Bài giảng Tiếng Anh Chuyên ngành giao thông Đại học Công Nghệ GTVT (UTT)Unit 2part 1

In construction grade staking: - blue tops 2x2x6 to 12 inch stakes mark the level of finish grade; - red tops 2x2x6 to 12 inch stakes mark the level of sub-grade; Blue top Grade stake R

Unit 2 CONSTRUCTION OF ROADS AND BRIDGES

1 VOCABULARY BUILDING

Highway Surveys

1 In pairs, guess the meaning of the following terms.

A man standing at the benchmark point

Aggrega te Benchma

rk

Surveyors take soil boring sample using a drill rig or a hand auger

Right-of-way and centerline stakes

Marking and setting slope stakes

Slope stake

Soil boring sample

cL

6’

F

6 0

cL

Front

Centerline Stakes

cL

4.0

C

4 0

26 0

Marking and placement of slope stakes

cL

1:1

26.0 16.0 6.0 4.0

In construction grade staking:

- blue tops (2x2x6 to 12 inch stakes) mark the level of finish

grade;

- red tops (2x2x6 to 12 inch stakes) mark the level of

sub-grade;

Blue top (Grade stake)

Red top (Grade stake)

CL

CL

Typical arrangement of various stakes on a road section (final grading)

Match the terms with definitions.

Benchmark  

indicate required grade elevations to the construction crews During the final grading

stage of construction, hubs called “blue

tops” are used in lieu of stakes

Soil boring

samples  

Stone and gravel of various sizes which compose the major portion of the surfacing material The sand or pebbles added to cement

in making concrete

Centerline

stakes  

are used to indicate the inside edge of the roadway shoulders These stakes are set opposite each center-line stake

Shoulder

a fixed reference point that is used in the surveying process to accurately measure elevations

mark the intersection offside slopes with the natural ground surface They indicate the earthwork limits on each side of the center line

Right-of-way

indicate the exact center of the roadway construction

Grade stakes

are taken by drilling down into the ground to determine the soil composition before or during construction

Aggregate   indicate the legal right of passage or corridor

and outmost bounds of construction

2 READING

a Have you ever visited a highway construction site? What can you see on

a highway construction site?

Highway Construction Procedures

By Amanda Holden

Two words can cause sighs of defeat and exasperation among travelers: road

construction Yet, while road construction seems inconvenient and

troublesome, in truth it benefits the public By building and repairing roadways, people may travel long distances with relative ease, a feat that would become near impossible without passable roads Road construction in the U.S follows a standard set of procedures for longevity and usability of the future roadway

b Read the text and order the paragraphs 1-6.

A Levelling and Paving

Workers place blue stakes every 10-20 meters and begin to level the ground to meet the pre-mapped elevation benchmarks With the "blue tops" on the surface, contractors perform a final touch to the earth or dirt road Then workers begin to lay

an aggregate, or a rocky, densely-packed substance, to the levelled ground as a base, followed later by asphalt and other surface dressing materials

B Ground Assessment

Once the surveyors have completed mapping the area, they must next assess the ground for road suitability Workers take soil samples from boreholes using

a drill rig or hand auger, with a minimum of 15 samples (borings) every kilometer These samples stretch out to 30 meters on either side of the new highway and once analyzed, lead to a classification of the area's soil profile Swamps, lakes, rivers and other wetlands require more surveys and assessments, not only to determine the ecological impact of a new roadway but also to determine suitability

C Maintenance

Over time, the new road will experience damage due to weather and use Chips will develop in the pavement from freezing water, encroaching plants, snow chains and more Sometimes existing roadways need expansion to handle an increasing amount

of traffic Roads undergo repaving, repainting and more to stay in operation

Surveying

Before construction ever begins, extensive mapping and topographic survey takes place Surveyors map the entire area to pinpoint where the new road will sit Once complete, adjacent homes are mapped and if necessary, bought out through the government's right of eminent domain, which occurs if the property falls within the new road's right-of-way Surveyors note the topography of the surrounding area, such as mountains, streams and lakes, and place the new road accordingly Benchmarks are mapped every 250-300 meters for the entire

length, referencing elevation in comparison to sea level and signifying the future preferred elevation of the road

E Finishing Touches

Workers apply paint to the finished road and begin work on slopes and ditch bottoms

to try and prevent erosion They place stakes for various erosion control materials, such as straw and rock Workers apply paint to the new road to guide the users and identify traveledway lanes Final measurements will determine the quality of the road construction job, as well as whether the road meets legally-required standards These factors play into the contractor's final pay

Once the government has completed all the mapping, property acquisition and soil studies, actual groundwork can begin Workers place survey posts every 25-30 meters on the new road's centerline and at the right of way limits and removal of trees and bush begins After workers have cleared the trees and bush, they place construction stakes on the centerline, slope stakes, stakes for culverts, storm drains and curbs

c Put the following words into the six correct categories above

mapping survey topography construction stakes painting alignment paving erosion control soil survey

benchmarks repaving cross sections property corners

swamp soundings right of way acquisition centerline reestablishment repainting tree and bush removal

Mapping

and

Surveyin

Mapping

survey

d Read again and answer the questions

1 What do surveyors do before construction begins?

2 How far is it between two benchmarks?

3 How many soil samples are taken every kilometer?

4 Why do wetlands require more surveys and assessments?

5 What do workers do after tree and bush removal?

6 When do constructors perform the final touch to the dirt road?

7 What do the workers do before paving asphalt?

8 What do workers do in the finishing touches?

9 Why do the roads require maintenance?

3 LISTENING

Watch a video about Asphalt Paving Inspection and complete the

following note.

ASPHALT PAVING INSPECTION

Compaction

- Compaction makes the pavement dense

- Rolling must achieve the desired (1) , smoothness and surface texture.

- 3 phases in rolling: Breakdown, intermediate, (2) .

- Typical arrangement of vehicles:

+ Steel wheel vibratory roller in breakdown.

+ Pneumatic roller in (3) .

+ Static roller in final/finish rolling.

Inspecting tips

- Watch each roller at (4) direction.

- Rollers should process in a (5) _line

- Rollers should work at (6) speed

- On super-elevation, rolling should start at (7) _ side

- Longitude (8) _ should always roll first.

-

ASPHALT PAVING INSPECTION

Compaction

- Compaction makes the pavement dense

- Rolling must achieve the desired (1) , smoothness and surface texture.

- 3 phases in rolling: Breakdown, intermediate, (2) .

- Typical arrangement of vehicles:

+ Steel wheel vibratory roller in breakdown.

+ Pneumatic roller in (3) .

+ Static roller in final/finish rolling.

Inspecting tips

- Watch each roller at (4) direction.

- Rollers should process in a (5) _line

- Rollers should work at (6) speed

- On super-elevation, rolling should start at (7) _ side

- Longitude (8) _ should always roll first.

-

4 SPEAKING

In groups of four, discuss the characteristics of asphalt pavement and PCC

(Portland Cement Concrete) pavement using comparative adjectives.

Students A: List 5 advantages of Asphalt Pavement over PCC Pavement

Students B: List 5 advantages of PCC Pavement over Asphalt Pavement

Characteristics of Asphalt Pavement and PCC

Pavement

(Source: Guidelines on Expressways in Japan – Kosoku Doro Chosaika)

Design

Resistance

to

Deformatio

n and

Abrasion

Less resistant against deformation, causing rutting.

Less resistant to

generated with studded tires

Deformation such as

observed.

Highly resistant to abrasion in general.

Noise and

Vibration

joints, and noise due to harsh or rough texture are sometimes problems

Brightness

of Surface Reflectance of the surface is lower than

PCC, which causes difficulty in driving through tunnels

Lighter after dark or inside tunnels

Evenness of

Surface Normally better than PCC

Restrictive

Conditions

in

Constructio

construction work, and production rate is

Large number of construction equipment items, which inevitably tends to produce

n normally higher restriction as below.

Production rate is also lower.

- Subgrade preparation should be successively done.

- Structures like bridges and culverts should be fewer in number.

provided with asphalt wearing course.

Maintenanc

e and

Rehabilitati

on

Possible and easy with

employed, so that PCC

on soft ground should be avoided.

Cost

Analysis Initial cost is cheaper, but frequent repair is

required and total cost over 20 years or so is sometimes higher.

Initial cost is higher Reconstruction is more expensive