EG7032 Highway & Railway Engineering Assignment Brief | UOEL

EG7032 Project Brief:

You are an engineer working for an engineering consultancy who has been commissioned by a transport authority to provide technical assistance related to the following highway and railway problems:

1. Highway maintenance, assessment, and methods (20%)

1 a). A site investigation was conducted on an existing highway pavement located in a subtropical temperature environment. Sections of the highway have experienced premature distresses such as that shown in Figure Q1.1. Overloading is a known problem in the area. Results of gradation tests conducted on samples taken within selected sections of the road revealed the particle size distribution shown in Table Q1.1 and average air voids of 2.5%. Falling Weight Deflectometer (FWD) deflection data indicated that the base can be considered marginal. Based on the given information, write a short report indicating what you think are the likely causes of the premature failure. Clearly describe your approach assuming the pavements were designed using UK pavement mix design standards. Clearly state all your assumptions.

1 b). A section of the pavement was overlaid with 50 mm of asphalt concrete (AC) binder course and 40 mm of AC wearing course. The pavement developed rutting (average rut depth of 20 mm) during the first summer after construction. Which AC course has likely contributed to the development of rutting? What is the most suitable way to determine the layer causing the problem?

Table Q1.1 FWD sensor readings for pavement section. Note deflections is in mils 

2. Highway Pavement Analysis and Design (20%)

Figure Q2.1 shows a cross-section of an existing pavement located in a city in the Northern hemisphere. Use the information provided to answer the following questions.

1a) For the pavement structure shown in Figure Q2.1, determine the effective thickness based on the information given. Use the Asphalt Institute approach in the determination of the effective thickness.
1b) Assuming pavement has a subgrade stiffness of 10,000 psi (69 MPa), Determine the thickness of overlay required to carry anticipated of 3.0 msa using the effective thickness approach.
1c) For the same pavement as in the above, a series of 10 deflection measurements by Benkelman beam were made on the pavement during a critical period when the pavement temperature was 13°C. The measured deflections in inches are as shown in

Figure Q2.1. Details of existing pavement.

Figure Q2.2. Determine the representative rebound deflection, the design rebound deflection, and the required overlay thickness. Assume the stiffness of the asphalt overlay is 500,000 psi.

Figure Q2.2. Benkelman beam deflections.

3. Track structure analysis & design (25%)

1. Describe, with illustrations, four types of trackbed structures in common use indicating some of their advantages and disadvantages (10%)
2. For the track structure shown in Figure Q3.1, it desired to replace the concrete ties with wooden ties. Determine the reduction in service life as a result of the change from wooden ties to concrete ties. Clearly state all assumptions made. You can use any layer elastic analysis software of your choice but it is recommended to us Kentrack software as discussed in class. (15%)

Figure Q3.1. Structure for a ballasted trackbed.

4. Environmental impacts (25%)

1. Briefly discuss the mechanism of ballast system failure. Use well-labelled sketches to illustrate your answer (10%).
2. Discuss the implications of ballast failure (5%).
3. Discuss the main differences between the aggregates for railway ballast and aggregates for highway granular base construction. (5%)
4. Discuss three factors that are critical to aggregates used for construction track ballast high speed rail applications. (5%)