903.16 Design Aspects of MoDOT Signing - Revision history

Hoskir: updated per RR4184

2026-05-06T13:31:13Z

updated per RR4184

← Older revision		Revision as of 08:31, 6 May 2026
Line 3:		Line 3:
	<div style="float: right; margin-top: 5px; margin-left: 15px; width:340px; font-size: 95%; background-color: #f8f9fa; padding: 0.3em; border: 1px solid #a2a9b1; text-align:left;">		<div style="float: right; margin-top: 5px; margin-left: 15px; width:340px; font-size: 95%; background-color: #f8f9fa; padding: 0.3em; border: 1px solid #a2a9b1; text-align:left;">
	'''<u><center>Forms</center></u>'''		'''<u><center>Forms</center></u>'''
	* [~~https://epg~~.~~modot~~.~~org/forms/general_files/TS/Signpost_Selection_Guide.xlsm Signpost Selection Guide]~~		* [[903.16_Design_Aspects_of_MoDOT_Signing#903.16.4.4_Ground-Mounted_Sign_Support_Selection\|Signpost Selection Tables]]
	* [[Media:903.~~2aPrintableSignpostSelectionGuide_2022~~.~~xls~~\|~~Printable~~ Signpost Selection ~~Guide for use in the field~~]]
	</div>		</div>

Hoskir: /* 903.16.4.9 Sign Mountings */ updated per RR4184

2026-05-06T13:24:22Z

903.16.4.9 Sign Mountings: updated per RR4184

← Older revision		Revision as of 08:24, 6 May 2026
Line 334:		Line 334:
	'''Support.''' 4 in. x 4 in. wood posts do not need any modification to be breakaway, however 4 in. x 6 in. wood posts will need to be cross drilled to meet breakaway standards. U-Channel posts do not require breakaway modifications if they are direct driven into the ground, however, if the ground stub and splice installation method is used the installation will need to be installed according to the [https://www.modot.org/standard-plans-section-900 Standard Plans 903] to meet breakaway requirements. PSST will require the addition of breakaway devices in certain applications based on the post size and number of posts used for an installation. The signpost selection tables will indicate when a breakaway is required for PSST posts. 4” Square Steel, Pipe and I-Beam posts have the breakaway devices integrated into the post design.		'''Support.''' 4 in. x 4 in. wood posts do not need any modification to be breakaway, however 4 in. x 6 in. wood posts will need to be cross drilled to meet breakaway standards. U-Channel posts do not require breakaway modifications if they are direct driven into the ground, however, if the ground stub and splice installation method is used the installation will need to be installed according to the [https://www.modot.org/standard-plans-section-900 Standard Plans 903] to meet breakaway requirements. PSST will require the addition of breakaway devices in certain applications based on the post size and number of posts used for an installation. The signpost selection tables will indicate when a breakaway is required for PSST posts. 4” Square Steel, Pipe and I-Beam posts have the breakaway devices integrated into the post design.

	===903.16.4.9 Sign ~~Mountings~~===		===903.16.4.9 Sign Orientation===
			'''Support.''' The orientation of the face of a sign in relation to the driver and roadway is critical to visibility and legibility, especially at night. The effectiveness of the retroreflective sheeting on a sign can be negatively impacted if the orientation of the sign face is not correct, due to incorrect installation and/or a signpost being damaged and knocked out of alignment.

	~~'''Support. '''Attaching a sign properly to~~ a sign ~~support is critical in order to properly orient~~ the sign in ~~relation~~ to ~~the driver as well as provide a durable, long life installation~~.		The orientation of a sign can also help reduce unwanted reflection or glare off of the sign face. The skew angle, shown in [https://www.modot.org/standard-plans-section-900 Standard Plans 903], is designed to help address this glare issue for tangent sections.

	'''Standard. '''Plastic/nylon washers shall be used between the heads of all twist fasteners (such as screws, bolts or nuts) and the sign face to protect the sheeting from the twisting action of the fasteners.		'''Option.''' While the standard skew angle is 93 degrees, the skew angle may be adjusted to maintain brightness and avoid glare for signs on curved sections of road.

			'''Support.''' See [[903.1 General (MUTCD Chapter 2A)#903.1.17\|EPG 903.1.17]] for additional information on Sign Orientation.

			===903.16.4.10 Sign Mountings===
			'''Support.''' Attaching a sign properly to a sign support is critical in order to properly orient the sign in relation to the driver as well as provide a durable, long life installation.

			'''Standard.''' Plastic/nylon washers shall be used between the heads of all twist fasteners (such as screws, bolts or nuts) and the sign face to protect the sheeting from the twisting action of the fasteners.

	Signs shall be attached to each type of sign support in accordance with [https://www.modot.org/standard-plans-section-900 Standard Plans 903].		Signs shall be attached to each type of sign support in accordance with [https://www.modot.org/standard-plans-section-900 Standard Plans 903].

	'''Support. '''See [[903.1 General (MUTCD Chapter 2A)#903.1.18\|EPG 903.1.18]] for additional information on Sign Mountings.		'''Support.''' See [[903.1 General (MUTCD Chapter 2A)#903.1.18\|EPG 903.1.18]] for additional information on Sign Mountings.

	=={{SpanID\|903.16.5}}903.16.5 Signing Plans==		=={{SpanID\|903.16.5}}903.16.5 Signing Plans==

Hoskir: /* 903.16.4.8 Sign Orientation */ updated per RR4184

2026-05-06T13:23:08Z

903.16.4.8 Sign Orientation: updated per RR4184

← Older revision		Revision as of 08:23, 6 May 2026
Line 327:		Line 327:
	'''Standard.''' When used, the flat sheet column mounting assembly shall be constructed and installed according to standard plans 903.03. Signs installed using this method shall also meet sign mounting height standards found in standard plans 903.03. Signs shall not be attached to lighting structures or utility poles as these structures are not designed to support highway signs.		'''Standard.''' When used, the flat sheet column mounting assembly shall be constructed and installed according to standard plans 903.03. Signs installed using this method shall also meet sign mounting height standards found in standard plans 903.03. Signs shall not be attached to lighting structures or utility poles as these structures are not designed to support highway signs.

	===903.16.4.8 ~~Sign Orientation~~===		===903.16.4.8 Breakaway Assemblies===
			'''Standard.''' All signposts installed on right of way shall meet federal breakaway standards and MoDOT design standards. Signposts which do not meet current breakaway standards, but which did meet the breakaway standards at the time of their installation, may remain in place until the end of their service life.

	~~'''Support. '''The orientation of the face of a sign in relation to the driver and roadway is critical to visibility~~ and ~~legibility, especially at night. The effectiveness of the retroreflective sheeting on a~~ sign ~~can~~ be ~~negatively impacted if the orientation of the sign face is not correct~~, ~~due to incorrect installation and/~~or ~~a signpost being damaged and knocked out of alignment~~.		Sign trusses and other large sign support structures that are not breakaway shall be protected by acceptable shielding, such as guard rail or barrier wall.

	~~The orientation of a sign can also help reduce unwanted reflection or glare off of the sign face~~. ~~The skew angle~~, ~~shown~~ in [https://www.modot.org/standard-plans-section-900 Standard Plans 903]~~, is designed~~ to ~~help address this glare issue for tangent sections~~.		'''Support.''' 4 in. x 4 in. wood posts do not need any modification to be breakaway, however 4 in. x 6 in. wood posts will need to be cross drilled to meet breakaway standards. U-Channel posts do not require breakaway modifications if they are direct driven into the ground, however, if the ground stub and splice installation method is used the installation will need to be installed according to the [https://www.modot.org/standard-plans-section-900 Standard Plans 903] to meet breakaway requirements. PSST will require the addition of breakaway devices in certain applications based on the post size and number of posts used for an installation. The signpost selection tables will indicate when a breakaway is required for PSST posts. 4” Square Steel, Pipe and I-Beam posts have the breakaway devices integrated into the post design.

	~~'''Option. '''While~~ the ~~standard skew angle is 93 degrees,~~ the ~~skew angle may be adjusted to maintain brightness~~ and ~~avoid glare~~ for ~~signs on curved sections of road~~.

	~~'''Support~~. ~~'''See [[903.1 General (MUTCD Chapter 2A)#903.1.17\|EPG 903.1.17]] for additional information on Sign Orientation~~.

	===903.16.4.9 Sign Mountings===		===903.16.4.9 Sign Mountings===

Hoskir: /* 903.16.4.7 Breakaway Assemblies */ updated per RR4184

2026-05-06T13:22:20Z

903.16.4.7 Breakaway Assemblies: updated per RR4184

← Older revision		Revision as of 08:22, 6 May 2026
Line 320:		Line 320:
	'''Support.''' Backing bars are typically used to support and stiffen wide flat sheet signs mounted on single signpost or to help support the individual signs which make up sign assemblies to form one unified sign assembly. Details for backing bars can be found in [https://www.modot.org/standard-plans-section-900 Standard Plans 903.02].		'''Support.''' Backing bars are typically used to support and stiffen wide flat sheet signs mounted on single signpost or to help support the individual signs which make up sign assemblies to form one unified sign assembly. Details for backing bars can be found in [https://www.modot.org/standard-plans-section-900 Standard Plans 903.02].

	===903.16.4.7 ~~Breakaway Assemblies~~===		===903.16.4.7 Flat Sheet Column Mounting Assembly===
			'''Support.''' Flat sheet column mounting assemblies were developed as a method to securely fasten large flat sheet signs to bridge columns or overhead sign truss columns commonly found on freeways and expressways. The column mounting assembly is made up of an aluminum C-channel which is banded to the column with a series of stainless-steel banding straps, providing a stronger point of contact with the structure. The sign is attached to the C-channel with aluminum backing bars. This sign attachment method is used for flat sheet signs 48” x 60” up to 48” x 96”, and any additional supplemental plaques associated with these signs, as well as 48” x 48” diamond warning signs. Smaller flat sheet signs are mounted to these column structures using traditional banding methods.

	'''~~Standard~~. '''~~All signposts installed on right~~ of ~~way shall meet federal breakaway standards and MoDOT standards. Signposts not meeting current standards, but met~~ the ~~standards at the time of their installation, may remain in place until the end of their service life~~.		'''Guidance.''' The flat sheet column mounting assembly should be used when attaching flat sheet signs of the sizes previously listed to bridge columns or sign truss columns to provide a secure sign attachment.

	~~Sign trusses and other large sign support structures that are not breakaway shall be protected by acceptable shielding, such as guard rail or barrier wall.~~		'''Standard.''' When used, the flat sheet column mounting assembly shall be constructed and installed according to standard plans 903.03. Signs installed using this method shall also meet sign mounting height standards found in standard plans 903.03. Signs shall not be attached to lighting structures or utility poles as these structures are not designed to support highway signs.

	'''~~Support~~. '''~~4 in. x 4 in. wood posts do not need any modification to be breakaway~~, ~~however 4 in. x 6 in. and 6 in. x 6 in. wood posts will need to~~ be ~~cross drilled to meet breakaway standards. U-Channel posts do not require breakaway modifications if they are direct driven into the ground, however, if the ground stub~~ and ~~slice installation method is used the installation will need to be~~ installed according to ~~the [https://www~~.~~modot~~.~~org/~~standard-plans~~-section-900 Standard Plans~~ 903~~] to meet breakaway requirements~~. ~~PSST will require breakaway devices added in certain applications based on sign and number of posts used for an installation~~. ~~The signpost selection tools will indicate when a breakaway is required for PSST posts. Pipe and Wide Flange posts have the breakaway devices integrated into the post design~~.

	===903.16.4.8 Sign Orientation===		===903.16.4.8 Sign Orientation===

Hoskir: /* 903.16.4.6 Backing Bars */ updated per RR4184

2026-05-06T13:21:16Z

903.16.4.6 Backing Bars: updated per RR4184

← Older revision		Revision as of 08:21, 6 May 2026
Line 318:		Line 318:
	===903.16.4.6 Backing Bars===		===903.16.4.6 Backing Bars===

	'''Support. '''Backing bars are typically used to support and stiffen wide flat sheet signs mounted on single signpost or to help support the individual signs which make up sign assemblies to form one unified sign assembly. Details for backing bars can be found in [https://www.modot.org/standard-plans-section-900 Standard Plans 903].		'''Support.''' Backing bars are typically used to support and stiffen wide flat sheet signs mounted on single signpost or to help support the individual signs which make up sign assemblies to form one unified sign assembly. Details for backing bars can be found in [https://www.modot.org/standard-plans-section-900 Standard Plans 903.02].

	===903.16.4.7 Breakaway Assemblies===		===903.16.4.7 Breakaway Assemblies===

Hoskir: /* 903.16.4.5 Secondary Sign Supports – Post Extensions */ updated per RR4184

2026-05-06T13:20:20Z

903.16.4.5 Secondary Sign Supports – Post Extensions: updated per RR4184

← Older revision		Revision as of 08:20, 6 May 2026
Line 308:		Line 308:
	===903.16.4.5 Secondary Sign Supports – Post Extensions===		===903.16.4.5 Secondary Sign Supports – Post Extensions===

	'''Support. '''~~These supports~~ are 3 in. aluminum I-Beam used to attach exit number panels to the top of, or to hang a secondary sign below, structural signs on new installations. Details of these posts are shown in the [https://www.modot.org/standard-plans-section-900 Standard Plans 903].		'''Support.''' Post extensions are 3 in. aluminum I-Beam used to attach exit number panels to the top of, or to hang a secondary sign below, structural signs on new installations. Details of these posts are shown in the [https://www.modot.org/standard-plans-section-900 Standard Plans 903].

	'''Option. '''There are occasions where modifications and/or additions must be made to existing sign installations where the existing posts are not long enough to support the new sign assembly. In these cases, it is permissible to utilize secondary sign supports to effectively extend the primary signposts to support signs a maximum of 3 feet taller than the existing primary signposts.		'''Option.''' There are occasions where modifications and/or additions must be made to existing sign installations where the existing posts are not long enough to support the new sign assembly. In these cases, it is permissible to utilize secondary sign supports to effectively extend the primary signposts to support signs a maximum of 3 feet taller than the existing primary signposts.

	Secondary sign supports may only be used to allow taller signs to be installed on existing signposts if the signposts have the capacity to carry the larger sign based on signpost selection ~~tools~~.		Secondary sign supports may only be used to allow taller signs to be installed on existing signposts and only if the existing signposts meet installation standards and have the capacity to carry the larger sign based on signpost selection tables.

	If a new sign assembly is more than 3 ft taller than the existing primary signposts, new signposts shall be installed.		If a new sign assembly is more than 3 ft taller than the existing primary signposts, new signposts shall be installed.

Hoskir: /* 903.16.4.4 Ground-Mounted Sign Support Selection */ updated per RR4184

2026-05-06T13:18:33Z

903.16.4.4 Ground-Mounted Sign Support Selection: updated per RR4184

Show changes

Hoskir: /* {{SpanID|903.16.3}}903.16.3 Types of Fabricated Signs */ updated per RR4184

2026-05-06T13:11:59Z

{{SpanID|903.16.3}}903.16.3 Types of Fabricated Signs: updated per RR4184

← Older revision		Revision as of 08:11, 6 May 2026
Line 80:		Line 80:
	=={{SpanID\|903.16.3}}903.16.3 Types of Fabricated Signs==		=={{SpanID\|903.16.3}}903.16.3 Types of Fabricated Signs==

	'''Support. '''There are two types of sign ~~material available,~~ structural (ST) and sheet (SH).		'''Support.''' There are two types of sign substrate materials used by MoDOT - extruded aluminum panels and flat sheet aluminum. From these materials there are four types of signs fabricated - structural (ST) and structural fluorescent (STF), which are made from extruded aluminum panels, as well as flat sheet (SH) and flat sheet fluorescent (SHF).

	~~Sheet~~ signs are sheet aluminum, usually one-piece units, and have several available thicknesses as indicated in the standard plans.		Flat sheet signs are made from single pieces of flat sheet aluminum, usually one-piece units, with the thickness of the aluminum sheet varying based on the size of the sign, and have several available thicknesses as indicated in the standard plans.

	Structural signs are ~~usually made of multiple~~ extruded panels. ~~These signs are~~ used ~~primarily~~ for ~~guide~~ signs ~~on expressways and freeways, but may be found on other routes on a limited basis, and are used on all overhead-mounted signs, including “LOW CLEARANCE” and exit number panels, signs greater than~~ 6 ft. wide, and signs ~~greater than~~ 30 sq. ft. in area.		Structural signs are fabricated using extruded aluminum panels. This sign fabrication method is used for signs 6 ft. wide or wider, and signs 30 sq. ft. in area and larger due to the structural strength of the extruded panels. Extruded panels are composed of 1-ft. tall "E" shaped aluminum substrate, assembled to a desired height and cut to a uniform width for each sign. These panels are bolted together to form the larger “sign blank” substrate needed for structural signs. 6-in. tall “C” shaped panels are also used in limited applications where the sign’s vertical dimension has a 6-in. increment, such as exit number plaques on guide signs.

	~~Extruded panels~~ are ~~composed~~ of ~~a 1 ft. tall "E" shaped aluminum substrate~~, ~~assembled to a desired height~~ and ~~cut to a uniform width~~ for ~~each sign~~. ~~These panels are bolted together to form~~ the ~~larger “blank” substrate needed~~ for ~~structural~~ signs.		There are two types of retroreflective sheeting used by MoDOT:
			* MoDOT Type IV High Intensity Prismatic - this sheeting is used for the background for all signs, except orange work zone, yellow warning and yellow-green school signs.
			* MoDOT Type IX or XI Prismatic - this sheeting is used for all direct applied legends used on guide signs. It is also used for the background sheeting for orange work zone, yellow warning, and yellow-green school signs as MoDOT uses the fluorescent versions of these colors that are only available in this sheeting type.

	~~There are two types of reflective sheeting available to MoDOT~~:		See [https://www.modot.org/standard-plans-section-900 MoDOT Standard Plans 903.02] for details on sign substrate and retroreflective sheeting.
	# MoDOT ~~Type III High Intensity Prismatic (R2)~~
	~~# MoDOT Type VII Prismatic (R4).~~

	~~'''Guidance~~. ~~'''Generally, R2 sheeting should be used~~ on ~~all~~ sign ~~backgrounds. R3~~ sheeting ~~should be used on all legend and symbols on guide signs~~.

	=={{SpanID\|903.16.4}}903.16.4 Ground Mounted Sign Supports==		=={{SpanID\|903.16.4}}903.16.4 Ground Mounted Sign Supports==

Hoskir: /* 903.16.4.4 Ground-Mounted Sign Support Selection */ updated link to signpost selection guide

2026-04-15T15:52:24Z

903.16.4.4 Ground-Mounted Sign Support Selection: updated link to signpost selection guide

← Older revision		Revision as of 10:52, 15 April 2026
Line 165:		Line 165:
	<div style="float: right; margin-top: 5px; margin-left: 15px; width:340px; font-size: 95%; background-color: #f8f9fa; padding: 0.3em; border: 1px solid #a2a9b1; text-align:left;">		<div style="float: right; margin-top: 5px; margin-left: 15px; width:340px; font-size: 95%; background-color: #f8f9fa; padding: 0.3em; border: 1px solid #a2a9b1; text-align:left;">
	'''<u><center>Forms</center></u>'''		'''<u><center>Forms</center></u>'''
	* [~~[Media~~:~~903~~.~~2a_Signpost_Selection_Guide_2022-5-23~~.~~xls\|~~Signpost Selection Guide]]		* [https://epg.modot.org/forms/general_files/TS/Signpost_Selection_Guide.xlsm Signpost Selection Guide]
	* [[Media:903.2aPrintableSignpostSelectionGuide_2022.xls\|Printable Signpost Selection Guide for use in the field]]		* [[Media:903.2aPrintableSignpostSelectionGuide_2022.xls\|Printable Signpost Selection Guide for use in the field]]
	</div>		</div>

Hoskir: /* {{SpanID|903.16.1}}903.16.1 Scope of Signs and Signing */ updated link to signpost selection guide

2026-04-15T15:33:50Z

{{SpanID|903.16.1}}903.16.1 Scope of Signs and Signing: updated link to signpost selection guide

← Older revision		Revision as of 10:33, 15 April 2026
Line 3:		Line 3:
	<div style="float: right; margin-top: 5px; margin-left: 15px; width:340px; font-size: 95%; background-color: #f8f9fa; padding: 0.3em; border: 1px solid #a2a9b1; text-align:left;">		<div style="float: right; margin-top: 5px; margin-left: 15px; width:340px; font-size: 95%; background-color: #f8f9fa; padding: 0.3em; border: 1px solid #a2a9b1; text-align:left;">
	'''<u><center>Forms</center></u>'''		'''<u><center>Forms</center></u>'''
	* [~~[Media~~:~~903~~.~~2a_Signpost_Selection_Guide_2022-5-23~~.~~xls\|~~Signpost Selection Guide]]		* [https://epg.modot.org/forms/general_files/TS/Signpost_Selection_Guide.xlsm Signpost Selection Guide]
	* [[Media:903.2aPrintableSignpostSelectionGuide_2022.xls\|Printable Signpost Selection Guide for use in the field]]		* [[Media:903.2aPrintableSignpostSelectionGuide_2022.xls\|Printable Signpost Selection Guide for use in the field]]
	</div>		</div>