Cubic parabola is a type of

LEVEL 6 BENG CIVIL ENGINEERING

TRANSPORT INFTRASTUCTURE ENGINEERING

COURSEWORK ASSESSMENT

Tasks: You are expected to answer to the questions provided in the following assignment. The assignment must be written/typed as the answer of the questions. Any hand-written note will not be assessed. You can also analyse the data by means of graphs and tables in MS Excel software. Please bear in mind that similarity will be strictly checked by the module leader/examiner and Turnitin software tool once you submit your assignment.

Assessment criteria/Marking scheme: They are based on the breakdown provided in the module study guide (MSG).

Submission: This assignment must be submitted to Turnitin before the deadline. You will find a link to the Turnitin Assignment from the Assessments area of the Blackboard course menu. You will need to ensure that your assessment is uploaded as a single document, and in the correct format (e.g., a Word document or PDF – the acceptable file formats are displayed on screen when you come to submit via Turnitin). You should refer to Module Study Guide for further information and regulation of submission through Turnitin. Also, please note that similarity will be strictly checked by Turnitin software tool once you submit your report.

1. A divided rural multilane highway is required to cope with an AADT of 30 000 veh/day. A 60 mi/h design speed is chosen with lanes of a standard 3.65 m width and obstructions within 0.61 m on both sides of roadway. The terrain is mountainous and the percentages for the various heavy vehicle types are as follows: PT = 8%, PB = 7% and PR = 7%. The Driver Population is “Ideal”. The Peak Hour Factor (PHF) is 0.85 and the Directional Factor D is estimated at 0.55. If the highway is required to maintain LOS C and it is to be designed to cope with the 30th highest hourly volume during the year, calculate the followings:

1.1. The number of lanes in each direction.

1.2. If the client requires a reduction of 1 lane per direction, demonstrate what is the best solution to adopt between a) extending the “Distance to obstruction from travelled edge” up to 1.22 m, or b) rearranging the whole highway over a type of terrain from “mountainous” to “rolling”.

1.3. Discuss potential solution(s) other than those at point 1.2, that may reduce the number of lanes for the concerning highway (hint: keep constant the following parameters: divided multi-lane arrangement; AADT = 30000 veh/day; Design Speed = 60 mi/h; lane width = 3.65 m; “ideal” driver population; PHF = 0.85; D = 0.55).

2. A transition curve is required for a dual carriageway road with a design speed vdesign = 27.78 m/s. The bearings of the two straights in question are 24° and 53°. Assuming a value of 0.40 m/s3 for C and a superelevation e = 7.0%, identify the followings:

2.1. The transition length, L.

2.2. The shift, S.

2.3. The length along the tangent required from the intersection point to the start of the transition, IT̅ .

2.4. The form of the cubic parabola and the coordinates of the point at which the transition becomes the circular arc of radius R.

2.5. Plot the transition curve assuming a proper offset for the largest x or y coordinate.

2.6. What is the optimum value of “rate of change of radial acceleration” Copt that meets the criterion L ≤ Lmax with the least difference (L = length of the transition curve; Lmax = maximum length of transition curve recommended by the UK Standards)? (hint: round up Copt to the 2nd decimal digit).

2.7. Plot a graph of C (x axis) against L (y axis) and critically comment on the results considering the followings:

2.7.1. Same initial design speed and superelevation conditions (i.e., vdesign = 27.78 m/s and e = 7.0%).

2.7.2. Same initial design speed with a superelevation e = 5.0% (i.e., vdesign = 27.78 m/s and e = 5.0%). 2.7.3. Same initial superelevation with a design speed = 23.61 m/s

(i.e., vdesign = 23.61 m/s and e = 7.0%).

Hint: range of variation of C for plotting the graphs is to be considered from

C = 0.02 m/s3 to C = Copt, case by case, using steps of 0.02 m/s3 for C.