902.26 Construction Inspection Guidelines for Sec 902 - Revision history

RollerA: /* Detector Installation (for Sec 902.13) */

2025-11-25T19:14:03Z

Detector Installation (for Sec 902.13)

← Older revision		Revision as of 14:14, 25 November 2025
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	===Induction Loop Detector (for Sec 902.13.2)===		===Induction Loop Detector (for Sec 902.13.2)===
	[[~~image~~:~~902.13.2 induction~~ loop installation.jpg\|right\|300px\|thumb\|<center>'''Induction loop installation'''</center>]]		[[File:Induction loop installation.jpg\|right\|300px\|thumb\|<center>'''Induction loop installation'''</center>]]

	This type of detector consists of a loop of cable embedded within the roadway. When the loop is connected to the detector amplifier in the cabinet it completes a tuned circuit. When a vehicle enters the loop area, a resultant shift in the resonant frequency of this tuned circuit is detected and the detector amplifier places a call in the controller. The locations of traffic signal loop detectors and the locations of the stop bars at intersections are critical. Improper location of these two features in relation to each other can cause operational problems with the traffic signals. Ideally, the two features are located so that when a vehicle stops at the stop bar, the stopped vehicle is fully in the detection zone of the loop. Care also needs to be taken when side street left turns are present. Locating the stop bars too far forward in these situations can either make it difficult for the side street traffic to execute their left turn or the turning traffic could clip the loop, thereby putting a false detection into the signal.		This type of detector consists of a loop of cable embedded within the roadway. When the loop is connected to the detector amplifier in the cabinet it completes a tuned circuit. When a vehicle enters the loop area, a resultant shift in the resonant frequency of this tuned circuit is detected and the detector amplifier places a call in the controller. The locations of traffic signal loop detectors and the locations of the stop bars at intersections are critical. Improper location of these two features in relation to each other can cause operational problems with the traffic signals. Ideally, the two features are located so that when a vehicle stops at the stop bar, the stopped vehicle is fully in the detection zone of the loop. Care also needs to be taken when side street left turns are present. Locating the stop bars too far forward in these situations can either make it difficult for the side street traffic to execute their left turn or the turning traffic could clip the loop, thereby putting a false detection into the signal.

RollerA: /* Preemption Equipment */

2025-11-25T19:13:01Z

Preemption Equipment

← Older revision		Revision as of 14:13, 25 November 2025
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	All equipped approaches should be tested.		All equipped approaches should be tested.
	[[~~image~~:902.~~13 train~~.jpg\|right\|175px]]		[[File:Figure 902.26.3.jpg\|right\|175px]]

	===Railroad Pre-emption===		===Railroad Pre-emption===

RollerA: /* Installation of Posts and Signal Heads (for Sec 902.5) */

2025-11-25T19:11:56Z

Installation of Posts and Signal Heads (for Sec 902.5)

← Older revision		Revision as of 14:11, 25 November 2025
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	{\|align="right"		{\|align="right"
	\|-		\|-
	\|[[~~image~~:902.~~13 Signal Head - nipple~~.jpg\|220px\|thumb\|<center>'''Signal heads attached using pipe nipples manufactured by the pole company, requiring the pole company to have specific measurements for the placement of the signal heads. Pipe nipples do not allow for adjustment in the field.'''</center>]]\|\|[[~~image~~:902.~~13 Signal Head - bracket~~.jpg\|220px\|thumb\|<center>'''Signal heads attached with cable brackets, reducing manufacturing costs and allowing field adjustment.'''</center>]]		\|[[File:Figure 902.26.1.jpg\|220px\|thumb\|<center>'''Signal heads attached using pipe nipples manufactured by the pole company, requiring the pole company to have specific measurements for the placement of the signal heads. Pipe nipples do not allow for adjustment in the field.'''</center>]]\|\|[[File:Figure 902.26.2.jpg\|220px\|thumb\|<center>'''Signal heads attached with cable brackets, reducing manufacturing costs and allowing field adjustment.'''</center>]]
	\|}		\|}

RollerA at 19:09, 25 November 2025

2025-11-25T19:09:24Z

← Older revision		Revision as of 14:09, 25 November 2025
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	[[~~image~~:902.13.~~1.1~~.jpg\|right\|450px\|thumb\|<center>'''Slot Cutting as discussed in Sec 902.13.2'''</center>]]		[[File:Slot Cutting as discussed in Sec 902.13.2.jpg\|right\|450px\|thumb\|<center>'''Slot Cutting as discussed in Sec 902.13.2'''</center>]]

	==General ([https://www.modot.org/missouri-standard-specifications-highway-construction Sec 902.2])==		==General ([https://www.modot.org/missouri-standard-specifications-highway-construction Sec 902.2])==
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	Regardless of the type of control equipment specified or geometrics of the intersection involved, construction procedure is approximately the same for all signal projects. The order of work consists of: (a) laying or pushing conduit network; (b) excavating, forming, and placing of pullboxes, post bases, and controller bases; (c) erection of signal posts; (d) installation of electrical service; (e) installing signal heads; (f) installing detectors; (g) pulling cable into conduits; (h) tagging and wiring signal heads, detectors, interconnection system, and controller; (i) checkout of individual components and final checkout of the entire system. It is the intent of this article to set out inspection procedures in the same general order as work is usually done.		Regardless of the type of control equipment specified or geometrics of the intersection involved, construction procedure is approximately the same for all signal projects. The order of work consists of: (a) laying or pushing conduit network; (b) excavating, forming, and placing of pullboxes, post bases, and controller bases; (c) erection of signal posts; (d) installation of electrical service; (e) installing signal heads; (f) installing detectors; (g) pulling cable into conduits; (h) tagging and wiring signal heads, detectors, interconnection system, and controller; (i) checkout of individual components and final checkout of the entire system. It is the intent of this article to set out inspection procedures in the same general order as work is usually done.
	[[~~image~~:~~902.13~~ post bases.jpg\|right\|275px\|thumb\|<center>'''Type A and Type B post bases'''</center>]]		[[File:Type A and Type B post bases.jpg\|right\|275px\|thumb\|<center>'''Type A and Type B post bases'''</center>]]
	The inspector assigned to a signal project should thoroughly study the contract. If the inspector has had no previous signal work, they can gain much by study of a previously completed installation. Discussions with [http://sp/sites/ts/Pages/default.aspx Traffic] are very helpful. They can explain the various types of equipment to be used and give the inspector a better understanding of nomenclature used in signal work.		The inspector assigned to a signal project should thoroughly study the contract. If the inspector has had no previous signal work, they can gain much by study of a previously completed installation. Discussions with [http://sp/sites/ts/Pages/default.aspx Traffic] are very helpful. They can explain the various types of equipment to be used and give the inspector a better understanding of nomenclature used in signal work.

TaracksA at 20:31, 13 October 2025

2025-10-13T20:31:29Z

← Older revision		Revision as of 15:31, 13 October 2025
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	==Staking==		==Staking==
	Staking and layout work for a traffic signal project should be done with the idea always in mind to avoid conflicts with roadway items, and with signing and lighting if they are included in the project. Each signal post location shall be staked and carefully checked to see that signal heads to be mounted thereon will be in clear view from the lane, or lanes, to be controlled. Posts should not be located in sidewalks if it can be avoided without reducing visibility of signal heads. Pullbox, conduit runs, and controller base locations may have to be shifted to avoid conflict with other items. Care should be taken to avoid placing signal ~~appurtances~~ in a drainage ditch. If necessary, shift the controller base to a location where chances of its being struck by a vehicle are reduced to a minimum. If the controller base is so situated that it cannot be moved refer to [https://epg.modot.org/index.php/902.15_Designing_a_Traffic_Signal#902.15.2.2_Location_of_Controllers EPG 902.15.2.2] for countermeasure expectations.		Staking and layout work for a traffic signal project should be done with the idea always in mind to avoid conflicts with roadway items, and with signing and lighting if they are included in the project. Each signal post location shall be staked and carefully checked to see that signal heads to be mounted thereon will be in clear view from the lane, or lanes, to be controlled. Posts should not be located in sidewalks if it can be avoided without reducing visibility of signal heads. Pullbox, conduit runs, and controller base locations may have to be shifted to avoid conflict with other items. Care should be taken to avoid placing signal appurtenances in a drainage ditch. If necessary, shift the controller base to a location where chances of its being struck by a vehicle are reduced to a minimum. If the controller base is so situated that it cannot be moved refer to [https://epg.modot.org/index.php/902.15_Designing_a_Traffic_Signal#902.15.2.2_Location_of_Controllers EPG 902.15.2.2] for countermeasure expectations.

	==[[902.12 Glossary\|Glossary]]==		==[[902.12 Glossary\|Glossary]]==
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	Fire or emergency vehicle pre-emption can be initiated by a switch located in a nearby fire station or emergency facility or by a special emitter that can be mounted on emergency vehicles.		Fire or emergency vehicle pre-emption can be initiated by a switch located in a nearby fire station or emergency facility or by a special emitter that can be mounted on emergency vehicles.

	===Manual ~~switch~~===		===Manual Switch===

	The manual switch is connected to the signal control cabinet by cabling or via a radio connection. Activating the switch will initiate a pre-empt sequence in the affected. Pre-emption timing, in this case, depends upon the time it will take for an emergency vehicle to leave its building and clear the controlled intersection. This is best determined from an actual test run by an emergency vehicle.		The manual switch is connected to the signal control cabinet by cabling or via a radio connection. Activating the switch will initiate a pre-empt sequence in the affected. Pre-emption timing, in this case, depends upon the time it will take for an emergency vehicle to leave its building and clear the controlled intersection. This is best determined from an actual test run by an emergency vehicle.
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	===Other types of detector installation===		===Other types of detector installation===

	For other types of detectors, including microwave and ultrasonic detectors (Sec 902.13.3) and video ~~dectection~~ systems (Sec 902.13.4), the inspector should follow the recommendations of the manufacturer.		For other types of detectors, including microwave and ultrasonic detectors (Sec 902.13.3) and video detection systems (Sec 902.13.4), the inspector should follow the recommendations of the manufacturer.

	==Pull and Junction Boxes (for Sec 902.14)==		==Pull and Junction Boxes (for Sec 902.14)==
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	:A) Every year		:A) Every year
	:B) During field signal observations		:B) During field signal observations
	:C) When field signal preventive maintenance is ~~preformed~~		:C) When field signal preventive maintenance is performed
	:D) After any field changes to signal timing.		:D) After any field changes to signal timing.

TaracksA at 18:24, 6 October 2025

2025-10-06T18:24:50Z

← Older revision		Revision as of 13:24, 6 October 2025
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	If an accessible pedestrian signal has been damaged or is not working properly, it should be replaced as quickly as possible.		If an accessible pedestrian signal has been damaged or is not working properly, it should be replaced as quickly as possible.

	[[Category:902 Signals\|902.26]]		[[Category:902 Signals (MUTCD Part 4)\|902.26]]

TaracksA: Page Creation

2025-09-17T21:51:53Z

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