Road construction - Revision history

Designing Buildings at 08:17, 13 December 2022

2022-12-13T08:17:51Z

← Older revision		Revision as of 08:17, 13 December 2022
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	[[File:Road_surfacing.jpg\|link=File:Road_surfacing.jpg]]		[[File:Road_surfacing.jpg\|link=File:Road_surfacing.jpg]]

−	= ~~Introduction~~ =	+	= The history of road construction =

	The methods of constructing roads have changed a lot since the first roads were built around 4,000 BC – made of stone and timber.		The methods of constructing roads have changed a lot since the first roads were built around 4,000 BC – made of stone and timber.

	The first Roman roads were stone paved, built in North Africa and Europe for military operations. Road construction techniques were gradually improved by the study of road traffic, stone thickness, road alignment, and slope gradients, developing to use stones that were laid in a regular, compact design, and covered with smaller stones to produce a solid layer.		The first Roman roads were stone paved, built in North Africa and Europe for military operations. Road construction techniques were gradually improved by the study of road traffic, stone thickness, road alignment, and slope gradients, developing to use stones that were laid in a regular, compact design, and covered with smaller stones to produce a solid layer.
		+
		+	= Modern road construction =

	Modern roads tend to be constructed using asphalt and/or concrete.		Modern roads tend to be constructed using asphalt and/or concrete.

−	Very broadly, the construction of roads ~~can be described by~~ three processes:	+	Very broadly, the construction of roads includes three processes:

	* Setting out.		* Setting out.
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	The level of each profile board is controlled using a line level which is a short spirit level hung from a nylon string. The line operator moves the string up or down until the bubble is centred.		The level of each profile board is controlled using a line level which is a short spirit level hung from a nylon string. The line operator moves the string up or down until the bubble is centred.

−	Junctions, hammer heads, turning bays and intersecting curves ~~are~~ laid out in a similar manner.	+	Junctions, hammer heads, turning bays and intersecting curves can be laid out in a similar manner.

	= Earthworks =		= Earthworks =

−	~~Earthwork is one of the major works involved in road construction. It involves~~ the removal of topsoil, along with any vegetation, before scraping and grading the area to the finished ‘formation level’. This is usually done using a tractor shovel, grader or bulldozer. Below the formation level, the soil is known as the ‘subgrade’. It is essential that the strength of the subgrade is tested prior to ~~earthwork~~ beginning.	+	Earthworks involve the removal of topsoil, along with any vegetation, before scraping and grading the area to the finished ‘formation level’. This is usually done using a tractor shovel, grader or bulldozer. Below the formation level, the soil is known as the ‘subgrade’. It is essential that the strength of the subgrade is tested prior to earthworks beginning.

	Most earthworks are formed by cut-and-fill, and the type of ‘fill’ material must be considered, not only in terms of its physical properties, but on the conditions in which it is to be used, and the methods of compaction.		Most earthworks are formed by cut-and-fill, and the type of ‘fill’ material must be considered, not only in terms of its physical properties, but on the conditions in which it is to be used, and the methods of compaction.
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	* Soil stabilisation methods such as the use of cement, bituminous materials or chemicals.		* Soil stabilisation methods such as the use of cement, bituminous materials or chemicals.

−	~~For more information, see Types of soil.~~	+	Subgrade strength will decrease as moisture content increases so protection may be required if it is to left exposed for any length of time. Protection covering can be either:
−		+
−	~~The subgrade~~ strength will decrease as moisture content increases so protection may be required if it is to left exposed for any length of time.	+
−		+
−	Protection covering can be either:	+

	* Medium gauge plastic sheeting with 300 mm laps.		* Medium gauge plastic sheeting with 300 mm laps.
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	Once the subgrade has been prepared and drainage or buried services installed, the paving construction can begin. Paving can be either flexible or rigid. There are pros and cons to each type, with one being selected over the other depending on the specific needs of a project.		Once the subgrade has been prepared and drainage or buried services installed, the paving construction can begin. Paving can be either flexible or rigid. There are pros and cons to each type, with one being selected over the other depending on the specific needs of a project.

−	Rigid pavements tend to have lower maintenance costs, a longer design life and higher flexural strength; but flexible pavements tend to have lower construction costs and ~~have~~ a ~~higher~~ ability to expand and contract with temperature and so do not need expansion joints.	+	Rigid pavements tend to have lower maintenance costs, a longer design life and higher flexural strength; but flexible pavements tend to have lower construction costs and a better ability to expand and contract with temperature and so do not need expansion joints.

	== Flexible paving ==		== Flexible paving ==

−	Flexible paving consists of materials applied in layers directly over the subgrade to which the traffic loads are distributed. To prevent permanent deformation, and therefore an uneven running surface, the thicknesses of individual layers must be capable of distributing such loads. The subgrade is compacted with the sub-base on top of it. On top of this ~~is laid~~ the surfacing which is made up of the base layer and the wearing course.	+	Flexible paving consists of materials applied in layers directly over the subgrade onto which the traffic loads are distributed. To prevent permanent deformation, and therefore an uneven running surface, the thicknesses of individual layers must be capable of distributing such loads. The subgrade is compacted with the sub-base on top of it. On top of this the surfacing is laid which is made up of the base layer and the wearing course.

	=== Surfacing ===		=== Surfacing ===
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	The wearing course is the upper layer of bituminous material, often denser and stronger than the base layer. The thickness depends on the material specification and the amount of wear that is expected. Desired properties are good non-skid capabilities, minimal glare and acceptable durability.		The wearing course is the upper layer of bituminous material, often denser and stronger than the base layer. The thickness depends on the material specification and the amount of wear that is expected. Desired properties are good non-skid capabilities, minimal glare and acceptable durability.

−	The main materials that are used are hot rolled asphalt (HRA), dense bitumen macadam (DBM), dense tar macadam (DTM) and porous asphalt (PA). PA is especially suitable as it is an open-graded material that is designed to allow rapid drainage of surface water, thereby reducing spray as well as tyre noise.	+	The main materials that are used are hot rolled asphalt (HRA), dense bitumen macadam (DBM), dense tar macadam (DTM) and porous asphalt (PA). Porous asphalt is especially suitable as it is an open-graded material that is designed to allow rapid drainage of surface water, thereby reducing spray as well as tyre noise.

	The base will typically have a minimum thickness of 60 mm and is usually made of dense bitumen macadam or asphalt. It is laid with the appropriate crossfalls and gradients.		The base will typically have a minimum thickness of 60 mm and is usually made of dense bitumen macadam or asphalt. It is laid with the appropriate crossfalls and gradients.
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	=== Sub-base ===		=== Sub-base ===

−	This is placed in a layer usually not exceeding 150 mm over the subgrade after waterproofing is complete. Various materials can be used but it is common for crushed stone or dry lean concrete (such as 1 : 15) laid and compacted by heavy rollers. Cellular Concrete (Foamed Concrete) is another material that can be used for the sub-base, the thickness and strength required depends upon the type of road.	+	This is placed in a layer usually not exceeding 150 mm over the subgrade after waterproofing is complete. Various materials can be used but it is common for crushed stone or dry lean concrete (such as 1:15) laid and compacted by heavy rollers. Cellular Concrete (Foamed Concrete) is another material that can be used for the sub-base, the thickness and strength required depends upon the type of road.

	== Rigid paving ==		== Rigid paving ==

−	Rigid paving consists of a reinforced or unreinforced insitu concrete ~~slab~~ laid over a thin granular base ~~course~~. The rigidity and strength of the pavement enables the loads and stresses to be distributed over a wide area of the subgrade.	+	Rigid paving consists of a reinforced or unreinforced insitu concrete laid over a thin granular base. The rigidity and strength of the pavement enables the loads and stresses to be distributed over a wide area of the subgrade.

−	Rigid paving is made up of the following layers (from bottom to top):	+	Rigid paving is typically made up of the following layers (from bottom to top):

	* Subgrade.		* Subgrade.
	* Sub-base of thick crushed stone. Usually to a thickness of 80 mm.		* Sub-base of thick crushed stone. Usually to a thickness of 80 mm.
−	* Anti-friction membrane normally made of polythene sheeting. ~~Also~~ prevents grout loss from freshly laid concrete.	+	* Anti-friction membrane normally made of polythene sheeting. This also prevents grout loss from the freshly laid concrete.
	* Insitu concrete paving slab. Reinforcement in the form of either steel fabric or re-bar may be used.		* Insitu concrete paving slab. Reinforcement in the form of either steel fabric or re-bar may be used.
	* Asphalt or similar topping if required.		* Asphalt or similar topping if required.
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	Longitudinal and transverse joints are required in rigid paving between the slabs, limiting the stresses applied due to subgrade restraint (friction between the pavement and subgrade), and providing room for expansion and contraction movements. The spacing of road joints is determined by:		Longitudinal and transverse joints are required in rigid paving between the slabs, limiting the stresses applied due to subgrade restraint (friction between the pavement and subgrade), and providing room for expansion and contraction movements. The spacing of road joints is determined by:

−	* ~~Thickness~~ of the slab.	+	* The hickness of the slab.
	* Whether there is reinforcement in the slab or not.		* Whether there is reinforcement in the slab or not.
	* The expected traffic load and flow rate.		* The expected traffic load and flow rate.
−	* The temperature at which concrete is laid.	+	* The temperature at which the concrete is laid.

−	For more information, see ~~Road joints.~~	+	For more information, see

−	~~For more information, see~~ Highway drainage.	+	* Road joints.
−		+	* Highway drainage.
−	~~For more information, see~~ Kerbs.	+	* Kerbs.

	= Related articles on Designing Buildings =		= Related articles on Designing Buildings =
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	* Choosing road surfacing specialists.		* Choosing road surfacing specialists.
	* Code of Practice for Ironwork Systems Installation and Refurbishment.		* Code of Practice for Ironwork Systems Installation and Refurbishment.
−	* Cul-de-sac.
−	* Deck.
−	* Design and Check Certificates.
	* Glossary of paving terms.		* Glossary of paving terms.
	* Gravel v hardcore v aggregates.		* Gravel v hardcore v aggregates.
	* Highway authority.		* Highway authority.
	* Highway drainage.		* Highway drainage.
−	* Infrastructure and Projects Authority.
	* Mobile asphalt stations.		* Mobile asphalt stations.
	* Movement joint.		* Movement joint.
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	* Overview of the road development process.		* Overview of the road development process.
	* Pavement.		* Pavement.
−	* Road improvement scheme consultation.
	* Road joints.		* Road joints.
	* Road traffic management.		* Road traffic management.

Daniel Wells at 17:18, 9 November 2022

2022-11-09T17:18:12Z

← Older revision		Revision as of 17:18, 9 November 2022
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	=== Sub-base ===		=== Sub-base ===

−	This is placed in a layer usually not exceeding 150 mm over the subgrade after waterproofing is complete. Various materials can be used but it is common for crushed stone or dry lean concrete (such as 1 : 15) laid and compacted by heavy rollers.	+	This is placed in a layer usually not exceeding 150 mm over the subgrade after waterproofing is complete. Various materials can be used but it is common for crushed stone or dry lean concrete (such as 1 : 15) laid and compacted by heavy rollers. Cellular Concrete (Foamed Concrete) is another material that can be used for the sub-base, the thickness and strength required depends upon the type of road.

	== Rigid paving ==		== Rigid paving ==

Editor at 19:44, 7 January 2022

2022-01-07T19:44:25Z

← Older revision		Revision as of 19:44, 7 January 2022
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	* Road traffic management.		* Road traffic management.
	* Roadworks.		* Roadworks.
		+	* Street works.
	* Successful road kerb trial.		* Successful road kerb trial.
	* Types of road and street.		* Types of road and street.

Editor at 18:25, 7 January 2022

2022-01-07T18:25:50Z

← Older revision		Revision as of 18:25, 7 January 2022
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	* Road joints.		* Road joints.
	* Road traffic management.		* Road traffic management.
		+	* Roadworks.
	* Successful road kerb trial.		* Successful road kerb trial.
	* Types of road and street.		* Types of road and street.

Editor at 11:38, 4 January 2022

2022-01-04T11:38:02Z

← Older revision		Revision as of 11:38, 4 January 2022
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	For more information, see Kerbs.		For more information, see Kerbs.

−	= Related articles on Designing Buildings ~~Wiki~~ =	+	= Related articles on Designing Buildings =

	* Bitumen binder may delay road surface deterioration.		* Bitumen binder may delay road surface deterioration.
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	* Types of road and street.		* Types of road and street.
	* Vision and validate: a third way in designing the roads of the future.		* Vision and validate: a third way in designing the roads of the future.
		+	* What are smart motorways and how do they work?

	= External references =		= External references =

80.79.209.48 at 17:43, 13 July 2021

2021-07-13T17:43:02Z

← Older revision		Revision as of 17:43, 13 July 2021
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	Rigid paving consists of a reinforced or unreinforced insitu concrete slab laid over a thin granular base course. The rigidity and strength of the pavement enables the loads and stresses to be distributed over a wide area of the subgrade.		Rigid paving consists of a reinforced or unreinforced insitu concrete slab laid over a thin granular base course. The rigidity and strength of the pavement enables the loads and stresses to be distributed over a wide area of the subgrade.

−	Rigid paving is made up of the following layers (from ~~top to~~ bottom):	+	Rigid paving is made up of the following layers (from bottom to top):

	* Subgrade.		* Subgrade.

Editor at 10:33, 18 June 2021

2021-06-18T10:33:53Z

← Older revision		Revision as of 10:33, 18 June 2021
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	* Successful road kerb trial.		* Successful road kerb trial.
	* Types of road and street.		* Types of road and street.
		+	* Vision and validate: a third way in designing the roads of the future.

	= External references =		= External references =

Editor at 16:06, 24 May 2021

2021-05-24T16:06:37Z

← Older revision		Revision as of 16:06, 24 May 2021
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	* Highway drainage.		* Highway drainage.
	* Infrastructure and Projects Authority.		* Infrastructure and Projects Authority.
		+	* Mobile asphalt stations.
	* Movement joint.		* Movement joint.
	* NEC contracts - road development and management schemes.		* NEC contracts - road development and management schemes.

Editor at 15:09, 29 April 2021

2021-04-29T15:09:52Z

← Older revision		Revision as of 15:09, 29 April 2021
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	= Related articles on Designing Buildings Wiki =		= Related articles on Designing Buildings Wiki =

		+	* Bitumen binder may delay road surface deterioration.
	* Bituminous mixing and laying plant.		* Bituminous mixing and laying plant.
	* Britain's historic paving.		* Britain's historic paving.

Editor at 20:31, 5 January 2021

2021-01-05T20:31:30Z

← Older revision		Revision as of 20:31, 5 January 2021
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	* Cul-de-sac.		* Cul-de-sac.
	* Deck.		* Deck.
		+	* Design and Check Certificates.
	* Glossary of paving terms.		* Glossary of paving terms.
	* Gravel v hardcore v aggregates.		* Gravel v hardcore v aggregates.