Aquaplaning assessment and mitigation in flat terrains

1.1 Aims The aim of this project is to research and analyse potential solutions to reduce the risk of aquaplaning on roads in flat terrain (particularly on transitions of superelevated curves) and determine whether the current design standards used in Queensland are appropriate. 1.2 Objectives The objectives of this research come under two broad categories. The first of which is to determine whether the current methodology and standard requirements used in Queensland for assessing aquaplaning potential are appropriate. Upon completion of this research project, a register of the methodologies and standards used internationally will be compiled. The underlying principles, assumptions and calculation bases of each method will be presented and compared with those of the Australian method. Advice regarding the suitability of the Australian method will be presented and recommendations for improvement will be given if applicable. The second objective of this research is to identify solutions to reduce aquaplaning potential and where they are most applicable. Several internationally used solutions to this problem will be investigated and evaluated to determine the advantages and disadvantages of each. Recommendations will also be provided regarding the applicability of each solution to the context of Southern Queensland

The anatomy of exhumed river-channel belts: Bedform to belt‐scale river kinematics of the Ruby Ranch Member, Cretaceous Cedar Mountain Formation, Utah, USA

Many published interpretations of ancient fluvial systems have relied on observations of extensive outcrops of thick successions. This paper, in contrast, demonstrates that a regional understanding of palaeoriver kinematics, depositional setting and sedimentation rates can be interpreted from local sedimentological measurements of bedform and barform strata. Dune and bar strata, channel planform geometry and bed topography are measured within exhumed fluvial strata exposed as ridges in the Ruby Ranch Member of the Cretaceous Cedar Mountain Formation, Utah, USA. The ridges are composed of lithified stacked channel belts, representing at least five or six re‐occupations of a single‐strand channel. Lateral sections reveal well‐preserved barforms constructed of subaqueous dune cross‐sets. The topography of palaeobarforms is preserved along the top surface of the outcrops. Comparisons of the channel‐belt centreline to local palaeotransport directions indicate that channel planform geometry was preserved through the re‐occupations, rather than being obscured by lateral migration. Rapid avulsions preserved the state of the active channel bed and its individual bars at the time of abandonment. Inferred minimum sedimentation durations for the preserved elements, inferred from cross‐set thickness distributions and assumed bedform migration rates, vary within a belt from one to ten days. Using only these local sedimentological measurements, the depositional setting is interpreted as a fluvial megafan, given the similarity in river kinematics. This paper provides a systematic methodology for the future synthesis of vertical and planview data, including the drone‐equipped 2020 Mars Rover mission, to exhumed fluvial and deltaic strata

OPTIMIZATION OF STATION LOCATIONS AND TRACK ALIGNMENTS FOR RAIL TRANSIT LINES

Designing urban rail transit systems is a complex problem, which involves the determination of station locations, track geometry, right-of-way type, and various other system characteristics. The existing studies overlook the complex interactions between railway alignments and station locations in a practical design process. This study proposes a comprehensive methodology that helps transit planners to concurrently optimize station locations and track alignments for an urban rail transit line. The modeling framework resolves the essential trade-off between an economically efficient system with low initial and operation cost and an effective system that provides convenient service for the public. The proposed method accounts for various geometric requirements and real-world design constraints for track alignment and stations plans. This method integrates a genetic algorithm (GA) for optimization with comprehensive evaluation of various important measures of effectiveness based on processing Geographical Information System (GIS) data. The base model designs the track alignment through a sequence of preset stations. Detailed assumptions and formulations are presented for geometric requirements, design constraints, and evaluation criteria. Three extensions of the base model are proposed. The first extension explicitly incorporates vehicle dynamics in the design of track alignments, with the objective of better balancing the initial construction cost with the operation and user costs recurring throughout the system's life cycle. In the second extension, an integrated optimization model of rail transit station locations and track alignment is formulated for situations in which the locations of major stations are not preset. The concurrent optimization model searches through additional decision variables for station locations and station types, estimate rail transit demand, and incorporates demand and station cost in the evaluation framework. The third extension considers the existing road network when selecting sections of the alignment. Special algorithms are developed to allow the optimized alignment to take advantage of links in an existing network for construction cost reduction, and to account for disturbances of roadway traffic at highway/rail crossings. Numerical results show that these extensions have significantly enhanced the applicability of the proposed optimization methodology in concurrently selecting rail transit station locations and generating track alignment

Identification, Calculation and Warning of Horizontal Curves for Low-volume Two-lane Roadways Using Smartphone Sensors

Smartphones and other portable personal devices that integrate global positioning systems, Bluetooth Low Energy, and advanced computing technologies have become more accessible due to affordable prices, product innovation, and people’s desire to be connected. As more people own these devices, there are greater opportunities for data acquisition in Intelligent Transportation Systems, and for vehicle-to-infrastructure communication. Horizontal curves are a common factor in the number of observed roadway crashes. Identifying locations and geometric characteristics of the horizontal curves plays a critical role in crash prediction and prevention, and timely curve warnings save lives. However, most states in the US face a challenge to maintain detailed and highquality roadway inventory databases for low volume rural roads due to the laborintensive and time-consuming nature of collecting and maintaining the data. This thesis proposes two smartphone applications C-Finder and C-Alert, to collect two-lane road horizontal curves data (including radius, superelevation, length, etc.), collect this data for transportation agencies (providing a low-cost alternative to mobile asset data collection vehicles), and for warning drivers of sharp horizontal curves, respectively. C-Finder is capable of accurately detecting horizontal curves by exploiting an unsupervised K-means machine learning technique. Butterworth low pass filtering was applied to reduce sensor noise. Extended Kalman filtering was adopted to improve GPS accuracy. Chord method-based radius computation, and superelevation estimation were introduced to achieve accurate and robust results despite of the low-frequency GPS and noisy sensor signals obtained from the smartphone. C-Alert applies BLE technology and a head-up display (HUD) to track driver speed and compare vehicle position with curve locations in a real-time fashion. Messages can be wirelessly communicated from the smartphone to a receiving unit through BLE technology, and then displayed by HUD on the vehicle’s front windshield. The field test demonstrated that C-Finder achieves high curve identification accuracy, reasonable accuracy for calculating curve radius and superelevation compared to the previous road survey studies, and C-Alert indicates relatively high accuracy for speeding warning when approaching sharp curves

A software tool approach to re-evaluating superelevation in relation to drainage requirements and vehicle dynamics – a case study

Paper presented at the 31st Annual Southern African Transport Conference 9-12 July 2012 "Getting Southern Africa to Work", CSIR International Convention Centre, Pretoria, South Africa.There is a growing public demand for safer streets and highways. Designing safer roads requires a need to review and improve the existing design guidelines. Road widening and general roadway rehabilitation projects are designed according to the existing roadway conditions. As a result, drainage problems associated with superelevation are prevalent. An evaluation of design alternatives in terms of safety, taking into consideration the superelevation values in relation to the drainage requirements and vehicle dynamics, will prolong the design process. However, it is believed that the additional time invested will result in safer roads and a reduction in vehicular accidents and in addition a potential in lower construction costs. This latter benefit is derived by limiting instances where a design component is overdesigned. The objectives of this paper is to (1) develop drainage criteria for flow paths and depths on road surfaces due to superelevation, (2) analyse the speed and vehicle dynamics at sharp or reduced horizontal curves, (3) develop superelevation criteria for steep longitudinal grades on sharp horizontal curves by identifying and analyzing associated drainage problems and (4) present the outcomes of an independent software tool to assist geometric designers and authorities in the civil engineering industry to design ‘safe’ roads from a geometric design viewpoint by taking factors such as time, cost, quality and context-sensitive design solutions into consideration. The paper draws from an innovative desktop literature analysis study and presents an overview of the research objectives. The desktop study is complemented by the analyses of data from user and stakeholder samples conducted on a section identified on National Route 3. Various physical and theoretical methods of analysis are described in the paper and the ultimate observations and findings will be published in a geometric design manual. The software tool simulates the stormwater drainage flow path in relation to the design superelevation criteria values assessed and evaluated to prevent hydroplaning. The resulting outputs will present a theoretical review of the geometric design considerations involved. The South African Minister of Transport reiterated that we need to prevent the number of accidents on our roads and this paper seeks to persuasively identify a solution from a geometric design perspective. We need to design safer roads.This paper was transferred from the original CD ROM created for this conference. The material was published using Adobe Acrobat 10.1.0 Technology. The original CD ROM was produced by Document Transformation Technologies Postal Address: PO Box 560 Irene 0062 South Africa. Tel.: +27 12 667 2074 Fax: +27 12 667 2766 E-mail: nigel@doctech URL: http://www.doctech.co.zadm201

Reconciling Speed Limits with Design Speeds

In recent years, context-sensitive highway design has been promoted to ensure that designers consider the environmental, scenic, aesthetic, historic, community, and preservation aspects of the road. Context-sensitive design may lead to situations where the current design standards cannot be met because of restricting local conditions. Indiana has road sections designed and built some time ago. In a considerable number of roads with the statutory limit of 55 mph (90 km/h), the road geometry does not meet the current standards. At individual intersections and on curves, advisory speeds are posted together with warning signs. Although this solution increases the safety of road users and allows for traveling at reasonably high speeds outside of these segments, the final solution is to upgrade their geometry to the desirable level. This report presents models that predict user-selected percentile free-flow speeds on two-lane rural and four-lane rural and suburban highways. The percentile speeds are computed as a linear combination of the mean speed and the standard deviation in panel data models with random effects. The developed percentile speed models involve more design variables than typical speed models, and separate the mean speed factors from the speed dispersion factors. These benefits ease the model interpretation and its use in highway design. The study results should help designers bring the predicted speed to the desired speed as close as possible given the budget constraints. Engineering judgment can then be applied to balance safety and construction cost in highway improvement projects

Critical Speed Analysis of Railcars and Wheelsets on Curved and Straight Track

The railway train running along a track is one of the most complex dynamic systems in engineering. Its operation has two main features: motion in a train of vehicles, and guidance by adhesion with the track. Kinematic analysis of railway vehicles and wheelsets facilitates the evaluation of the relative motion between the many vehicles in the train and the motion between the train and the track. This thesis explores the kinematics of the dynamic system of the train running along a track using basic physical principles. Engineers can use this understanding to calculate speed limits for established rail lines and calculate angles and distances that are of fundamental interest in the design of new train components and track. This work presents the derivation of the kinematic behavior of railcars and railway wheelsets on both curved and straight track and looks at how these motions change on inclines, or grades. It then explores how the kinematic equations are affected by industrial parameters such as locomotive speed, tonnage, track geometry, and railcar dimensions, resulting in a more complete picture of how individual variables factor into the overall kinematics of a running locomotive. The work ultimately discusses how this parametric analysis of kinematic derivations can shed light on current industrial problems of traffic flow optimization

Automatic High-Fidelity 3D Road Network Modeling

Many computer applications such as racing games and driving simulations frequently make use of 3D high-fidelity road network models for a variety of purposes. However, there are very few existing methods for automatic generation of 3D realistic road networks, especially for those in the real world. On the other hand, vast road network GIS data have been collected in the past and used by a wide range of applications, such as navigation and evaluation. A method that can automatically produce 3D high-fidelity road network models from 2D real road GIS data will significantly reduce both the labor and time needed to generate these models, and greatly benefit numerous applications involving road networks. Based on a set of selected civil engineering rules for road design, this dissertation research addresses this problem with a novel approach which transforms existing road GIS data that contain only 2D road centerline information into 3D road network models. The proposed method consists of several components, mainly including road GIS data preprocessing, 3D centerline modeling and 3D geometry modeling. During road data preprocessing, topology of the road network is extracted from raw road data as a graph composed of road nodes and road links; road link information is simplified and classified. In the 3D centerline modeling part, the missing height information of the road centerline is inferred based on 2D road GIS data, intersections are extracted from road nodes and the whole road network is represented as road intersections and road segments in parametric forms. Finally, the 3D road centerline models are converted into various 3D road geometry models consisting of triangles and textures in the 3D geometry modeling phase. With this approach, basic road elements such as road segments, road intersections and traffic interchanges are generated automatically to compose sophisticated road networks. Results show that this approach provides a rapid and efficient 3D road modeling method for applications that have stringent requirements on high-fidelity road models

Debris flow dynamics: A flume study of velocity and superelevation

Debris flows are powerful, geophysical flows with the potential to cause fatalities and damage infrastructure. The hazard posed by these events is often related to the velocity of the flow. However, due to their spontaneous nature and rapid onset, opportunities to observe debris flows are rare. The aim of this investigation was to improve the understanding of debris flow dynamics in curved channels using a hardware laboratory flume model. The purpose-built, variable slope, 8 m long flume enables a variety of debris flow boundary conditions to be studied. Here, 60 experimental tests were carried out at four slope of – 15°, 17°, 23° and 25°; for both straight (12 tests) and curved channels (48 tests). The modular construction of the flume enabled purpose-made channel curves to be inserted in the straight channel. Four channel bends with differing geometries were tested; three radii of curvature – 0.4, 0.55 and 0.7 m (for a bend angle of 40°) and one radius of curvature of 0.7 m for a 20° bend angle. For all runs the grain-size of the debris flow mixture consisted of a poorly sorted gravel/sand/clay mix (bulk density 1880 kg m-3, water content 17%). A combination of direct and video-based observations were used to record debris flow behaviour including variation in superelevation and the average and local velocity of the flow. Channel gradient is shown to be an important factor in controlling debris flow velocity. The straight channel results demonstrate a strong linear relationship between debris flow velocity and channel gradient. Modelling debris flow hydraulics reveals a power-law relationship, suggesting Newtonian turbulent flow conditions. The magnitude of superelevation was strongly linked to debris flow velocity, radius of curvature and bend angle. Superelevation was shown to increase in a power law relationship with debris flow velocity, which was greatest for tighter bend geometries. A decrease in radius of curvature resulted in a non-linear increase in superelevation, while decreasing the bend angle promoted a decrease in superelevation. When compared to observed superelevation, predicted values from the superelevation equation can substantially overestimate by up to 210% in some circumstances, suggesting that predicted values and back-calculated velocity estimates should be regarded as maxima. Furthermore, calculation of ‘k’ from experimental data suggests that ‘k’ was not constant (varying by two-fold) and has a value less than ‘1’, contrary to the proposed theory. This novel investigation has studied the influence of debris flow velocity, radius of curvature and bend angle upon superelevation, broadening the very limited knowledge base surrounding debris flow superelevation and its controls. For future studies it is recommended to: increase the number of experimental runs for each channel configuration; use a wider range of radii of curvature and bend angles; and improve the accuracy of the superelevation equation by introducing a parameter to account for bend angle, and to better define the significance and value of ‘k’

Evaluation of the Highway Safety Manual Crash Prediction Model for Rural Two-Lane Highway Segments in Kansas

While there have been numerous previous studies performed to develop the rural two-lane segment crash prediction models as part of the Highway Safety Manual (HSM), no previous study has been developed to validate the accuracy of the current model for states other than those the model was developed for. To address this gap the Kansas Department of Transportation (KDOT) commissioned this study to analyze both the accuracy and the practicality of using these crash prediction models on Kansas highways before deciding whether or not to implement the models as part of their normal project development process. To accomplish these goals this dissertation first determined gaps in KDOT data versus data requirements of the HSM. This effort identified an important inconsistency between the Kansas highway system and how the HSM recommends application of the model. Next, the model was calibrated using both the HSM procedure and new procedures that address specific qualities of the Kansas highway system. The calibration procedure derived through this dissertation outperformed the HSM procedure and shows promise as a model for calibration in other jurisdictions. Finally, the accuracy of the crash prediction models for Kansas highways was determined and a calibration procedure was recommended for implementation