A 'road' is an identifiable
route, way or
path between two or more
places.
[ Major Roads of the United States ] Roads are typically smoothed,
paved, or otherwise prepared to allow easy
travel;
[ Road Infrastructure Strategic Framework for South Africa ] though they need not be, and historically many roads were simply recognizable routes without any formal
construction or
maintenance. In
urban areas roads may pass through a
city or
village and be named as
streets, serving a dual function as urban space
easement and route.
[ What is the difference between a road and a street? ] Economics and
society depend heavily on efficient roads. In the
European Union (EU) 44 % of all
goods are moved by
trucks over roads and 85 % of all
persons are transported by
cars,
buses or coaches on roads.
[ Road Transport (Europe) ]
Usage and etymology
Misty road in Australia, entering into a township.
In original usage, a "road" was simply any
pathway fit for
riding. The word “
street,” whose origin is the
Latin ''strata'', was kept for
paved pathways that had been prepared to ease travel in some way. Thus, many "Roman Roads" have the word "street" as part of their name.
[ Street ] Roads are a prerequisite for
road transport of goods on
wheeled
vehicles
.
Words with related usage include,
Avenue,
Boulevard,
Court,
Drive,
Freeway,
Highway,
Lane,
Street,
Turnpike and
Way.
History
That the first pathways were the
trails made by animals has not been universally accepted, arguing that animals do not follow constant paths.
[ Ways of the World: A History of the World's Roads and of the Vehicles that Used Them, , Maxwell G, Lay, Rutgers University Press, , 0813526914 ] Others believe that some roads originated from humans following animals trails.
[1][ Marshalls Heath Nature Reserve ] The
Icknield Way is given as an example of this type road origination were man and animal both selected the same natural line.
[ The Icknield Way Path ] By about
10,000 BC, rough pathways were used by human travelers.
===Historical road construction dating to
4000 BC===
★
Stone paved streets are found in the city of
Ur in the
Middle East dating back to 4000 BC
★
Corduroy road (log road) are found dating to 4,000 BC in
Glastonbury, England ★ The
timber trackway;
Sweet Track causeway in
England, is one of the oldest engineered roads discovered and the oldest timber trackway discovered in
Northern Europe. Built in winter
3807 BC or spring
3806 BC,
tree-ring dating (Dendrochronology) enabled very precise dating. It has been claimed to be the oldest road in the world.
[ The Somerset Levels (the oldest timber trackway discovered in Northern Europe) ]★
Brick paved streets were used in
India as early as
3000 BC ★ In
500 BC,
Darius I the Great started an extensive road system for
Persia (
Iran), including the famous
Royal Road which was one of the finest highways of its time.
[ Royal Road ] The road remained in use after Roman times.
★ In ancient times, transport by
river was far easier and faster than transport by road,
especially considering the cost of road construction and the difference in carrying capacity between
carts and river
barges. A hybrid of road transport and ship transport beginning in about 1740 is the
horse-drawn boat in which the horse follows a cleared path along the river bank.
[ Horseboating ][ Horses and Canals 1760 - 1960 The people & the horses ]
★ From about
312 BC, the
Roman Empire built straight
strong stone
Roman roads throughout Europe and
North Africa, in support of its military campaigns. At its peak the Roman Empire was connected by 29 major roads moving out from
Rome and covering 78,000
kilometers or 52,964
Roman miles of paved roads.
[ Highways: The Location, Design, Construction & Maintenance of Road Pavements, , Coleman A., O'Flaherty, Elsevier, , ISBN 0750650907 ]
★ In the 1600's road construction and maintenance in Britain was traditionally done on a local parish basis.
This resulted in a poor and variable state of roads. To remedy this, the first of the 'Turnpike Trusts' around
1706, to build good roads and collect tolls from passing vehicles. Eventually there were approximately 1,100 Trusts in Britain and some 36,800 km of engineered roads.
The
Rebecca Riots in
Carmarthenshire and
Rhayader from 1839 to 1844 contributed to having a Royal Commission and the demise of the system in 1844.
[ The Rebecca Riots ]
Road transport economics
Main articles: Transport economics
'Transport economics' is a branch of
economics that deals with the allocation of resources within the transport sector and has strong linkages with
civil engineering.
Transport economics differs from some other branches of economics in that the assumption of a spaceless, instantaneous
economy does not hold. People and goods flow over networks at certain speeds. Demands peak. Advanced ticket purchase is often induced by lower fares. The networks themselves may or may not be
competitive. A single trip (the final good from the point-of-view of the consumer) may require bundling the services provided by several firms, agencies and modes.
Although transport systems follow the same
supply and demand theory as other industries, the complications of
network effects and choices between non-similar goods (e.g. car and bus travel) make estimating the demand for transportation facilities difficult. The development of models to estimate the likely choices between the non-similar goods involved in transport decisions "
discrete choice" models led to the development of the important branch of
econometrics, and a
Nobel Prize for
Daniel McFadden.
[2]
In transport,
demand can be measured in numbers of journeys made or in total distance traveled across all journeys (e.g. passenger-kilometres for
public transport or vehicle-kilometres of travel (VKT) for
private transport).
Supply is considered to be a measure of
capacity. The
price of the good (travel) is measured using the
generalised cost of travel, which includes both
money and
time expenditure. The effect of increases in supply (capacity) are of particular interest in transport economics (see
induced demand), as the potential environmental consequences are significant.
Road building and maintenance is an area of economic activity that remains dominated by the
public sector (though often through
private contractors).
[ International Market Research Reports ] Roads (except those on private property not accessible to the general public) are typically paid for by
taxes (often raised through levies on fuel),
[ State and Federal Gasoline Taxes ] though some
public roads, especially
highways are funded by
tolls.
[ International Bridge, Tunnel and Turnpike Association ]
Driving on the right or the left
Main articles: Driving on the left or right
Traffic flows on the right or on the left side of the road depending on the country.
[ Why In Britain Do We Drive On The Left? ] In countries where traffic flows on the right,
traffic signs are mostly on the right side of the road,
roundabouts and
traffic circles go counter-clockwise, and
pedestrians crossing a two-way road should watch out for traffic from the left first.
[ The Rule of the Road: An International Guide to History and Practice, , Peter, Kincaid, Greenwood Press, , ISBN 0-313-25249-1 ] In countries where traffic flows on the left, the reverse is true.
About 34% of the world by
population drive on the left, and 66% keep right. By roadway distances, about 28% drive on the left, and 72% on the right,
[3] even though originally most traffic drove on the left worldwide.
[4]
Construction
Ride-on with articulating-swivel (small machine)
'Road construction' requires the creation of a continuous
right-of-way, overcoming geographic obstacles and having
grades low enough to permit
vehicle or
foot travel.
[ Kitsap County Road Standards 2006 ] (pg15) and may be required to meet standards set by
law[ Washington State County Road Standards ] or official guidelines.
[ Guidelines for rural road design and construction technical specifications ] The process is often begun with the removal of earth and rock by digging or blasting, construction of
embankments,
bridges and
tunnels, and removal of vegetation (this may involve
deforestation) and followed by the laying of
pavement material. A variety of
road building equipment is employed in road building.
[ Road Building Equipment ] [{{cite web | title = Volvo Construction Equipment (Europe} | work = Building the cities, towns, streets, highways and bridges in your neighborhood and in communities around the globe | publisher = Volvo | date = 2007 | url = http://www.volvo.com/constructionequipment/europe/en-gb/work+solutions/government/introduction.htm | format = Web | doi = | accessdate = April 20, 2007 }}]
After
design,
approval,
planning,
legal and
environmental considerations have been addressed alignment of the road is set out by a
surveyor.
[ Roads and surveying ] The
Radii and
gradient are designed and staked out to best suit the natural ground levels and minimize the amount of cut and fill.
Great care is taken to preserve reference
Benchmarks
Roadways are designed and built for primary use by
vehicular and
pedestrian traffic.
Storm drainage and environmental considerations are a major concern.
Erosion and
sediment controls are constructed to prevent detrimental effects. Drainage lines are laid with
sealed joints in the
road easement with runoff
coefficients and characteristics adequate for the
land zoning and storm water system. Drainage systems must be capable of carrying the ultimate design flow from the upstream catchment with approval for the outfall from the appropriate authority to a
watercourse,
creek,
river or the
sea for drainage discharge.
A
Borrow pit (source for obtaining fill, gravel, and rock) and a water source should be located near or in reasonable distance to the road construction site. Approval from
local authorities may be required to
draw water or for
working (crushing and screening) of materials for construction needs. The
top soil and
vegetation is removed from the borrow pit and stockpiled for subsequent
rehabilitation of the extraction area. Side slopes in the excavation area not steeper than one vertical to two horizontal for safety reasons.
Old road surfaces, fences, and buildings may need to be removed before construction can begin.
Trees in the road construction area may be marked for retention. These protected trees should not have the topsoil within the area of the tree's drip line removed and the area should be kept clear of construction material and equipment. Compensation or replacement may be required if a protected tree is damaged. Much of the vegetation maybe
mulched and put aside for use during reinstatement. The
topsoil is usually stripped and stockpiled nearby for rehabilitation of newly constructed embankments along the road. Stumps and roots are removed and holes filled as required before the earthwork begins. Final rehabilitation after road construction is completed will include seeding, planting, watering and other activities to reinstate the area to be consistent with the untouched surrounding areas.
Processes during earthwork include excavation, removal of material to spoil, filling, compacting, construction and trimming. If rock or other unsuitable material is discovered it is removed, moisture content is managed and replaced with standard fill compacted to 90% relative compaction. Generally
blasting of rock is discouraged in the road bed. When a depression must be filled to come up to the road grade the native bed is compacted after the topsoil has been removed. The fill is made by the "compacted layer method" where a layer of fill is spread then compacted to specifications, the process is repeated until the desired grade is reached.
Typical pavement stratum for a heavily traveled road
General
fill material should be free of
organics, meet minimum
California bearing ratio (CBR) results and have a low
plasticity index. Select fill (
sieved) should be composed of
gravel, decomposed
rock or
broken rock below a specified
Particle size and be free of large lumps of
clay.
Sand clay fill may also be used. The road bed must be "proof rolled" after each layer of fill is compacted. If a
roller passes over an area without creating visible deformation or spring the section is deemed to comply.
The completed road way is finished by
paving or left with a gravel or other
natural surface. The
type of road surface is dependent on economic factors and expected usage.
Safety improvements like
Traffic signs,
Crash barriers,
Raised pavement markers, and other forms of
Road surface marking are installed.
Duplication
When a
single carriageway road is converted into
dual carriageway by building a second separate carriageway alongside the first, it is usually referred to as ''duplication''
[5] or ''twinning''. The original carriageway is changed from two-way to become one-way, while the new carriageway is one-way in the opposite direction. In the same way as converting railway lines from
single track to
double track, the new carriageway is not always constructed directly alongside the existing carriageway.
Sometimes, the new carriageway may be constructed along one side of the existing carriageway for some distance, then constructed on the opposite side. When this occurs, the existing carriageway is split and joined to the new sections, with a short section of the old carriageway being torn up and turned into median.
Maintenance
thumb
Like all structures, roads deteriorate over time. Deterioration is primarily due to accumulated damage from vehicles, however environmental effects such as
frost heaves, thermal cracking and oxidation often contribute.
[ ISAP 9th Conference Titles & Abstracts (#09044) ] According to a series of experiments carried out in the late
1950s, called the
AASHO Road Test, it was empirically determined that the effective damage done to the road is roughly proportional to the 4th power of
axle weight.
[ The Motorway Achievement: Frontiers of Knowledge and Practice, , , , Thomas Telford, , ISBN 0727731971 ] A typical tractor-trailer weighing 80,000 pounds with 8,000 pounds on the steer axle and 36,000 pounds on both of the tandem axle groups is expected to do 7,800 times more damage than a passenger vehicle with 2,000 pounds on each axle.
Pavements are designed for an expected
service life or
design life. In some
UK countries the standard design life is 40 years for new
bitumen and
concrete pavement. Maintenance is considered in the whole life cost of the road with service at 10, 20 and 30 year milestones.
[ Highways: The Location, Design, Construction & Maintenance of Road Pavements, , Coleman A., O'Flaherty, Elsevier, , ISBN 0750650907 ] Roads can be and are designed for a variety of lives (8-, 15-, 30-, and 60-year designs). When pavement lasts longer then its intended life, it may have been overbuilt, and the original costs may have been too high. When a pavement fails before its intended design life, the owner may have excessive repair and rehabilitation costs. Many concrete pavements built since the 1950's have significantly outlived their intended design lives.
[ Road Map to the Future ] Some roads like
Chicago, Illinois's "
Wacker Drive", a major two-level viaduct in downtown area are being rebuilt with a designed service life of 100 years.
[ Fly Ash Concrete Design for Chicago’s 100-Year Road Structure ]
Virtually all roads require some form of maintenance before they come to the end of their service life. Maintenance treatments for
asphalt concrete generally include
crack sealing,
surface rejuvenating,
fog sealing,
micro-milling and
thin surfaceings. Thin surfacing preserves, protects and improves the functional condition of the road while reducing the need for routing maintenance, leading to extended service life without increasing structural capacity.
[ Thin Surfacing - Effective Way of Improving Road Safety within Scarce Road Maintenance Budget ]
Terminology
★ 'All-weather road' - Unpaved road that is constructed of a material that does not create mud during rainfall.
★ '
Bollard' - Rigid posts that can be arranged in a line to close a road or path to vehicles above a certain width
★ '
Byway' - Highway over which the public have
Rights of way in the United Kingdom for vehicular and other kinds of traffic, but which is used mainly as footpaths and
bridleways
★ '
Bypass' Road that avoids or "bypasses" a built-up area, town, or village
★ '
Bottleneck' - Section of a road with a carrying capacity substantially below that of other sections of the same road
★ '
Botts' dots' - Non reflective
raised pavement marker used on roads
★ '
Cat's eye' -
reflective raised pavement marker used on roads
★ '
Chicane' - Sequence of tight serpentine curves (usually an S-shape curve or a bus stop) in a roadway
★ '
Chipseal' - Road surface that is cheaper than
asphalt concrete or a
concrete, in the
US it is usually only used on smaller county roads
★ '
Corniche' - Road on the side of a
cliff or
mountain, with the ground rising on one side and falling away on the other
★ '
Curb' - Edge where a raised
pavement/sidewalk/footpath,
road median, or
road shoulder meets an unraised
street or other roadway.
★ '
Curb extension' - (or also kerb extension, bulb-out, nib, elephant ear, curb bulge and blister)
Traffic calming measure, intended to slow the speed of traffic and increase driver awareness, particularly in built-up and residential
neighborhoods.
★ '
Fork' - (literally "fork in the road") Type of
intersection where a road splits
★ '
Guard rail' - Prevents vehicles from veering off the road into oncoming traffic, crashing against solid objects or falling from a road
★ '
Green lane' - (
UK) Unsurfaced road, may be so infrequently used that vegetation colonises freely, hence 'green'. Many green lanes are ancient routes that have existed for millennia, similar to a
Byway
★ '
Interstate Highway System' -
United States System of Interstate and Defense Highways
★ '
Median' - On divided roads, including
expressways,
motorways, or
autobahns, the 'central reservation'
(British English), 'median'
(North American English), 'median strip' (North American English and
Australian English), 'neutral ground' [Louisiana English] or 'central nature strip' (Australian English) is the area which separates opposing
lanes of
traffic
★ '
Mountain pass' - Lower point that allows easier access through a range of mountains
★ '
Milestone' - One of a series of numbered markers placed along a road at regular intervals, showing the distance to destinations.
★ '
Pedestrian crossing' - Designated point on a road at which some means are employed to assist pedestrians wishing to cross safely
★ '
Private highway' - Highway owned and operated for profit by
private industry
★ '
Private road' - Road owned and maintained by a
private individual,
organization, or
company rather than by a
government
★ '
Public space' - Place where anyone has a right to come without being excluded because of
economic or social conditions
★ '
Ranch road' -
US road which serves to connect
rural and
agricultural areas to
market towns
★ '
Road number' - Often assigned to a stretch of public roadway. The number chosen is often dependent on the
type of road, with numbers differentiating between
interstates,
motorways,
arterial thoroughfares, and so forth
★ '
Road-traffic safety' - Process to reduce the harm (deaths, injuries, and property damage) resulting from crashes of road vehicles traveling on public roads
★ '
Roadworks' - Part or all of the road has to be occupied for work or maintenance relating to the road
★ '
Shoulder' - Reserved area by the verge of a road, generally it is kept clear of all traffic
★ '
State highway' - Road numbered by the
state, falling below numbered national highways (like
U.S. Routes) in the hierarchy ''OR'' A road maintained by the state, including nationally-numbered highways
★ '
Traffic calming' - Set of strategies used by
urban planners and
traffic engineers which aim to slow down or reduce
traffic, thereby improving safety for
pedestrians and
bicyclists as well as improving the environment for residents
★ '
Traffic light' - also known as a 'traffic signal', 'stop light', 'stop-and-go lights', 'robot' or 'semaphore', is a signaling device positioned at a road intersection,
pedestrian crossing, or other location in order to indicate when it is safe to cross a road
★ '
United States Numbered Highways' - Often called U.S. Routes or U.S. Highways is an integrated system of roads and highways in the United States numbered within a nationwide grid
See also
★
Design Manual for Roads and Bridges
★
Inca road system
★
Line source
★
List of roads and highways
★
Road movie
★
Roadway air dispersion model
★
Roadway noise
★
Towing
★
Trade route
★
Corpse roads
References
1. Environment and Planning B: Planning and Design 2001, volume 28 (Self-organizing pedestrian movement), , , , , ,
2. The Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel 2000
3. Which side of the road do they drive on?
4. Why do some countries drive on the right and others on the left?
5. Glossary: Princes Highway, Traralgon Bypass - Planning Assessment Report at The State of Victoria
External links
★
The Post-Roads of Europe 1781 Map
★
National Alliance Against Tolls
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