Assignment 2: Transport Modelling and Operations Due: 7 October 2022
This is an individual assignment
Please answer the following questions and present your work in a report format clearly including your name and student ID on the cover page.
Submit a PDF of your report into the Assignment Activity shown on the UTS Canvas page for 49102 by 7 October 2022 (11:59PM).
Late Submission Penalties: (10% will be deducted per day) Ensure you present all working out clearly and legibly
Problem 1: Estimating Saturation Flow Rate of an Intersection (20 marks)
Traffic approaches a signalised intersection in a single lane that is 4.0m wide. The traffic flow arriving at the approach is 849 vehicles per hour of which:
- 65% are cars going straight through the intersection
- 10% are cars turning left at the intersection
- 15% are trucks going straight through the intersection
- 10% are trucks turning left at the intersection.
The approach of the intersection is on an uphill gradient of 3% and there is a large amount of pedestrian activity associated with a nearby bus stop. Due to these factors, the environment around the intersection provides poor conditions for vehicle movement on both the approach and departure of the intersection, and left turning movements are considered to be restricted. Calculate the saturation flow for the approach.
Problem 2: Intersection Analysis and Design – Comparing Options (60 marks)
An unsignalised T-intersection at the corner of Main Road and Myna Street has been experiencing considerable delays and excessive queuing on one of its approaches during the afternoon peak period.
A traffic survey was conducted during the afternoon peak period, giving the following volumes:
Table 1 – Existing intersection volumes (veh/h)
|Myna Street||1) Left Turn||525|
|2) Right Turn||158|
|Main Road East||3) Left Turn||105|
|Main Road West||5) Through||840|
|6) Right Turn||420|
Figure 1 – Movement diagram of Main Road/Myna Street
Each approach has two lanes, each movement operates in its own lane and there are no shared lanes. In order to address the excessive queuing problem, a proposal has been received to change the intersection control to a signalised intersection. The assumptions and properties of each design are as follows.
· Unsignalised Intersection Assumptions and Properties
- Design values for critical gap and follow up gap for the left turning manoeuvre from Myna Street are 4 seconds and 2 seconds respectively, and for right turning manoeuvres from either Main Road West or Myna Street are 5 seconds and 3 seconds respectively. The queuing service rates (practical capacities) are assumed to equal 90 per cent of the corresponding theoretical absorption capacities.
- Remember that right turning traffic from Main Road West must give way to all traffic from Main Road East.
· Signalised Intersection Assumptions and Properties
- You can assume that if the intersection were to be reconfigured as a signalised intersection, the existing lane discipline would be maintained. That is: each approach has two lanes, each movement operates in its own lane and there are no shared lanes.
- Saturation Flows are assumed to be 1700 veh/h for through movements, 1670 veh/h for protected right turn movements, and 1570 veh/h for left turn movements.
- The intersection would operate as a three phase timing plan, with leading protected right turns from the east approach (Movement 6 in Figure 2 below).
- Inter-green times and minimum displayed green times are assumed to be 4 seconds and 7 seconds respectively for all movements, resulting in lost times and minimum effective green times also of 4 seconds and 7 seconds respectively.
Figure 2 – Phasing diagram for Main Road/Myna Street
You have been asked to compare the performance of the intersection under the current (unsignalised) control with it operating as a signalised intersection.
To do this, you should:
a) Calculate the proportions of vehicles that have to stop, for all six manoeuvres considering both configurations. (18 marks)
- Calculate the average delays per vehicle (average time in the ‘system’), for the six movements, for the three approach roads, and for the intersection as a whole, considering both configurations. (18 marks)
c) Calculate the 95th percentile queue lengths (exceeded only 5% of the time), for the six approaches in the unsignalised configuration.
d) Calculate the maximum queue lengths, for the six approaches in the signalised configuration. (6 marks)
- Having analysed the performance of the intersection under three alternative configurations, it is important to be able to clearly convey your findings to a technically-literate but time-poor audience. You are also asked to provide a concise 2-page (maximum length) summary report of your findings, including tables and graphs comparing the performance of the intersection under both configurations. This report would identify the initial problem which prompted this investigation, and would include several paragraphs describing the findings and some recommendations for what to do with the intersection.
Problem 3: Pedestrian Crossing Analysis (20 marks)
The intersection that you analysed in Problem 2 would have a pedestrian crossing across Myna Street (the southern approach of the T-intersection). This pedestrian crossing would have to cross over two approach lanes and two exit lanes, each having a width of 3.5 metres, as well as a median strip of width 1 metre. The crossing would be 2 metres wide, and the traffic survey gave results indicating there would be a maximum of 10 pedestrians waiting to cross in any signal cycle.
a) Calculate the pedestrian crossing time using the method described in the lecture material for Block 2. (12 marks)
- How does this crossing time compare to the minimum green time assumed when calculating the signal timings, and do we need to adjust the timings to account for this calculated crossing time? (8 marks)
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