1,721,152 research outputs found
Management of Competing Demands on Urban Freight Corridors
No full textThis paper compares the performance under various scenarios of an urban traffic corridor section subjected to a range of vehicle types.\ud
A micro-simulation-based model of the corridor was developed from first principles to stochastically assign characteristics and headways for each vehicle and then to track each vehicle as it moved along the corridor. Kinematic behaviour of the different vehicle types (ranging from passenger cars through to B-doubles) were obtained from GPS data collected during a series of chase car surveys on an urban arterial freight route in suburban Brisbane. The car-following and lane-selection algorithms used by the model are outlined in the paper. In order to account for the variability between runs, multiple simulation runs were typically conducted using different random number seeds. Corridor performance was reported in terms of intersection capacity and delays as well as travel speeds and stop rates for each vehicle type.\ud
The performance of the corridor was found to be sensitive to traffic control measures including the speed limit and traffic signal controller settings such as cycle time and progression design speed. A range of freight policy scenarios were examined, including the effects of increasing freight volumes, freight vehicle mode choice, and vehicle type-specific lane restrictions. Some policies having the potential to improve corridor traffic performance and freight efficiency were able to be identified
Making the train : re-conceptualising accessibility for intra-urban rail travel
No full textAustralian authorities have set ambitious policy objectives to shift Australia’s current transport profile of heavy reliance on private motor cars to sustainable modes. Improving accessibility of public transport is a central component of that objective. Past studies on accessibility to public transport focus on walking time and/or waiting time. However, travellers’ perceptions of the interface leg journeys may depend not only on these direct and tangible factors but also on social and psychological factors. This paper extends previous research that identified five salient perspectives of rail access by means of a statement sorting activity and cluster analysis with a small sample of rail passengers in three Australian cities (Zuniga et al, 2013). This study collects a new data set including 144 responses from Brisbane and Melbourne to an online survey made up of a Likert-scaled statement sorting exercise and questionnaire. It employs factor analysis to examine the statement rankings and uncovers seven underlying factors in the exploratory manner, i.e., station, safety, access, transfer, service attitude, traveler’s physical activity levels, and environmental concern. Respondents from groups stratified by rail use frequency are compared in terms of their scores of those factors. Findings from this study indicate a need to re-conceptualize accessibility to intra-urban rail travel in agreement with current policy agenda, and to target behavioral intervention to multiple dimensions of accessibility influencing passengers’ travel choices. Arguments in this paper are not limited to intra-urban rail transit, but may also be relevant to public transport in general
Microscopic modelling of freeway operations
No full textFreeways are divided roadways designed to facilitate the uninterrupted movement of motor vehicles. However, many freeways now experience demand flows in excess of capacity, leading to recurrent congestion. The Highway Capacity Manual (TRB, 1994) uses empirical macroscopic relationships between speed, flow and density to quantify freeway operations and performance. Capacity may be predicted as the maximum uncongested flow achievable.\ud
Although they are effective tools for design and analysis, macroscopic models lack an understanding of the nature of processes taking place in the system.\ud
Szwed and Smith (1972, 1974) and Makigami and Matsuo (1990) have shown that microscopic modelling is also applicable to freeway operations. Such models facilitate an understanding of the processes whilst providing for the assessment of performance, through measures of capacity and delay. However, these models are limited to only a few circumstances.\ud
The aim of this study was to produce more comprehensive and practical microscopic models. These models were required to accurately portray the mechanisms of freeway operations at the specific locations under consideration.\ud
The models needed to be able to be calibrated using data acquired at these locations. The output of the models needed to be able to be validated with data acquired at these sites. Therefore, the outputs should be truly descriptive of the performance of the facility. A theoretical basis needed to underlie the form of these models, rather than empiricism, which is the case for the macroscopic models currently used. And the models needed to be adaptable to variable operating conditions, so that they may be applied, where possible, to other similar systems and facilities.\ud
It was not possible to produce a stand-alone model which is applicable to all facilities and locations, in this single study, however the scene has been set for the application of the models to a much broader range of operating conditions.\ud
Opportunities for further development of the models were identified, and procedures provided for the calibration and validation of the models to a wide range of conditions. The models developed, do however, have limitations in their applicability. Only uncongested operations were studied and represented.\ud
Driver behaviour in Brisbane was applied to the models. Different mechanisms are likely in other locations due to variability in road rules and driving cultures.\ud
Not all manoeuvres evident were modelled. Some unusual manoeuvres were considered unwarranted to model. However the models developed contain the principal processes of freeway operations, merging and lane changing. Gap acceptance theory was applied to these critical operations to assess freeway performance.\ud
Gap acceptance theory was found to be applicable to merging, however the major stream, the kerb lane traffic, exercises only a limited priority over the minor stream, the on-ramp traffic. Theory was established to account for this activity. Kerb lane drivers were also found to change to the median lane where possible, to assist coincident mergers. The net limited priority model accounts for this by predicting a reduced major stream flow rate, which excludes lane changers. Cowan's M3 model as calibrated for both streams. On-ramp and total upstream flow are required as input. Relationships between proportion of headways greater than 1 s and flow differed for on-ramps where traffic leaves signalised intersections and unsignalised intersections. Constant departure onramp metering was also modelled. Minimum follow-on times of 1 to 1.2 s were calibrated. Critical gaps were shown to lie between the minimum follow-on time, and the sum of the minimum follow-on time and the 1 s minimum headway.\ud
Limited priority capacity and other boundary relationships were established by Troutbeck (1995). The minimum average minor stream delay and corresponding proportion of drivers delayed were quantified theoretically in this study. A simulation model was constructed to predict intermediate minor and major stream delays across all minor and major stream flows. Pseudo-empirical relationships were established to predict average delays. Major stream average delays are limited to 0.5 s, insignificant compared with minor stream delay, which reach infinity at capacity.\ud
Minor stream delays were shown to be less when unsignalised intersections are located upstream of on-ramps than signalised intersections, and less still when ramp metering is installed. Smaller delays correspond to improved merge area performance. A more tangible performance measure, the distribution of distances required to merge, was established by including design speeds. This distribution can be measured to validate the model. Merging probabilities can be predicted for given taper lengths, a most useful performance measure. This\ud
model was also shown to be applicable to lane changing. Tolerable limits to\ud
merging probabilities require calibration. From these, practical capacities can be\ud
estimated. Further calibration is required of traffic inputs, critical gap and\ud
minimum follow-on time, for both merging and lane changing. A general\ud
relationship to predict proportion of drivers delayed requires development.\ud
These models can then be used to complement existing macroscopic models to\ud
assess performance, and provide further insight into the nature of operations
Gardens Point campus transport study 2000
No full textThe University Chancellery Office has requested that the School of Civil Engineering undertake pedestrian traffic monitoring surveys prior to, and following commissioning of the Southbank pedestrian/bicycle bridge between Gardens Point and Southbank, in order to ascertain the effects of the new bridge on pedestrian activity across the campus.\ud
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This report presents the scope and design of the survey of transport movement associated with the Gardens Point campus of QUT. This is followed by a summary of the information ascertained from the 15.5 hour survey conducted on Tuesday 19 September 2000, and a brief discussion on the possible impacts of the new bridge
Passenger transmission and productiveness of transit lines with high loads
No full textDeterministic transit capacity analysis applies to planning, design and operational management of urban transit systems. The Transit Capacity and Quality of Service Manual (1) and Vuchic (2, 3) enable transit performance to be quantified and assessed using transit capacity and productive capacity. This paper further defines important productive performance measures of an individual transit service and transit line. Transit work (p-km) captures the transit task performed over distance. Passenger transmission (p-km/h) captures the passenger task delivered by service at speed. Transit productiveness (p-km/h) captures transit work performed over time. These measures are useful to operators in understanding their services’ or systems’ capabilities and passenger quality of service. This paper accounts for variability in utilized demand by passengers along a line and high passenger load conditions where passenger pass-up delay occurs. A hypothetical case study of an individual bus service’s operation demonstrates the usefulness of passenger transmission in comparing existing and growth scenarios. A hypothetical case study of a bus line’s operation during a peak hour window demonstrates the theory’s usefulness in examining the contribution of individual services to line productive performance. Scenarios may be assessed using this theory to benchmark or compare lines and segments, conditions, or consider improvements
AITPM national newsletter president's report March 2010
No full textAs a tertiary educator, business is now starting to\ud
heat up for my colleagues and me as Semester\ud
1 commences. I’d like to take this opportunity to\ud
wish all readers who are students or academic\ud
staff, whether sessional or full-time, a successful\ud
year of teaching to, and learning more about,\ud
the transport profession. I’d also like to note\ud
the important role played by our AITPM National\ud
Council Education Coordinator, being fulfilled by\ud
Victoria Branch President Mr Tony Fitts, along\ud
with all of our branches’ Education Coordinators
Critical gap estimation by numerical and statistical highest likelihood search
No full textMany traffic situations require drivers to cross or merge into a stream having higher priority. Gap acceptance theory enables us to model such processes to analyse traffic operation. This discussion demonstrated that numerical search fine tuned by statistical analysis can be used to determine the most likely critical gap for a sample of drivers, based on their largest rejected gap and accepted gap. This method shares some common features with the Maximum Likelihood Estimation technique (Troutbeck 1992) but lends itself well to contemporary analysis tools such as spreadsheet and is particularly analytically transparent. This method is considered not to bias estimation of critical gap due to very small rejected gaps or very large rejected gaps. However, it requires a sufficiently large sample that there is reasonable representation of largest rejected gap/accepted gap pairs within a fairly narrow highest likelihood search band
Moving multi-combination vehicles on Brisbane's urban arterial roads
No full textResearchers at Queensland University of Technology (Brisbane, Australia) are studying the impacts of multi-combination vehicles, such as the popular 25m B-double, on arterial road trafc operation. A PhD project is examining the impact of MCVs on trafc progression along the Brisbane Urban Corridor, which includes Riawena and Kessells Roads, while a Masters project is examining the lateral position impacts on a section of the Gateway Motorway
Evaluation of Freight Corridor Mode Performance: \ud Brisbane - Cairns Corridor Freight Movement Analysis
No full textThis report provides an analysis of freight movements on the Brisbane - Cairns corridor as an activity within the project Evaluation of Freight Corridor Mode Performance. It follows on from the lead activity which produced the document Evaluation of Freight Corridor Mode Performance: A Literature Review (Bunker, 2001).\ud
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The project hypothesis is that the transport planning and freight transport decision making processes could be more well informed by developing a model that represents in detail the process of mode selection for corridor freight movements, using key performance indicators. The overall aim is to develop a framework for such a model and is to include a freight corridor in Queensland as a case study. The corridor that was selected is Brisbane - Cairns.\ud
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The purposes of this analysis of freight movements on the Brisbane - Cairns corridor are to become familiar with the attributes of the corridor, and to gain an understanding of how each freight mode is currently being used in the line haul freight task along the corridor. This will provide a basis for investigating the nature and values of specific freight mode choice determinants and performance indicators for this corridor developed earlier in the study, through consultation with the parties involved in the decision making process.\ud
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This examination of freight flows on the Brisbane - Cairns corridor has demonstrated that Brisbane is the focus of freight movements along the corridor. In the northbound direction, this is attributed to regional areas' reliance on Brisbane for the supply of goods. In the southbound direction, Brisbane, although less pronounced, is also the principle destination for freight originating in the regional areas. The directional split is even south of Bundaberg, while the northbound split is dominant on links further north, suggesting a strong reliance by northern centres for inwards goods movement from Brisbane.\ud
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The northbound task is well spread amongst road, rail and sea along the length of the corridor. Road is on most links the dominant mode in the southbound direction. A substantial empty backhaul exists in the southbound direction across all modes, except for road south of Bundaberg.\ud
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It is evident from the data that in the northbound direction, sea dominates, but is generally restricted to the bulk freight task, which is primarily petroleum distribution from Brisbane refineries to regional areas. In the southbound direction, sea carries very little intra-state freight, aside from the bulk movement of bauxite between Weipa and Gladstone for refining, but dominates the movement of bulk freight (primary produce) to the southern states.\ud
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Air is restricted in both directions to a very small volume of freight, which is expected to be high value, rapid transit freight.\ud
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The balance of the corridor freight task in both directions is distributed between road and rail. It is apparent from the data that on an overall corridor basis there is strong competition between these modes in moving all freight types, including bulk, non-bulk containerable and non-bulk non-containerable. Road generally carries more freight than rail, although the task is relatively even in both directions between Rockhampton and Townsville. On a distance basis, the mode share to road decreases marginally with distance while that to rail increases marginally. However, road is still dominant even on the longest distance movements between Brisbane and Cairns.\ud
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Closer examination of the data suggests that for bulk freight and non-bulk non-containerable freight, on a movement by movement basis, one mode is likely to tend to dominate, due to a natural advantage for that particular movement. This may be termed the "right mode for the task" effect, which is associated with parameters of the individual task. However, it is difficult to ascertain the reasons for mode selection in the non-bulk containerable freight segment.\ud
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With the modal competition evident, this freight corridor has diverse attributes that enable a useful investigation into the customer service provider/mode selection process for individual freight tasks. This will provide further insight into the modal distribution evident on the corridor
AITPM national newsletter President's report June 2010
No full textThis is my penultimate report as National\ud
President of the Australian Institute of Traffic\ud
Planning and Management, Inc. As an\ud
academic, I would like to take this opportunity\ud
to raise some issues and challenges I see in\ud
transport professional education in Australia. My\ud
general view is that the transport profession has\ud
until recently been less conspicuous to others as\ud
an identifiable discipline. This is both a blessing\ud
and somewhat of a curse. People mostly enter,\ud
or sometimes fall into, the transport profession\ud
having taken a degree in civil engineering,\ud
other engineering, urban and regional planning,\ud
economics, industrial psychology, business,\ud
followed by the less obvious disciplines. This\ud
order is probably about relative to the proportion\ud
of members’ background qualifications in our\ud
ranks too. However, once a graduate destined\ud
to become a transport professional has spent\ud
about five years or so out of the academic\ud
estuary, they tend to specialise in an area that\ud
cannot necessarily be easily correlated to the\ud
well known courses I have rattled off above.\ud
I can say from experience that it is not out of\ud
the question to see SIDRA models having been\ud
prepared by a transport professional who did\ud
not take traffic engineering as part of a civil\ud
engineering degree. So I see a couple of key\ud
challenges for the transport profession, which\ud
happens to be represented by a number of\ud
bodies, with our AITPM perhaps being the peak\ud
body, into the future
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