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EAT 360

HIGHWAY & TRANSPORTATION

ENGINEERING

BY MDM LIYANA AHMAD SOFRI

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Transportation is essential for a nation’s

development and growth.In both the public and private sector,

opportunities for engineering careers intransportation are exciting and rewarding.

Elements are constantly being added to theworld’s highway, rail, airport, and mass transit

systems, and new techniques are being appliedfor operating and maintaining the systems safely

and economically.

Many organizations and agencies exist to plan,design, build, operate, and maintain the nation’s

transportationsystem.8/6/2014copyright 2006 www.brainybetty.com 2

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Transportation Engineering

Characteristics of the driver, pedestrian,vehicle and the road

Traffic engineering studies

Traffic light design

Highway Safety

Fundamental principles of traffic flow

The transportation planning process

Forecasting travel demand

Highway surveys and location

Geometric Design of Highway Facilities

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• The four main components of the highwaymode of transportation are the driver, thepedestrian, the vehicle, and the road.

• To provide efficient and safe highway

transportation, a knowledge of thecharacteristics and limitations of each ofthese components is essential.

• It is also important to be aware of theinterrelationships that exist among thesecomponents in order to determine theeffects, if any, that they have on each other.

1.2 Traffic Studies

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Their characteristics are also of primaryimportance when traffic engineeringmeasures such as traffic control devicesare to be used in the highway mode.

Knowing average limitations may notalways be adequate; it may be necessary

to sometimes obtain information on thefull range of limitations.


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Similarly, a wide range of vehicles, from compact

cars to trucks, have been designed. The maximumacceleration, turning radius, and ability to climbgrades differ considerably among differentvehicles.

The road therefore must be designed toaccommodate a wide range of vehicle

characteristics while at the same time allowinguse by drivers and pedestrians with a wide rangeof physical and psychological characteristics.


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1.3: Driver Characteristics

Satu masalah yang menghadapi lalu lintas dan pengangkutan

jurutera apabila mereka menganggap ciri-ciri pemandu dalamperjalanan reka bentuk kemahiran yang berbeza-beza dankebolehan persepsi pemandu di lebuh raya, ditunjukkan olehpelbagai kebolehan untuk mendengar, melihat, menilai, dan

bertindak balas terhadap maklumat.

Kajian telah menunjukkan bahawa kebolehan ini jugamungkin berbeza dalam seseorang individu di bawah

keadaan yang berbeza, seperti pengaruh alkohol, keletihan,dan masa hari.

Oleh itu, adalah penting bahawa kriteria yang digunakanuntuk tujuan reka bentuk supaya sesuai dengan

kemampuan dan batasan kebanyakan pemandu di lebuhraya


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1.3.1: The Human Response Process

Tindakan yang diambil oleh pemandu pada hasil jalandari penilaian mereka dan reaksi kepada maklumatyang mereka perolehi daripada rangsangan tertentuyang mereka melihat atau mendengar.

Walau bagaimanapun, penilaian dan tindak balas

perlu dilakukan dalam masa yang singkat, keranamaklumat yang diterima di sepanjang lebuh rayaadalah sentiasa berubah.

Ia telah dicadangkan bahawa kebanyakan maklumatyang diterima oleh pemandu adalah visual, yang

membayangkan bahawa kemampuan untuk melihatadalah kepentingan asas dalam tugas memandu.

Oleh itu, adalah penting bahawa lebuh raya dan lalulintas jurutera mempunyai pengetahuan asas persepsi

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a) Visual Acuity

Ketajaman penglihatan adalah keupayaan untuk melihat

butiran halus objek.

Ia boleh diwakili oleh sudut visual, yang

adalah salingan corak butiran yang palingkecil dalam beberapa minit lengkok yang

boleh diselesaikan.


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b) Peripheral Vision.

Visi periferal adalah keupayaan orang ramai untuk melihat

objek di luar kon penglihatan jelas. Walaupun objek boleh

dilihat di dalam kawasan berkenaan, butiran dan warna tidak

jelas.

Umur juga mempengaruhi penglihatan periferal. Sebagai contoh,

pada kira-kira usia 60 tahun, perubahan yang ketara berlaku

dalam penglihatan periferal seseorang.


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Masa yang diperlukan olehseseorang untuk pulih daripadakesan-kesan silau selepas lulussumber cahaya dikenali sebagai

pemulihan silau.

Kajian telah menunjukkanbahawa masa ini adalah kira-kira

3 saat apabila bergerak darigelap kepada cahaya dan boleh

menjadi 6 saat atau lebih apabilabergerak dari cahaya kepada

gelap.

Visi Silau adalah amat pentingsemasa memandu malam; ia

menyumbang kepada masalah

berkhidmat orang tua, yangmelihat lebih kurang pada waktu

malam.

Kesan silau boleh dikurangkandengan mengurangkan

kecerahan sistem lampu dan

dengan meningkatkan kecerahanlatar belakang dalam bidang

memandu pandangan.


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e) Depth Perception.

Persepsi kedalaman mempengaruhi keupayaanseseorang untuk menganggarkan kelajuan dan jarak. Ia

adalah penting di lebuh raya dua lorong semasa lulus

manuver, apabila kemalangan kepala mungkin

disebabkan oleh kekurangan penghakiman yang betul

kelajuan dan jarak.

Harus diingat, bagaimanapun, bahawa mata manusia tidak begitubaik pada menganggar nilai mutlak kelajuan, jarak, saiz, dan

pecutan. Inilah sebabnya mengapa alat-alat kawalan lalu lintas

adalah standard dalam saiz, bentuk, dan warna.

Standardisasi bukan sahaja membantu dalam anggaran jarak tetapi jugamembantu pemandu buta warna untuk mengenal pasti tanda-tanda.


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1.4 Perception-reaction Process

1. Perception: the driver

sees a control device,

warning sign, or object onthe road.

2. Identification: the

driver identifies the

object or control device

and thus understands

the stimulus.

3. Emotion: the driver

decides what action to

take in response to the

stimulus; for example, to

step on the brake pedal, topass, to swerve, or tochange lanes.

4. Reaction or volition: the

driver actually executes theaction decided on duringthe emotion sub-process.


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Distance Traveled During Perception-Reaction Time

•A driver with a perception-reaction time

of 2.5 sec is driving at 65 km/h when sheobserves that an accident has blocked theroad ahead. Determine the distance thevehicle would move before the driver

could activate the brakes. The vehicle willcontinue to move at 65 km/h during theperception-reaction time of 2.5 sec.


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• Pedestrian characteristics relevant to trafficand highway engineering practice includethose of the driver

• Pedestrian characteristics may influence thedesign and location of pedestrian controldevices.

• Such control devices include special

pedestrian signals, safety zones and islandsat intersections, pedestrian underpasses,elevated walkways, and crosswalks.

1.5 PEDESTRIANS CHARACTERISTICS


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Apart from visual and hearing characteristics, walkingcharacteristics play a major part in the design of some of these

controls. For example, the design of an all-red phase, whichpermits pedestrians to cross an intersection with heavy traffic,requires knowledge of the walking speeds of pedestrians.

Observations of pedestrian movements have indicated thatwalking speeds vary between 0.9 and 2.4 m/sec.

Significant differences have also been observed between male

and female walking speeds. At intersections, the mean malewalking speed has been determined to be 1.5 m /sec, and forfemales, 1.4 m/sec. A more conservative value of 1.22 m/sec isnormally used for design purposes.


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Consideration also should be given to thecharacteristics of handicapped pedestrians, such as

the blind. Studies have shown that accidentsinvolving blind pedestrians can be reduced byinstalling special signals.

The blind pedestrian can turn the signal to a redphase by using a special key, which also rings a bell,indicating to the pedestrian that it is safe to cross.

Ramps are also now being provided at intersectioncurbs to facilitate the crossing of the intersection bythe occupant of a wheelchair.


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• Criteria for the geometric design ofhighways are partly based on the static,kinematic, and dynamic characteristics ofvehicles.

• Static characteristics include the weight andsize of the vehicle,

• Kinematic characteristics involve themotion of the vehicle without consideringthe forces that cause the motion.

• Dynamic characteristics involve the forcethat that cause the motion of the vehicle

1.6 VEHICLES CHARACTERISTICS


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The characteristics of the design vehicle are thenused to determine criteria for geometric design,intersection design, and sight-distance

requirements.

It is essential that design criteria take into

account the characteristics of different types ofvehicles.


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The characteristics of thehighway discussed in this section

are related to stopping andpassing because these have amore direct relationship to thecharacteristics of the driver andthe vehicle discussed earlier.


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• Sight distance is the length of the roadwaya driver can see ahead at any particulartime.

• The sight distance available at each pointof the highway must be such that, when adriver is traveling at the highway’s designspeed, adequate time is given after an

object is observed in the vehicle’s path tomake the necessary evasive maneuverswithout colliding with the object.

Sight distance


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• The stopping sight distance (SSD), for designpurposes, is usually taken as the minimum sightdistance required for a driver to stop a vehicle afterseeing an object in the vehicle’s path without hittingthat object.

• This distance is the sum of the distance traveledduring perception-reaction time and the distancetraveled during braking.

Stopping Sight Distance


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• The passing sight distance is the minimumsight distance required on a two-lane, twoway highway that will permit a driver tocomplete a passing maneuver without

colliding with an opposing vehicle andwithout cutting off the passed vehicle.

• The passing sight distance will also allow

the driver to successfully abort the passingmaneuver (that is, return to the right lanebehind the vehicle being passed) if he orshe so desires.

Passing Sight Distance

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The minimum passing sight distance is the total of four components :

d1 distance traversed during perception-reaction time and during initialacceleration to the point where the passing vehicle just enters the left lane

d2 distance traveled during the time the passing vehicle is traveling in theleft lane

d3 distance between the passing vehicle and the opposing vehicle at the

end of the passing maneuver

d4 distance moved by the opposing vehicle during two thirds of the timethe passing vehicle is in the left lane (usually taken to be 2/3 d2)

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