Introduction

Construction of road or highway are affecting the natural environment in a

various way. Human life condition is enhanced by construction of road or highway,

since road transportation helping people to travel and communicate from one place

to another. In this modern age, construction of new road is a must since city are

developing and increasing size year by year until the effect of road construction can

be seen everywhere. Road construction creating an long term impacts to

environment such as noise pollution, water pollution, air pollution, erosion or failure

of slope due to construction of road at hill side, heat island and many more.

This report is based on the road and environmental issues occurred at

University Malaysia Sabah (UMS). UMS has a big area and it need it’s own highway

or road system for student transportation to go from one faculty to another faculty.

UMS has a systematic road drainage system that help in order to sustain the

environment.

Picture shows UMS map and the grey line is the road system.

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ROADWAY NOISE POLLUTION

Noise is one of the most obvious impacts of daily road use. However, its effects are

often given lower priority because they are rarely visible and are difficult to quantify

monetarily. It is therefore important to understand how road noise comes to exceed

acceptable levels, and what can be done to prevent or reduce its affects.

Roadway noise is caused by some of the following variables: speed of vehicles,

braking, driver behavior and construction and maintenance activity.

EXMAPLE OF ROAD NOISE

The sound from engine and exhaust, stopping during traffic jam and during braking

is the cause of roadway noise. Driver behavior where they play music very loud,

using vehicle horn and sudden braking.

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Construction and maintenance generally require heavy machine, thus contribute

annoying sound to the environment

IMPACT

Chronic exposure of noise can affect human in varying degrees, physiologically and

psychologically. Chronic noise exposure is the source of annoyance, communicating

problems and leads to high stress level. This can affect the human health issue such

as hearing problem. Constant exposure to noise causes sleeping disorder leading to

body fatigue, stress and aggressive behavior. These cases can later turn into more

severe and chronic health issue. Studies suggest that noises can also lead to

cardiovascular issue, high intensity noises cause high blood pressure and increases

in heart rate as it disrupts the normal blood flow.Roadway noises also affect the

wildlife to cross the road because they are afraid. As a result, road became a barrier

for animal travel route.

SCALE OF IMPACT

A well and maintained road are less noisy compared to cracked and damaged road

surfaces. Roadside with vegetation absorb noise while for reflecting concrete or

asphalt do not.In roadway geometry, if receptors are at the same level of

pavement, they audible nuisance are much higher. To keep the receptors out of the

impact zone, they should be at below pavement level or at higher level. This can be

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illustrated in the figure below.

Environmental factors also play a role in producing noise. Temperature and

humidity determine air density, which in turn affects the propagation of sound

waves.

Downwind sites are generally exposed to greater noise levels than are sites upwind

of roads.

In areas with low ambient noise levels, the noise from a new road development will

generally be more noticeable than a similar noise level would be in an environment

with higher ambient noise levels.

If the receptor is much closer to the road, the more the noise they received.

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In traffic stream, as the number of traffic increased, noise level also increased.

Noise are much greater in stop and go traffic. Noise level also increase when

speeding. All of this are caused by the type of vehicles, vehicles maintenance,

number of vehicles and constancy of flow.

NOISE MEASUREMENT

It is measured in unit of dB(decibels). A sonometer is used to measure the existing

noise level.

The figure below shows the scale level of sound in particular area.

SOLUTION

1. For vehicle, the noise can be reduced in designing of vehicle in selecting the

engine system, exhaust system and vehicle maintenance.

2. On - going road maintenance is necessary as to damage and cracked

pavement cause noise.

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3. Road designer must avoid steep slope and sharp to reduce the action of

braking.

4. A noise barrier can be used to reduce noise. A noise barrier must be high

enough and block the view of road. A barrier has only little good in hillside or

a high rise building.

5. Plants or vegetation can help reduce the noise. It must high, wide and dense

enough to reduce as shown below.

Road near Kg AB UMS residential

Water drainage and the environment.

Effective road drainage is vital to road safety. When road drainage systems do not

function well, problems occur, for example:

too much water ponding on the surface, encroaching into driving lanes and

endangering traffic safety;

erosion of drainage ditches;

risk of structural damage or failure of bridge decks;

damage to the aquatic environment from contaminants washing off the road;

and

high costs of maintenance.

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Damage on surface of road.

Though that road drainage is important to the sustainability of the road condition,

drainage also can have negative impact and positive impact on the environment

surrounding.

- Advantages to the environment

a) Reduces erosion on the soil besides the road.

Soil erosion could cause deformation of soil landscape especially on area with little

vegetation and on sloped area. Without water drainage to slow down the flow of

water, soil erosion can easily happen with little warning and can cause massive

damage.

b) Reduces water flow to plants.

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Picture 1 : Crocodile cracking(left) and rutting(right); caused by excess water damaging the subsurface of road.

Drainage prevents excessive water from flowing to plant. High velocity of water flow

will cause small plant to break and dies. Without proper drainage, excessive water

also could flow into planting area where the water will accumulate and cause losses

to farmers and planters alike. Therefore, draining the excess water is essential to

protect plants besides the road from permanent damage.

c) Help direct water to bigger channel or drainage, avoid flash flood.

Flood could be caused by gradual rainfall for an extended period of time. It could

cause millions of damages and could also be life threatening. This is however, can

be countered by early warning by the required authority. Flash flood however, could

happen in just a few hours, due to heavy rainfall. Therefore, it is more rapid and

could cause more damages in properties and human life. Therefore, drainage is

very essential to slow down the build ups of flash flood by directing heavy flow in to

bigger channels. Usually, the big channels are connected to a network of small

drainage to cover a large area.

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Picture 1 : Excessive water could endangered small plant .

Picture 2 : Big drainage to hold big amount of water during rainy days.

d) Provide better protection for road pavement.

As explained before, drainage helps direct water out from the pavement. Without

proper drainage, the pavement would be heavily flooded, causing the water to

infiltrate to the subbase of the pavement, which in turns, softening the subbase.

When this happens, the pavement will deform over time when subjected to loading.

e) Make road safer and protect the drivers.

Accumulation of water on the road surface can also provide danger to the road

users. Water on the road surface wil reduce friction between car tire and the road

surface. Furthermore, water ponding will cause huge splash of water and cause

reduced visibility on the other drivers for a split second. Though only a short time, it

could force human error and cause accident.

- Disadvantages to the environment.

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Picture 4 : Slippery road affect more on heavy vehicle in high speed.

Picture 3 : Water splash cause reduced visibility ob other drivers.

a) Contamination of groundwater souces.

Contamination is highly unlikely caused by drainage. However, it is something that

still will happen and is more damaging if the drainage is nearer to a fresh water

sources. The damage to human live will be more severe as it is harder to detect.

b) Removal of green plant for road alignment.

The alignment of road to achieve 90 degree perpendicularity to the stream below

the road wil cause disturbance in the soil profile of the land. Moreover, trees also

need to be cut down to make way for this purpose, though in small scale, this can

also be considered as disturbing the natural vegetation of the area.

c) Cause unpleasant smell especially on dry season.

One of the common problem with drain is the smell. Smelly drainage could cause

unpleasant feeling towards road users. This is mainly because the drain is blocked

by foreign object that is not supposed to be thrown there. Or, sometimes the

drainage system may be connected with the sewerage systems to reduce cost.

Either way, this can deter road users from using the road and could lead to more

serious problem such as road jam.

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Picture 6 : Drainage system clogged with rubbish, cause smells problem and aesthetically unpleasant to the eye.

Picture 5 : Contaminated drainage water if comes in contact with water sources will cause hazardous damge to human health.

Solution to common problems.

- Provide regular maintenance to the drainage system.

- Build drainage far away from water souces.

- Bring awareness to the public on the importance of maintaining the drainage

system.

- More research on the science of drainage.

SLOPE

A slope is the rise or fall of the land surface. A slope is easy to recognize in a hilly

area. Start climbing from the foot of a hill toward the top, this is called a rising slope

(black arrow). Go downhill; this is a falling slope (white arrow).

Main slope Main slope and cross slope

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The thick arrow indicates the direction of what can be called the main slope; the

thin arrow indicates the direction of the cross slope, the latter crosses the direction

of the main slope.

The main slope and cross slope of an irrigated field

SLOPE FAILURE

A slope failure is a phenomenon that a slope collapses abruptly due to weakened

self-retainability of the earth under the influence of a rainfall or an earthquake.

Because of sudden collapse of slope, many people fail to escape from it if it occurs

near a residential area, thus resulting in a higher rate of fatalities.

Factor of slope failure

1. Gravity

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Gravity acts on all objects on Earth’s surface. Gravity can be divided into two

components for objects resting on sloping surfaces. One component is parallel to

the slope (gs) and one is perpendicular to the slope (gp). On steep slopes (>45

degrees) the component parallel to the slope will be greatest and will act to pull

objects downhill.

2. Properties of Surface

The properties of the surface between the object and the slope (e.g., friction) and

the physical properties of the sliding object itself all contribute to the potential for

mass wasting. The object is more likely to move if friction between the object and

the slope is reduced. In contrast, a slope will be less likely to fail if the cohesion

between the grains in the material is Components of gravity oriented parallel (gs)

and perpendicular (gp) to the slope for gentle and steep slopes5 increased. For

example, no matter how much dry sand is added to a pile, it can never form a slope

that is steeper than 35 degrees inclination. This angle is termed the material’s

angle

of repose. In contrast, by adding a little water, the cohesion between the sand

grains (surface tension) increases dramatically allowing us to sculpt sand castles

with vertical walls. Irregularly shaped objects may form steeper slopes than dry

sand; large angular blocks may have an angle of repose of around 45 degrees. In

contrast, spherical marbles are almost impossible to form into a pile with sloping

sides.

3. Excess of water

The addition of excess water to a slope also is the precursor for a disaster. Not only

does excess water saturate the material and reduce cohesion between grains but

water saturated pore spaces will support the weight of overlying material thus

reducing the effect of friction. Finally, the addition of water may cause instability by

adding weight to a slope.

4. Addition of extra weight

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The addition of extra weight to a slope may be attributed to natural processes (e.g.,

rainfall) but may also be the result of human activity that adds water to the slope

(e.g., leaking septic systems, overzealous irrigation) or adds new structures.

Furthermore, human activity such as logging may remove vegetation that shelters

the slope and provides a network of roots to hold slope material in place.

Slope Failure Processes

• Rock fall occurs when ice wedging loosens angular boulders from rocky cliffs.

• Rockslides occur where sheets of rock move downslope on a planar sliding surface

such as a bedding plane or fracture surface.

• A slump is the downslope movement of material on a curved surface.

• Mudflows and debris flows represent a chaotic mixture of water and

unconsolidated slope materials.

• Arid and temperate areas may be marked by rockfall and rockslides whereas

humid regions will show greater frequency of slumps, mudslides, and debris flows.

1. Rockfall

Rockfall occurs when physical weathering (ice wedging) loosens angular boulders

from rocky cliffs in mountainous terrain. The boulders break off and fall downslope

producing an apron of coarse debris (talus) at the base of the slope. Rockfall is

rarely hazardous because it occurs in relatively isolated locations. However,

activities that place people on or near rock slopes in mountainous areas can

occasionally prove dangerous.

2. Rockslides

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Rockslides occur where a sheets of rock move downslope on a planar sliding

surface. The sliding surface is typically a suitably oriented bedding plane or a

fracture surface.

Rockslides generate relatively thin sheets of rock that are broken into smaller

blocks as they move downslope. The toe of a rockslide is characterized by a jumbled

collection of blocks, some up to hundreds of meters across, at the base of the slide

plane.

3. Slump

A slump is the downslope movement of material on a curved (concave-upward) slip

surface. Slumping typically involves unconsolidated regolith that becomes saturated

with water. The curved sliding surface results in rotation of overlying slump blocks.

A cliff like scarp is left behind at the head of the slump. Slumps frequently occur in

association with saturated slope material that may be the result of heavy

precipitation or inadvertent human activity.

4. Flows

Sediment flows occur when there is a relatively large volume of water present in a

mixture of coarse and/or fine-grained sediment. Rather than moving downslope as a

coherent mass (slump, rockslide) the material flows downhill as a chaotic mixture.

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Flows are differentiated on the basis of their velocity and the type of sediment

involved. Highly fluid mudflows incorporate fine-grained sediment and typically

follow stream channels. These fast-flowing, highdensity flows are common following

volcanic eruptions producing substantial volumes of volcanic ash. Mudflows

involving volcanic debris are termed lahars.

TO PREVENT SLOPE FAILURE

1. Retaining Wall

Retaining walls are structures designed to restrain soil to unnatural slopes. They are

used to bound soils between two different elevations often in areas of terrain

possessing undesirable slopes or in areas where the landscape needs to be shaped

severely and engineered for more specific purposes like hillside farming or roadway

overpasses. Retaining wall is a structure designed and constructed to resist the

lateral pressure of soil when there is a desired change in ground elevation that

exceeds the angle of repose of the soil.

A basement wall is thus one kind of retaining wall. But the term usually refers to a

cantilever retaining wall, which is a freestanding structure without lateral support at

its top. These are cantilevered from a footing and rise above the grade on one side

to retain a higher level grade on the opposite side. The walls must resist the lateral

pressures generated by loose soils or, in some cases, water pressures.

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Every retaining wall supports a “wedge” of soil. The wedge is defined as the soil

which extends beyond the failure plane of the soil type present at the wall site, and

can be calculated once the soil friction angle is known. As the setback of the wall

increases, the size of the sliding wedge is reduced. This reduction lowers the

pressure on the retaining wall.

The most important consideration in proper design and installation of retaining walls

is to recognize and counteract the tendency of the retained material to move

downslope due to gravity. This creates lateral earth pressure behind the wall which

depends on the angle of internal friction (phi) and the cohesive strength (c) of the

retained material, as well as the direction and magnitude of movement the

retaining structure undergoes.

Lateral earth pressures are zero at the top of the wall and - in homogenous ground -

increase proportionally to a maximum value at the lowest depth. Earth pressures

will push the wall forward or overturn it if not properly addressed. Also,

any groundwater behind the wall that is not dissipated by a drainage system

causes hydrostatic pressure on the wall. The total pressure or thrust may be

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assumed to act at one-third from the lowest depth for lengthwise stretches of

uniform height.

Unless the wall is designed to retain water, It is important to have proper drainage

behind the wall in order to limit the pressure to the wall's design value. Drainage

materials will reduce or eliminate the hydrostatic pressure and improve the stability

of the material behind the wall. Dry stone retaining walls are normally self-draining.

2. Vegetation and slope stability

Vegetation and slope stability are interrelated by the ability of the plant life growing

on slopes to both promote and hinder the stability of the slope. The relationship is a

complex combination of the type of soil, the rainfall regime, the plant species

present, the slope aspect, and the steepness of the slope. Knowledge of the

underlying slope stability as a function of the soil type, its

age, horizon development, compaction, and other impacts is a major underlying

aspect of understanding how vegetation can alter the stability of the slope.

There are four major ways in which vegetation influences slope

stability: wind throwing, the removal of water, mass of vegetation (surcharge), and

mechanical reinforcement of roots.

Wind throw is the toppling of a tree due to the force of the wind, this exposes the

root plate and adjacent soil beneath the tree and influences slope stability. Wind

throw is factor when considering one tree on a slope, however it is of lesser

importance when considering general slope stability for a body of trees as the wind

forces involved represent a smaller percentage of the potential disturbing forces

and the trees which are in the centre of the group will be sheltered by those on the

outside.

Vegetation influences slope stability by removing water through transpiration.

Transpiration is the vaporisation of liquid water contained in plant tissue and the

vapour removal to the air. Water is drawn up from the roots and transported

through the plant up to the leaves.

The major effect of transpiration is the reduction of soil pore water pressures which

counteracts the loss of strength which occurs through wetting, this is most readily

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seen as a loss of moisture around trees. However it is not easy to rely on tree and

shrub roots to remove water from slopes and consequently help ensure slope

stability. The ability to transpire in wet conditions is severely reduced and therefore

any increase in soil strength previously gained in evaporation and transpiration will

be lost or significantly reduced, consequently the effects of transpiration cannot be

taken into account at these times. However it can be assumed that the chance of

slope failure following saturation by storm event or periods of extended rainfall will

be lessened as a result of transpiration. Moreover, although changes in moisture

content will affect the undrained shear strength, the effective shear stress

parameters as commonly used in routine slope stability analysis are not directly

influenced by changing moisture content, although the water pressures (suctions)

used in the analysis will change.

The mass of vegetation is only likely to have an influence on slope stability when

larger trees are growing on the slope. A tree of 30 -50m height is likely to have a

loading of approximately 100 -150kN/m2. The larger trees should be planted at the

toe of the slope with a potential rotational failure as this could increase the factor of

safety by 10%. However if the tree is planted at the top of the slope this could

reduce the factor of safety by 10%. A suggested design vegetation envelope which

shows which type of plant should be grown at each level of the slope.

Each slope stability situation should be considered independently for the vegetation

involved. It is important to remember that transpiration will reduce the weight of

the slope as moisture is lost. This can be significant on slopes of marginal stability.

If larger trees are removed from the toe area of a slope there will be both a

reduction in soil strength due to the loss of evapotranspiration effects and a

reduction in applied loading which may result in temporary suctions in clay soils

which could lead to softening as the available water is drawn in to compensate for

the suction forces. This is similar to the recognised softening of overconsolidated

clays due to the relaxation of overburden pressures when placed in the top layers of

an embankment from deep cutting.

Road shading and environment

While visual obstructions are not the direct target of this objective, this

problem must be considered when applying these strategies. Trees may create

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various types of visual obstructions such as limiting sight distance at intersections,

driveways, and curves. Trees may also block a sign, or other roadside hardware,

and also obstruct the driver's view of pedestrians and other road users. An abrupt

transition from bright sunlight to dense shade or vice versa can be a great safety

hazard. Extreme changes in light can have a devastating effect on the motorists’

visibility and be a direct cause of accidents. Extreme changes in light conditions

should be avoided. A limited amount of shading may be more effective and efficient

for our road maintenance and the environment

Trees planted (or allowed to grow) too closely to a road create several potential

hazards. The most obvious is the fixed-object hazard created when an errant vehicle

runs off the road and strikes a tree. The other hazards caused by trees include

visual obstruction of signs and other roadway users, sight distance obstructions (at

intersections, driveways, and curves), and an overhead hazard to large trucks.

Advantages

1. Shading helps retain road moisture, reducing dust

Figure 1Shading reduce dust

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2. Reduces growth of colonizer plant species

3. A limited amount of shading may be more effective and efficient for our road

maintenance and the environment.

4. As s shelter to pedestrians who that walking at the side of the road.

Figure 2 Shaded tree as a shelter to pedestrian

Disadvantages

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1. Shading retains road moisture, promoting unsafe conditions such as ponding.

Figure 3 Ponding of water under the shaded area

2. Shading also reduces visibility and limits the “clear zone,” again affecting

safety.

Figure 4 Limit the sight distance

Maintenance

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Colonizer trees can threaten the roadway safety and recreate shade. These

colonizer trees then become extremely high maintenance roadside plants. In many

cases the plants we most want to remove are the plants most encouraged by our

efforts. This creates the need to mow and trim in increasingly frequent cycles. When

doing roadside trimming and tree removal, dead, dying, unstable and damage tree

need to remove. They will become hazard to road user.

Large tree limbs growing above the roadway may create overhead-object

hazards. The FHWA recommends a clearance of 9 feet above the roadway and/or

sidewalk for trimming the lower limbs. Applying this minimum height provides

sufficient room for signs on the shoulders as well. There may be different height

requirements defined by local ordinances, or by the needs of the roadway. A route

open to large trucks may need a height greater than 14 feet. On roads with higher

volumes of large trucks, the truck traffic may maintain this height by "default

trimming" the branches when they are small, as the trucks hit them when they pass

under the tree. This is a situation to be avoided, and where "default trimming" does

not happen, the limbs may grow large enough to create an overhead object hazard,

and cause a significant amount of property damage to the tree and the truck, if not

trimmed in a timely manner.

Picture below show shaded road at road to UMS PEAK

Conclusion

Road and environmental are different things but affecting one to another. To

improve human life condition, construction of road is a must. Environment can be

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sustain with proper and good road construction or maintenance. UMS road design

with proper ditch, road crown and drainage system helps in conserving the nature

and also giving a longer road life. Through proper road maintenance there won’t be

any issues come up regarding the destruction of environment by the road. It’s a

must for an engineer to construct a road that don’t give much effect to

environment.

Reference

1. Definition of slope. Available at:

http://www.fao.org/docrep/r4082e/r4082e04.htm ( Accesses on 31 May

2014) 10.00pm

2. slope failure. Available at:http://www.sabo-int.org/dott/slope.html

( Accesed on 1 june 2014) 1 am

3. Factor of slope failure, slope failure process. Available at :

http://www.kean.edu/~csmart/Observing/12.%20Slope%20failure

%20and%20landslides.pdf (Accesed on 1 jun 2014) 1 am

4. retaining wall. Available at: http://en.wikipedia.org/wiki/Retaining_wall

( Accessed on 1 june 2014) 9.41 am

5. vegetation and slope stability. Available at:

http://en.wikipedia.org/wiki/Vegetation_and_slope_stability (1 Accessed on

june 2014) 9.41 am

6. http://safety.transportation.org/htmlguides/trees/app01.htm

7. Jones P., consult L. (n.d) Highway drainage.

8. McGuire T.M. & Morrall J.F (1999), Strategic highway improvement to

minimize environmental impacts within the Canadian rocky mountain

National Parks.Canada

9. Tsunokawa K. & Hoban C. (n.d). Roads and Environments

10.Wilson S. (n.d), Sustainable drainage. Cambridge City Council

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