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THE CLO4 was comprised of this major topic:
Module 4: Analysis of Roads
This module is all about the application of queuing theory to analyze the flow of traffic.
Study Guide # 1
a. Introduction to Transportation Planning & Engineering
b. Transportation as a System
c. Urban Transportation Planning Concepts
Study Guide # 2
a. Philippine Transportation System
b. Transportation Safety & Economics
c. Transportation Policy Analysis and Planning/Technical Tour
Study Guide # 3: Introduction to Travel Demand Forecasting (Classic Four- Step Forecasting Model)
Study Guide # 4: Traffic Impact Assessment
Module 3: Basic Service Requirements of Highway
This module covers the different traffic studies to conduct level of service analysis on highways.
MAJOR CAUSE OF PAVEMENT FAILURES:
1. Rutting due to high variation in ambient temperature
2. Uncontrolled heavy axle load
3. Inadequate stability
4. Loss of binding action
5. Poor Design and Fabrication
DIFFERENT TYPES OF CRACKS:
a. Fatigue Cracking – is sometimes called alligator’s skin.
Possible Causes: Weakened Base or Subgrade, Not enough pavement thickness, Poor Drainage Remedy: Full Depth Patch
b. Block Cracking - is a series of large (typically one foot or more), rectangular cracks on an asphalt pavement’s surface.
Possible Causes: Shrinkage of asphalt due to temperature changes, placing of mix too dry, poor choice of asphalt binder
Remedy: Cracks < 0.5in or less can be sealed with bitumen to prevent water seepage. For wider cracks, layer be replaced with an overlay.
c. Longitudinal Cracking – these occur parallel to the center of the asphalt or laydown direction.
Possible Causes: Shrinkage of asphalt, poorly constructed joint, reflective cracking, poor paver operation
Remedy: Cracks < 0.5in or less can be sealed with bitumen to prevent water seepage. For wider cracks, layer be replaced with an overlay.
One concrete application of this fourth-course learning objective would be in terms of VOLUME STUDY. In particular, the Average Annual Daily Traffic (AADT). The terminology refers to the average of 24-hour counts collected every day of the year. In this particular work, we were tasked to determine the AADT on a rural primary road that has the volume distribution characteristics shown in the tables that the class discussed. At first, it was quite challenging because I don't know how to find the date, but in the end, I was able to find out which is which and be able to realize that it's just easy to find the data given that there are many formulas to be familiarized.
d. Transverse Cracking – these occur parallel to the center of the asphalt or laydown direction.
Possible Causes: Shrinkage of asphalt, poorly constructed joint, reflective cracking, poor paver operation
Remedy: Cracks < 0.5in or less can be sealed with bitumen to prevent water seepage. For wider cracks, layer be replaced with an overlay.
e. Edge Cracking – these are longitudinal cracks that occur within a foot or two of each other on the outer edges of the asphalt.
Possible Causes: poor drainage on sides or pavement, lack of support on the edge of pavement, heavy vegetation along the side of the pavement, heavy traffic
Remedy: provide proper drainage, remove vegetation, small gaps be filled to make pavement impermeable
f. Reflection Cracking – happens because of asphalt pavement overlays that have been placed over a pavement structure that has been cracked or jointed.
Possible Causes: movement of old pavement
Remedy: Cracks < 0.5in or less can be sealed with bitumen to prevent water seepage. For wider cracks, layer be replaced with an overlay.
g. Slippage Cracks – crescent shaped cracks
Possible Causes: weak asphalt mix or poo bonds between pavement layers
Remedy: partial or full depth patch]
h. Depressions – also called bird baths; these are pavement areas that have lower elevations than surrounding area
Possible Causes: not enough or not uniform compaction
Remedy: removal of layer and an overlay Less severe depression can be rectified by thin surface patch
i. Rutting – longitudinal depressions in the wheel tracks or in the direction of the traffic flow.
Possible Causes: insufficient pavement thickness, lack of compaction, poor grade of bitumen, moisture infiltration
Remedy: underlying layers be removed and replace with good quality base sub-base material following asphalt layer as well.
As for the basic stream parameters, it was discussed that there are 3 fundamental parameters of the traffic flow. One of which is the speed. Speed is considered as a quality measurement of travel as the drivers and passengers will be concerned more about the speed of the journey than the design aspects of the traffic. It is defined as the rate of motion in distance per unit of time. Another thing is the flow. There are practically two ways of counting the number of vehicles on a road. One is flow or volume, which is defined as the number of vehicles that pass a point on a highway or a given lane or direction of a highway during a specific time interval. And lastly, the density. Density is defined as the number of vehicles occupying a given length of highway or lane and is generally expressed as vehicles per km.
Another topic is regarding the basic flow model. I learned that traffic flow models are based on the assumption that there is some relation between the distance between vehicles and their velocity. This means that in relation to the first topic, this basic flow model needs the fundamental parameters to work effectively and efficiently.
In application, the queue theory would be applied to the so-called QUEUE SPILLBACK (Azlan & Rohani, 2018). If a queue spills back through a diverge or an intersection it can delay vehicles that do not even use the bottleneck, i. e., vehicles that leave the queue downstream of that bottleneck and create no delay for other users. Users of the link with the bottleneck are generally not delayed further, regardless of the physical length of the queue.
It is evident that I developed basic traffic stream parameters and models, traffic flow models, and apply the queuing theory.
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