustment of the location for a department installed pole cannot be made, the existing pole shall be moved at the expense of the owner.


Hybrid beacons (pedestrian and emergency) are not considered an intersection control beacon and are not subject to provisions stated in the section.  Refer to [[902.6 Pedestrian Control Features (MUTCD Chapter 4E)|EPG 902.6]] and [[902.7 Pedestrian Hybrid Beacons (MUTCD Chapter 4F)|EPG 902.7]] for provisions for pedestrian and emergency hybrid beacons, respectively.
'''Support. '''Hybrid beacons (pedestrian and emergency) are not considered intersection control beacons and are not subject to provisions stated in the section.


'''Guidance.''' An Intersection Control Beacon should not be mounted on a pedestal in the roadway unless the pedestal is within the confines of a traffic or pedestrian island.
Provisions for pedestrian hybrid beacons are described in [[902.10 Pedestrian Hybrid Beacons (MUTCD Chapter 4J) #902.10|EPG 902.10]].


'''Option.''' Where there are two or more approach lanes, it is desirable to center a head over each lane; however, one head per approach is acceptable.
Provisions for emergency hybrid beacons are described in [[902.14 Hybrid Beacons for Emergency-Vehicle Access (MUTCD Chapter 4N) #902.14|EPG 902.14]].


'''Guidance.''' Conditions for which intersection beacons should be considered are:  
'''Guidance. '''An intersection control beacon should be considered at intersections when any of the following conditions apply:


:* A required stop after a long period of uninterrupted speed,  
:A. A required stop after a long period of uninterrupted speed,


:* A required stop on a long tangent section of roadway where cross-street traffic may have trouble judging the distance and speed of an oncoming vehicle,  
:B. A required stop on a long tangent section of roadway where cross-street traffic may have trouble judging the distance and speed of an oncoming vehicle,


:* A stop condition not readily visible to the approaching driver,  
:C. A stop condition not readily visible to the approaching driver,


:* A situation where traffic on the major roadway may not be aware of cross-street traffic.  
:D. A situation where traffic on the major roadway may not be aware of cross-street traffic.


'''Standard.''' When an overhead flasher is authorized for installation at an intersection, the support pole shall be placed in accordance with the AASHTO ''Roadside Design Guide'' clear zone guidelines.
An Intersection Control Beacon should not be mounted on a pedestal in the roadway unless the pedestal is within the confines of a traffic or pedestrian island.
[[image:902.12.2.jpg|center|500px|thumb|<center>'''Typical Flasher Layouts'''</center>]]


'''Option.''' Supplemental signal indications may be used on one or more approaches in order to provide adequate visibility to approaching road users.
'''Option. '''Supplemental signal indications may be used on one or more approaches in order to provide adequate visibility to approaching road users.


Intersection Control Beacons may be used at intersections where traffic or physical conditions do not justify conventional traffic control signals but crash rates indicate the possibility of a special need.
Intersection Control Beacons may be used at intersections where traffic or physical conditions do not justify conventional traffic control signals but crash rates indicate the possibility of a special need.


An Intersection Control Beacon is generally located over the center of an intersection; however, it may be used at other suitable locations.
An Intersection Control Beacon is generally located over the center of an intersection; however, it may be used at other suitable locations.


==902.12.3 Warning Beacon (MUTCD Section 4L.03)==
{{SpanID|fig902.18.2}}
 
[[File:Figure 902.18.2 Typical Intersection Control Beacon Configuration.png|alt="Two intersection diagrams are shown side-by-side, illustrating typical flasher layouts. Each diagram uses black circles to represent flasher signal locations and black triangular arrows to represent the direction of travel and turning movements.
'''Support.''' Typical applications of Warning Beacons include the following:
On the left diagram, a diagonal series of arrows and flasher locations indicating left-turn (center lane), through, and right-turn movements.
 
On the right diagram, a similar diagonal flasher line runs from the lower left to the upper right, with flasher locations and arrows including a left-turn arrow in the center lane."
:*A. At obstructions in or immediately adjacent to the roadway;
|thumb|center|1000px|'''Figure 902.18.2''' Typical Intersection Control Beacon Configuration]]
 
:*B. As supplemental emphasis to warning signs;


:*C. As emphasis for midblock crosswalks;
=={{SpanID|902.18.3}}902.18.3  Warning Beacon (MUTCD Section 4S.03)==


:*D. As supplemental emphasis to regulatory signs, except STOP, DO NOT ENTER, WRONG WAY and SPEED LIMIT signs (see EPG 902.12.4 Speed Limit Sign Beacons) ; and
'''Support. '''Typical applications of Warning Beacons include the following:
:A. As supplemental emphasis to signs or object markers on or in front of obstructions that are in or immediately adjacent to the roadway;
:B. As supplemental emphasis to warning signs;
:C. As emphasis for midblock crosswalks;
:D. As supplemental emphasis to regulatory signs, except STOP, DO NOT ENTER, WRONG WAY, and SPEED LIMIT signs; and
:E. In conjunction with a regulatory sign that includes the phrase WHEN FLASHING in its legend to indicate that the regulation is in effect or that the condition is present only at certain times. [[903.1 General (MUTCD Chapter 2A) #903.1.12|EPG 903.1.12]] prohibits the use of flashing light-emitting diode (LED) units within the legend or border of the sign in conjunction with the phrase WHEN FLASHING in its legend.


:*E. In conjunction with a regulatory or warning sign that includes the phrase WHEN FLASHING in its legend to indicate that the regulation is in effect or that the condition is present only at certain times.
'''Standard. '''A Warning Beacon shall consist of one or more signal sections of a standard traffic signal face with a flashing CIRCULAR YELLOW signal indication in each signal section.  


'''Standard.''' A Warning Beacon shall consist of one or more signal sections of a standard traffic signal face with a flashing CIRCULAR YELLOW signal indication in each signal section.
A Warning Beacon shall be used only to supplement an appropriate warning or regulatory sign or marker.
A Warning Beacon shall be used only to supplement an appropriate warning or regulatory sign or marker.  


Warning Beacons, if used at intersections, shall not face conflicting vehicular approaches.
Warning Beacons, if used at intersections, shall not face conflicting vehicular approaches.


If a Warning Beacon is suspended over the roadway, the clearance above the pavement shall be a minimum of 16 ft. and a maximum of 19 feet.
'''Guidance. '''The condition or regulation justifying Warning Beacons should largely govern their location with respect to the roadway.
 
'''Guidance.''' The condition or regulation justifying Warning Beacons should largely govern their location with respect to the roadway.


If an obstruction is in or adjacent to the roadway, illumination of the lower portion or the beginning of the obstruction or a sign on or in front of the obstruction, in addition to the beacon, should be considered.
If an obstruction is in or adjacent to the roadway, illumination of the lower portion or the beginning of the obstruction or illumination of the sign on or in front of the obstruction, in addition to the beacon, should be considered.


Warning Beacons should be operated only during those periods or times when the condition or regulation exists.
Warning Beacons should be operated only during those periods or times when the condition or regulation exists.


'''Option.''' Warning Beacons that are actuated by pedestrians, bicyclists, or other road users may be used as appropriate to provide additional warning to vehicles approaching a crossing or other location.
'''Option. '''If Warning Beacons have more than one signal section, they may be flashed either alternately or simultaneously.
 
If Warning Beacons have more than one signal section, they may be flashed either alternately or simultaneously.
 
A flashing yellow beacon interconnected with a traffic signal controller assembly may be used with a traffic signal warning sign (see MUTCD Section 2C.36).
 
Warning beacons may be installed in conjunction with school advance signing or in conjunction with a school speed limit assembly at the request of the school district and at their cost.
 
Warning beacons may be installed in conjunction with emergency vehicle advance signing at the request of the emergency vehicle service district and at their cost.  


'''Standard.''' School warning beacons only operate when there is activity at the school or school crossing. When school speed limit signing is installed, beacons shall be installed with the school speed limit signing. The beacons are only activated at times when the school speed limit applies.  
Warning Beacons that are actuated by pedestrians, bicyclists, or other road users may be used as appropriate to provide additional warning to vehicles approaching a crossing or other location.


Emergency vehicle warning beacons are set up to operate only when emergency vehicles are exiting the station or garage on a duly authorized emergency run. As with the school beacons, these beacons enhance the meaning of the advanced signing by only flashing when emergency activity is occurring.  
'''Guidance. '''An audible information device should be used with pedestrian-actuated Warning Beacons to assist pedestrians with vision disabilities.


See [[#902.12.7 Procedures For Advance Beacon Installations by Outside Parties|EPG 902.12.7 Procedures For Advance Beacon Installations by Outside Parties]] for additional information regarding school and emergency vehicle warning beacons.
'''Standard. '''If an audible information device is used in conjunction with a pedestrian-actuated Warning Beacon at a pedestrian crossing, the audible information device shall not use vibrotactile indications or percussive indications. The audible information device shall include a speech message that says, “Warning lights are flashing.” The audible message shall be spoken twice.


==902.12.4  Speed Limit Sign Beacon (MUTCD Section 4L.04)==
'''Option. '''Warning Beacons may be installed in conjunction with School Zone signing (See [[908.2 Signs (MUTCD Chapter 7B) #908.12.2|EPG 908.2.2]]) at the request of the school district and at their cost.


'''Standard.''' A Speed Limit Sign Beacon shall be used only to supplement a Speed Limit sign.
Warning Beacons may be installed in conjunction with Emergency Vehicle (W11-8) signs (See [[903.3 Warning Signs and Object Markers (MUTCD Chapter 2C)#903.3.44|903.3.44]]) at the request of the emergency vehicle service district and at their cost.


A Speed Limit Sign Beacon shall consist of one or more signal sections of a standard traffic control signal face, with a flashing CIRCULAR YELLOW signal indication in each signal section.  The signal indications shall have a nominal diameter of not less than 12 inches.  If two signal indications are used, they shall be vertically aligned.  If two signal indications are used, they shall be alternately flashed.
'''Standard. '''Warning Beacons installed in conjunction with school zone signing shall only operate when there is activity at the school.


If used, the phrase WHEN FLASHING is required to be in the legend or on a supplemental plaque.
'''Support. '''Emergency vehicle Warning Beacons are set up to operate only when emergency vehicles are exiting the station or garage on a duly authorized emergency run. These Warning Beacons enhance the meaning of the advanced signing by only flashing when emergency activity is occurring.


'''Option.''' A Speed Limit Sign Beacon may be included within the border of a School Speed Limit (S5-1) sign (see MUTCD Section 7B.15).
=={{SpanID|902.18.4}}902.18.4  Speed Limit Sign Beacon (MUTCD Section 4S.04)==


==902.12.5  Stop Beacon (MUTCD Section 4L.05)==
'''Standard. '''A Speed Limit Sign Beacon shall be used only to supplement a Speed Limit sign.


'''Standard.''' A Stop Beacon shall be used only to supplement a STOP sign, a DO NOT ENTER sign, or a WRONG WAY sign.
A Speed Limit Sign Beacon shall consist of one or more signal sections of a standard traffic control signal face, with a flashing CIRCULAR YELLOW signal indication in each signal section. The signal indications shall have a nominal diameter of not less than 12 inches. If two signal indications are used, they shall be vertically aligned. If two signal indications are used, they shall be alternately flashed.


A Stop Beacon shall consist of one or more signal sections of a standard traffic signal face with a flashing CIRCULAR RED signal indication in each signal section. If two horizontally aligned signal indications are used for a Stop Beacon, they shall be flashed simultaneously to avoid being confused with grade crossing flashing-light signals.  If two vertically aligned signal indications on the same structure are used for a Stop Beacon, they shall be flashed alternately.
'''Option. '''A Speed Limit Sign Beacon may be used with a fixed or variable Speed Limit sign. If applicable, a flashing Speed Limit Sign Beacon (with an appropriate accompanying sign) may be used to indicate that the displayed speed limit is in effect.


If mounted above a STOP sign, a DO NOT ENTER sign, or a WRONG WAY sign the bottom of the signal housing of a Stop Beacon shall be not less than 12 in. or more than 24 in. above the top of the sign. If mounted below a STOP sign, a DO NOT ENTER sign, or a WRONG WAY sign the top of the signal housing of a Stop Beacon shall be not less than 12 in. or more than 24 in. (only used when an additional sign is used below, i.e. Divided Highway, All Way, etc.) below the bottom of the sign.
Speed Limit Sign beacons may be installed in conjunction with School Speed Limit signing (See [[908.2 Signs (MUTCD Chapter 7B) #908.2.5| EPG 908.2.5]]) at the request of the school district and at their cost.


==902.12.6 Interactive Flashing Beacons ==
'''Standard. '''When School Speed Limit signing (See [[908.2 Signs (MUTCD Chapter 7B) #908.2.5| EPG 908.2.5]]) is installed, Speed Limit Sign Beacons shall be installed in conjunction with the School Speed Limit Signing.'''


'''Option.''' Types of interactive flashing beacons may be any of the previously mentioned types of beacons.  These beacons may be accompanied with signs that reinforce the message. Examples include: beacons activated by approaching traffic or excessive speed, beacons used to give advance warning of a yellow change interval at a signalized intersection or beacons used to notify motorists of traffic stopped ahead. Beacons activated by approaching traffic may be used where sight distance is limited and cross-street traffic may have trouble judging the distance and speed of approaching traffic. Beacons activated when motorists exceed a posted speed may be used where conditions require a reduction in traffic speed. Examples of this use include low speed curves or where drivers regularly exceed the posted speed limit. Beacons activated a few seconds before (or at the start of) the yellow change interval at a signalized intersection may be used to give high speed traffic advance warning of the signal changing from green to yellow.  
Speed Limit Sign Beacons installed in conjunction with School Speed Limit signing shall only operate at times when the school speed limit applies.


'''Standard.''' Interactive flashing beacons shall be activated only when required.
=={{SpanID|902.18.5}}902.18.5  Stop Beacon (MUTCD Section 4S.05)==


==902.12.7 Procedures For Advance Beacon Installations by Outside Parties==
'''Standard. '''A Stop Beacon shall be used only to supplement a STOP sign, a DO NOT ENTER sign, or a WRONG WAY sign.


'''Standard.''' Advance beacons such as:  school warning, school speed limit, and emergency vehicle warning beacons are installed under contract.  The district will obtain appropriate signed contracts to be sent to Central Office Traffic for further handling. These contracts deal with the installation and transfer of ownership of the installation from the outside party to the Commission.  
A Stop Beacon shall consist of one or more signal sections of a standard traffic signal face with a flashing CIRCULAR RED signal indication in each signal section. If two horizontally-aligned signal indications are used for a Stop Beacon, they shall be flashed simultaneously to avoid being confused with grade crossing flashing-light signals. If two vertically-aligned signal indications are used for a Stop Beacon, they shall be flashed alternately.


'''Support.''' The following standard contracts are available:
The edge of the signal housing of a Stop Beacon shall be not less than 12 inches or more than 24 inches from the nearest edge of the STOP sign, DO NOT ENTER sign, or WRONG WAY sign that it supplements.


:* [[153.20 Traffic|TR8 - Installation of Roadside Flashers for School Operation]]
=={{SpanID|902.18.6}}902.18.6 Interactive Flashing Beacon==
:* [[153.20 Traffic|TR26 - Installation of Roadside Flashers for Emergency Vehicle Operation]]
'''Standard.''' Plans for installation shall be the responsibility of the outside party and shall conform to the latest standards of MoDOT.  


Once the contract is executed, a permit to work on MoDOT’s right-of-way shall be obtained by the outside party.   Once issued, the outside party may proceed to install the beacons. A contractor or the outside party shall complete the installation; however, a licensed electrician shall supervise the installation.  
'''Option. '''Types of interactive flashing beacons may be any of the previously mentioned types of beacons. These beacons may be accompanied with signs that reinforce the message. Examples include: beacons activated by approaching traffic or excessive speed, beacons used to give advance warning of a yellow change interval at a signalized intersection or beacons used to notify motorists of traffic stopped ahead. Beacons activated when motorists exceed a posted speed may be used where conditions require a reduction in traffic speed. Examples of this use include low speed curves or where drivers regularly exceed the posted speed limit. Beacons activated a few seconds before (or at the start of) the yellow change interval at a signalized intersection may be used to give high speed traffic advance warning of the signal changing from green to yellow.


Layouts are illustrated in [[media:902.11 Advance Flasher Figures 2012.doc|Fig. 902.11 Advanced Flasher Figures]] and equipment listed in [[media:902.11 Appendix.doc|Appendix]].
'''Standard. '''Interactive flashing beacons shall be activated only when required.


With the exception of the signs and mounting brackets supplied by MoDOT, all costs shall be the responsibility of the outside party. This includes but is not limited to installation and power.  
=={{SpanID|902.18.7}}902.18.7 Procedures for Advance Beacon Installations by Outside Parties==


Beacons shall be active only during those times when the conditions of the advanced signing are applicable or when the enhancement of the signed message is needed. The times of operation, timing, and method of operation are approved by MoDOT.  
'''Standard. '''Advance beacons such as school warning, school speed limit, and emergency vehicle warning beacons are installed under contract. The district will obtain appropriate signed contracts and will follow execution guidelines in [[153.21 Traffic #153.21|EPG 153.21]]. These contracts deal with the installation and transfer of ownership of the installation from the outside party to the Commission.


MoDOT will maintain installations and equipment unless otherwise indicated in the contract. Power costs after transfer of ownership to MoDOT and any other equipment off right of way are the responsibility of the outside party.
'''Support. '''The following standard contracts are available:
# TR8 - Installation of Roadside Flashers for School Operation
# TR26 - Installation of Roadside Flashers for Emergency Vehicle Operation


Flashing beacons shall only be installed on advanced signing and shall not be installed at the condition applicable to the advanced signing.  
'''Standard. '''Plans for installation shall be the responsibility of the outside party and shall conform to the latest standards of MoDOT.


Only one flasher shall be permitted per approach.
Once the contract is executed, a permit to work on MoDOT’s right-of-way shall be obtained by the outside party. Once issued, the outside party may proceed to install the beacons. A contractor or the outside party shall complete the installation; however, a licensed electrician shall supervise the installation. The outside party needs to coordinate with MoDOT prior to installation of the flasher to have MoDOT personnel verify hardware and equipment is acceptable for use on the state highway system. Upon completion of installation, MoDOT personnel shall verify correct installation prior to release of the permit and acceptance of the flasher.


General layouts for an intersection control beacon are illustrated in [[#fig902.18.2|Figure 902.18.2]].


All costs shall be the responsibility of the outside party. This includes but is not limited to installation and power; however, the signs and mounting brackets shall be supplied by MoDOT. All specifications shall be met to ensure the proper installation is in place.


Beacons shall be active only during those times when the conditions of the advance signing are applicable or when the enhancement of the signed message is needed. The times of operation, timing, and method of operation are approved by MoDOT.


The contract shall establish responsibility for future maintenance, power costs, programming ownership, and replacement equipment.


Flashing beacons shall only be installed on advanced signing or on school speed limit signing.


[[Category:902 Signals|902.12]]
Only one flasher assembly shall be permitted per approach.

Latest revision as of 08:50, 13 January 2026


902.18.1 General Design and Operation of Flashing Beacons (MUTCD Section 4S.01)

Support. A flashing beacon is a highway traffic signal with one or more signal sections that operates in a flashing mode. It can provide traffic control when used as an Intersection Control Beacon (see EPG 902.18.2) or it can provide warning when used in other applications (see EPG 902.18.3, 902.18.4, and 902.18.5).

A flashing beacon can be installed by MoDOT or by outside parties. An engineering study is to be performed to determine the need for them.

The removal or installation of a flashing beacon on the State Highway System requires approval of the District Traffic Engineer or designee.

Standard. Flashing beacon units, their mountings, signal visors, and backplates shall comply with the provisions of EPG 902.4 and 902.5 except as otherwise provided in this Article.

Beacons shall be flashed at a rate of not less than 50 or more than 60 times per minute. The illuminated period of each flash shall be a minimum of ½ and a maximum of ⅔ of the total cycle.

A beacon shall not be included within the border of a sign except for Interchange Exit Direction signs with advisory speed panels (see EPG 903.5.25).

All flashing beacon signal indications shall be 12 inches in diameter.

Guidance. If used to supplement a warning or regulatory sign, the edge of the beacon signal housing should normally be located no closer than 12 inches outside of the nearest edge of the sign or from the nearest edge of any of the signs and plaques in a sign assembly.

Option. An automatic dimming device may be used to reduce the brilliance of flashing yellow signal indications during night operation.

Backplates (see EPG 902.4.6) may be used with flashing beacons.

902.18.2 Intersection Control Beacon (MUTCD Section 4S.02)

Standard. An Intersection Control Beacon shall consist of one or more signal faces directed toward each approach to an intersection. Each signal face shall consist of one or more signal sections of a standard traffic signal face, with flashing CIRCULAR YELLOW or CIRCULAR RED signal indications in each signal face. They shall be installed and used only at an intersection to control two or more directions of travel.

Application of Intersection Control Beacon signal indications shall be limited to the following:

A. Yellow on one route (normally the major street) and red for the remaining approaches that are controlled by STOP signs, or
B. Red for all approaches (if all of the intersection approaches are controlled by STOP signs).

Flashing yellow signal indications shall not face conflicting vehicular approaches.

A STOP sign (see EPG 903.2.4) shall be used on approaches to which a flashing red signal indication is displayed on an Intersection Control Beacon.

If two horizontally-aligned red signal indications are used on an approach for an Intersection Control Beacon, they shall be flashed simultaneously to avoid being confused with grade crossing flashing-light signals. If two vertically-aligned red signal indications that have a physical separation between them are used on an approach for an Intersection Control Beacon, they shall be flashed alternately.

Twelve-inch signal indications shall be used for Intersection Control.

When an overhead beacon is authorized for installation at an intersection, the support pole shall be placed in accordance with the AASHTO Roadside Design Guide clear zone guidelines.

All intersection control beacons shall be installed and/or maintained to provide a minimum clearance of 16 feet and a maximum clearance of 19 feet above the pavement grade.

A pole on state right of way owned by others shall not be used to support a span wire flasher. If an adjustment of the location for a department installed pole cannot be made, the existing pole shall be moved at the expense of the owner.

Support. Hybrid beacons (pedestrian and emergency) are not considered intersection control beacons and are not subject to provisions stated in the section.

Provisions for pedestrian hybrid beacons are described in EPG 902.10.

Provisions for emergency hybrid beacons are described in EPG 902.14.

Guidance. An intersection control beacon should be considered at intersections when any of the following conditions apply:

A. A required stop after a long period of uninterrupted speed,
B. A required stop on a long tangent section of roadway where cross-street traffic may have trouble judging the distance and speed of an oncoming vehicle,
C. A stop condition not readily visible to the approaching driver,
D. A situation where traffic on the major roadway may not be aware of cross-street traffic.

An Intersection Control Beacon should not be mounted on a pedestal in the roadway unless the pedestal is within the confines of a traffic or pedestrian island.

Option. Supplemental signal indications may be used on one or more approaches in order to provide adequate visibility to approaching road users.

Intersection Control Beacons may be used at intersections where traffic or physical conditions do not justify conventional traffic control signals but crash rates indicate the possibility of a special need.

An Intersection Control Beacon is generally located over the center of an intersection; however, it may be used at other suitable locations.


Figure 902.18.2 Typical Intersection Control Beacon Configuration

902.18.3 Warning Beacon (MUTCD Section 4S.03)

Support. Typical applications of Warning Beacons include the following:

A. As supplemental emphasis to signs or object markers on or in front of obstructions that are in or immediately adjacent to the roadway;
B. As supplemental emphasis to warning signs;
C. As emphasis for midblock crosswalks;
D. As supplemental emphasis to regulatory signs, except STOP, DO NOT ENTER, WRONG WAY, and SPEED LIMIT signs; and
E. In conjunction with a regulatory sign that includes the phrase WHEN FLASHING in its legend to indicate that the regulation is in effect or that the condition is present only at certain times. EPG 903.1.12 prohibits the use of flashing light-emitting diode (LED) units within the legend or border of the sign in conjunction with the phrase WHEN FLASHING in its legend.

Standard. A Warning Beacon shall consist of one or more signal sections of a standard traffic signal face with a flashing CIRCULAR YELLOW signal indication in each signal section.

A Warning Beacon shall be used only to supplement an appropriate warning or regulatory sign or marker.

Warning Beacons, if used at intersections, shall not face conflicting vehicular approaches.

Guidance. The condition or regulation justifying Warning Beacons should largely govern their location with respect to the roadway.

If an obstruction is in or adjacent to the roadway, illumination of the lower portion or the beginning of the obstruction or illumination of the sign on or in front of the obstruction, in addition to the beacon, should be considered.

Warning Beacons should be operated only during those periods or times when the condition or regulation exists.

Option. If Warning Beacons have more than one signal section, they may be flashed either alternately or simultaneously.

Warning Beacons that are actuated by pedestrians, bicyclists, or other road users may be used as appropriate to provide additional warning to vehicles approaching a crossing or other location.

Guidance. An audible information device should be used with pedestrian-actuated Warning Beacons to assist pedestrians with vision disabilities.

Standard. If an audible information device is used in conjunction with a pedestrian-actuated Warning Beacon at a pedestrian crossing, the audible information device shall not use vibrotactile indications or percussive indications. The audible information device shall include a speech message that says, “Warning lights are flashing.” The audible message shall be spoken twice.

Option. Warning Beacons may be installed in conjunction with School Zone signing (See EPG 908.2.2) at the request of the school district and at their cost.

Warning Beacons may be installed in conjunction with Emergency Vehicle (W11-8) signs (See 903.3.44) at the request of the emergency vehicle service district and at their cost.

Standard. Warning Beacons installed in conjunction with school zone signing shall only operate when there is activity at the school.

Support. Emergency vehicle Warning Beacons are set up to operate only when emergency vehicles are exiting the station or garage on a duly authorized emergency run. These Warning Beacons enhance the meaning of the advanced signing by only flashing when emergency activity is occurring.

902.18.4 Speed Limit Sign Beacon (MUTCD Section 4S.04)

Standard. A Speed Limit Sign Beacon shall be used only to supplement a Speed Limit sign.

A Speed Limit Sign Beacon shall consist of one or more signal sections of a standard traffic control signal face, with a flashing CIRCULAR YELLOW signal indication in each signal section. The signal indications shall have a nominal diameter of not less than 12 inches. If two signal indications are used, they shall be vertically aligned. If two signal indications are used, they shall be alternately flashed.

Option. A Speed Limit Sign Beacon may be used with a fixed or variable Speed Limit sign. If applicable, a flashing Speed Limit Sign Beacon (with an appropriate accompanying sign) may be used to indicate that the displayed speed limit is in effect.

Speed Limit Sign beacons may be installed in conjunction with School Speed Limit signing (See EPG 908.2.5) at the request of the school district and at their cost.

Standard. When School Speed Limit signing (See EPG 908.2.5) is installed, Speed Limit Sign Beacons shall be installed in conjunction with the School Speed Limit Signing.

Speed Limit Sign Beacons installed in conjunction with School Speed Limit signing shall only operate at times when the school speed limit applies.

902.18.5 Stop Beacon (MUTCD Section 4S.05)

Standard. A Stop Beacon shall be used only to supplement a STOP sign, a DO NOT ENTER sign, or a WRONG WAY sign.

A Stop Beacon shall consist of one or more signal sections of a standard traffic signal face with a flashing CIRCULAR RED signal indication in each signal section. If two horizontally-aligned signal indications are used for a Stop Beacon, they shall be flashed simultaneously to avoid being confused with grade crossing flashing-light signals. If two vertically-aligned signal indications are used for a Stop Beacon, they shall be flashed alternately.

The edge of the signal housing of a Stop Beacon shall be not less than 12 inches or more than 24 inches from the nearest edge of the STOP sign, DO NOT ENTER sign, or WRONG WAY sign that it supplements.

902.18.6 Interactive Flashing Beacon

Option. Types of interactive flashing beacons may be any of the previously mentioned types of beacons. These beacons may be accompanied with signs that reinforce the message. Examples include: beacons activated by approaching traffic or excessive speed, beacons used to give advance warning of a yellow change interval at a signalized intersection or beacons used to notify motorists of traffic stopped ahead. Beacons activated when motorists exceed a posted speed may be used where conditions require a reduction in traffic speed. Examples of this use include low speed curves or where drivers regularly exceed the posted speed limit. Beacons activated a few seconds before (or at the start of) the yellow change interval at a signalized intersection may be used to give high speed traffic advance warning of the signal changing from green to yellow.

Standard. Interactive flashing beacons shall be activated only when required.

902.18.7 Procedures for Advance Beacon Installations by Outside Parties

Standard. Advance beacons such as school warning, school speed limit, and emergency vehicle warning beacons are installed under contract. The district will obtain appropriate signed contracts and will follow execution guidelines in EPG 153.21. These contracts deal with the installation and transfer of ownership of the installation from the outside party to the Commission.

Support. The following standard contracts are available:

  1. TR8 - Installation of Roadside Flashers for School Operation
  2. TR26 - Installation of Roadside Flashers for Emergency Vehicle Operation

Standard. Plans for installation shall be the responsibility of the outside party and shall conform to the latest standards of MoDOT.

Once the contract is executed, a permit to work on MoDOT’s right-of-way shall be obtained by the outside party. Once issued, the outside party may proceed to install the beacons. A contractor or the outside party shall complete the installation; however, a licensed electrician shall supervise the installation. The outside party needs to coordinate with MoDOT prior to installation of the flasher to have MoDOT personnel verify hardware and equipment is acceptable for use on the state highway system. Upon completion of installation, MoDOT personnel shall verify correct installation prior to release of the permit and acceptance of the flasher.

General layouts for an intersection control beacon are illustrated in Figure 902.18.2.

All costs shall be the responsibility of the outside party. This includes but is not limited to installation and power; however, the signs and mounting brackets shall be supplied by MoDOT. All specifications shall be met to ensure the proper installation is in place.

Beacons shall be active only during those times when the conditions of the advance signing are applicable or when the enhancement of the signed message is needed. The times of operation, timing, and method of operation are approved by MoDOT.

The contract shall establish responsibility for future maintenance, power costs, programming ownership, and replacement equipment.

Flashing beacons shall only be installed on advanced signing or on school speed limit signing.

Only one flasher assembly shall be permitted per approach.

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