10 Jul Civil engineering report
School of Civil and Environmental Engineering Term 2, 2019 CVEN3031 CIVIL AND ENVIRONMENTAL ENGINEERING PRACTICE PROJECT BRIEF: AN ASSESSMENT OF THE IMPACTS OF SYDNEY’S SOUTH-EAST LIGHT RAIL This document contains most of the necessary information for the group project in this course. Read this document thoroughly to understand the deliverables. This project is to be completed in groups of 5 students. Context The CBD and South East Light Rail is a new light rail network for Sydney, currently under construction. The 12km route will feature 19 stops, extending from Circular Quay along George Street to Central Station, through Surry Hills to Moore Park, then to Kensington and Kingsford via Anzac Parade and Randwick via Alison Road and High Street (Figure 1). It is expected that a combined bus and light rail network will significantly improve public transport access to major sporting and entertainment facilities at Moore Park and Randwick, along with the University of NSW, TAFE and health precincts1. Figure 1 – Model network for the group project 1 https://sydneylightrail.transport.nsw.gov.au/ 1 Your project group has been commissioned to prepare a Transport Impact Assessment (TIA) of Sydney’s CBD and South-East light rail. A transport network focussed on the Eastern Suburbs of Sydney (Figure 1) has been supplied for this assessment. Traffic microsimulation of the supplied network is to be undertaken, using AIMSUN software. This project is to be completed in two stages: 1. Base Model development 2. Scenario Testing and Analysis. 1. Development of the Base Model Modelling of the Existing Conditions (Base Model) is essential for evaluating the impacts generated by a proposed scenario (i.e. An upgrade or a change to the network). The base model is required for two key reasons: • To enable accurate verification, calibration and validation of model parameters to ensure that the model reflects current traffic conditions and provides rationalised and logical projections of future performance. • To create a benchmark, which can be used to measure the effectiveness of the proposed options/designs. Information and Data for the Project • The network file you are to import is given on Moodle. • You are only to consider cars and buses in the base model. • The simulation will run for one hour (AM peak, from 8:00AM to 9:00AM) and will require a 15minute warm-up period. • Majority of the traffic signals have already been coded. However, there are a few that need to be coded by your project group. The signal timing and movement data for those signalised intersections will be provided in a separate document on Moodle. • Most of the bus routes have already been coded in the network provided to you on Moodle. There are a few routes that need to be coded. More details are provided in a separate document. O-D matrix estimation and model calibration An Origin-Destination (O-D) matrix describes user movement throughout a defined area. An O-D matrix is necessary for traffic simulation models and for planning and managing transportation systems. 2 However, the exact values of the O-D matrix are difficult to measure. Traditionally, O-D matrices are “estimated” based on household travel surveys. There have been several research studies in recent years, which try to estimate the O-D matrices based on traffic volume data obtained through physical infrastructure such as loop detectors, sensors, etc. However, such infrastructure requires substantial investments. Your project group is required to estimate the O-D matrix for the network based on the observed travel times. The total demand (car only) of the network in one hour is 12,765 cars. However, this value is allowed to be changed by up to ±5%. The travel times between different O-D pairs is shown in Table 1. Estimate the O-D matrix (the number of trips from one centroid to another) based on these travel times. Consider using the percentages of trip productions and attractions that you reported in the first assignment. Most of the research studies mentioned above use advanced mathematical methods to estimate the O-D matrices, which are beyond the scope of the course. Therefore, use trial-andimprovement approach to estimate the O-D matrix. The O-D matrix estimation procedure is deemed satisfactory when at least 85% of the O-D pairs’ (0.85*42 =36) simulated travel times are within ±30% of the observed travel time2. Table 1 Real-world travel time matrix (in mins) O\D 1 2 3 4 5 6 7 1 0 9 3 8 7 1 7 2 3 0 4 10 9 10 5 3 2 9 0 11 9 7 6 4 8 14 12 0 5 6 12 5 8 13 8 1 0 6 11 6 7 14 5 5 4 0 10 7 4 7 6 10 7 10 0 Validation of the model The real-world traffic flow obtained from loop detectors should be used to validate the simulation model. Use the GEH statistic to determine the validity of the model. • M= Model traffic volume • C = Real-world traffic volume 2 Note: that the calibration procedure and criteria in this project is slightly different from the RMS guidelines. This has been done to meet the time constraints of the course. 3 Table 2 Real-world traffic flow (veh/hr) Detector ID 1 2 3 4 5 Location Anzac Pde near Barker St (towards city) Anzac Pde near Todman Av (outbound from city) Anzac Pde near Dacey Av (towards city) Alison Rd near Anzac Pde (towards city) High St near Botany St Flow (veh/hr) 1,540 1,730 870 2,680 205 The model is deemed validated if the average GEH of all the above locations is less than 10. The O-D matrix needs to be adjusted further if the criteria is not satisfied3. Stability Analysis (determine the number of replications needed) Models must be assessed under several seed values to ensure the stability of the model. Once the model is calibrated and validated based on one replication, create 4 more replications with different seed values (check the lecture slides for random seed values). Total Travel Time (TTT) of the network should be used to determine the stability of the model. The number of replications needed to ensure statistical model stability (internal consistency) is determined by: • ݖఈൗଶ is the desired confidence multiplier for a two-tailed normal distribution (1.96 for 95% CI) • σ is the standard deviation of TTT from 5 replications • ∆ is the acceptable precision (decimal) of the mean – 5% of the mean TTT of 5 replications. Report the outputs of the base model Report all the significant metrics of the base model based on the original seed value. These metrics should be decided by your group based on engineering judgement and/or past reports. 3 In real-life projects, following the validation step, calibration needs to be evaluated again as it is an iterative process. The model is considered fully calibrated and validated only after satisfying both the criteria. However, in this project, calibration is not required after validating the model. 4 2. Scenario Testing Scenario analysis is the second (and final) stage of the group project. It involves integrating light rail transit (LRT) with the existing base model. There will be several aspects which need to be accounted for, within the simulation model. i. Changes to the existing road network a. Adding lanes (sections) for light rail b. Removing the normal traffic lanes ii. Adjusting traffic signals and phases a. Will traffic signals be the same as before? iii. Adjusting bus routes a. How will the frequencies of the existing bus routes change? b. How will the dwell times change? c. Will any/some bus routes be changed? iv. Modelling light rail a. What are the dimensions of the light rail? b. Where should the LRT stops be located? c. What should be the frequency of LRT? d. What should be the dwell times? v. Adjusting O-D matrix a. Will the introduction of LRT induce a reduction in number of car trips? vi. Performance analysis, i.e. comparing the network performance with the base case a. Total System Travel Time b. Are there any new congestion/choke points? What happened to choke points from the base model? c. Is there a change in specific O-D travel times? d. Has LRT reduced emissions in the network? e. How to convert the benefits to monetary values? All the above questions should be answered based on engineering judgement and previous literature. 5 Overview of Tasks Table 3 Checklist of tasks for the group project S.No. Stages 1 Project report 1: Base model 2 Project report 2: Scenario analysis Checklist o Tables and figures o Succinct and simplified reporting Structure o Project Context and Background o Study Scope o Limitations and Assumptions (engineering judgement and/or references) o Datasets and Usage o Coding and network finalisation (signals and bus routes) o Calibration o Validation o Stability analysis o Calculations o Discussion of outputs o Conclusions o References and Appendices (If required) o Tables and figures o Succinct and simplified reporting Structure o Accounting for LRT: considerations and assumptions (engineering judgement and/or references) o Datasets and Usage o Coding and network refinement o Stability analysis o Calculations o Discussion and comparison of outputs (base and scenario) o Innovation o Conclusions o References and Appendices (If required) Plagiarism Beware! An assignment that includes plagiarised material will receive a 0% Fail, and students who plagiarise may fail the course. Students who plagiarise are also liable to disciplinary action, including exclusion from enrolment. Plagiarism is the use of another person’s work or ideas as if they were your own. When it is necessary or desirable to use other people’s material you should adequately acknowledge whose words or ideas they are and where you found them (giving the complete reference details, including page number(s)). The Learning Centre provides further information on what constitutes Plagiarism at: https://student.unsw.edu.au/plagiarism 6 …
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