Recent research at the University of Central Florida addressing crashes on Interstate-4 in Orlando, Florida has led to the creation of new statistical models capable of calculating the crash risk on the freeway (Abdel-Aty et al., 2004; 2005, Pande and Abdel-Aty, 2006). These models yield the rear-end and lane-change crash risk along the freeway in real-time by using static information at various locations along the freeway as well as real-time traffic data that is obtained from the roadway. Because these models use the real-time traffic data, they are capable of calculating the respective crash risk values as the traffic flow changes along the freeway. The purpose of this study is to examine the potential of two Intelligent Transportation System strategies for reducing the crash risk along the freeway by changing the traffic flow parameters. The two ITS measures that are examined in this research are route diversion and ramp metering. Route diversion serves to change the traffic flow by keeping some vehicles from entering the freeway at one location and diverting them to another location where they may be more efficiently inserted into the freeway traffic stream. Ramp metering alters the traffic flow by delaying vehicles at the freeway on-ramps and only allowing a certain number of vehicles to enter at a time. The two strategies were tested by simulating a 36.25 mile section of the Interstate-4 network in the PARAMICS micro-simulation software. Various implementations of route diversion and ramp metering were then tested to determine not only the effects of each strategy but also how to best apply them to an urban freeway. Route diversion was found to decrease the overall rear-end and lane-change crash risk along the network at free-flow conditions to low levels of congestion. On average, the two crash risk measures were found to be reduced between the location where vehicles were diverted and the location where they were reinserted back into the network. However, a crash migration phenomenon was observed at higher levels of congestion as the crash risk would be greatly increased at the location where vehicles were reinserted back onto the network. Ramp metering in the downtown area was found to be beneficial during heavy congestion. Both coordinated and uncoordinated metering algorithms showed the potential to significantly decrease the crash risk at a network wide level. When the network is loaded with 100 percent of the vehicles the uncoordinated strategy performed the best at reducing the rear-end and lane-change crash risk values. The coordinated strategy was found to perform the best from a safety and operational perspective at moderate levels of congestion. Ramp metering also showed the potential for crash migration so care must be taken when implementing this strategy to ensure that drivers at certain locations are not put at unnecessary risk. When ramp metering is applied to the entire freeway network both the rear-end and lane-change crash risk is decreased further. ALINEA is found to be the best network-wide strategy at the 100 percent loading case while a combination of Zone and ALINEA provides the best safety results at the 90 percent loading case. It should also be noted that both route diversion and ramp metering were found to increase the overall network travel time. However, the best route diversion and ramp metering strategies were selected to ensure that the operational capabilities of the network were not sacrificed in order to increase the safety along the freeway. This was done by setting the maximum allowable travel time increase at 5% for any of the ITS strategies considered.

Yes / To terminate gait, the mechanical work-done by the lower-limbs is likely to be predominantly negative but how such work is produced/completed has not previously been investigated. The aim of this study was to determine the amount of negative mechanical (external) work-done by the lower-limbs, along with the associated joints (muscle) work, to terminate gait and how these work contributions were affected by a change in surface angle. Eight males completed terminations on the level floor and a declined ramp. Negative mechanical limb-work (limbW(−ve)) was computed (each orthogonal direction) as the dot-product of the ground-reaction-force and centre-of-mass (CoM) velocity. Inverse dynamics was used to calculate ankle, knee and hip negative joints (muscle) work (Wj(−ve)). Measures were determined for each limb for the two-locomotor steps of gait termination. The trailing-limb did 67% (−0.386 J/kg) of the overall limbW(−ve) to terminate gait on the level; and this increased to 74% (−0.451 J/kg) for ramp trials. Wj(−ve) was greater for the trailing- (ankle −0.315; knee −0.357; hip −0.054 J/kg) compared to terminating- limb (ankle, −0.063; knee −0.051; hip −0.014 J/kg), with the increases in ankle Wj(−ve) being temporally associated with increases in perpendicular limbW(−ve). Wj(−ve) increased on both limbs for declined compared to level surface, particularly at the knee (declined −0.357, level −0.096 J/kg), with such increases being temporally associated with increases in parallel limbW(−ve). These findings provide new perspectives on how the limbs do work on the CoM to terminate gait, and may be helpful in designing prosthetic limbs to facilitate walking on ramps. / ZA was funded by the Higher Committee of Education Development in IRAQ (HCED).

The purpose of this research was to develop an algorithm that could predict ramp meter wait time at metered freeway on-ramps throughout the state of Utah using existing loop detector systems on the ramps. The loop detectors provided data in 60-second increments that include volume, occupancy, and the metering rate. Using these data sources, several ramp meter queue length algorithms were applied; these predicted queue lengths were then converted into wait times by using the metering rate provided by the detector data. A conservation model and several variations of a Kalman filter model generated predicted queue lengths and wait times that were compared to the observed queue lengths. The Vigos model—the model that yielded the best results—provided wait time estimates that were generally within approximately 45 seconds of the observed wait time. This model is simple to implement and can be automated for the Utah Department of Transportation (UDOT) to provide wait time estimates at any metered on-ramp throughout the state.

Ramp descent is a demanding task for trans-tibial amputees, due to the difficulty in controlling body weight progression over the prosthetic foot. A deeper understanding of the impact of foot function on ramp descent biomechanics is required to make recommendations for rehabilitation programs and prosthetic developments for lower-limb amputees. The thesis aim was to determine the biomechanical adaptations made by active unilateral trans-tibial amputees (TT) using a microprocessor-controlled ankle-foot prosthesis in active (MC-AF) compared to non-active mode (nonMC-AF) or elastically articulated ankle-foot device. A secondary aim was to determine the biomechanical adaptation made by able-bodied individuals when ankle motion was restricted using a custom made ankle-foot-orthosis and provide further insight into the importance of ankle dynamics when walking on ramps. Kinetic and kinematic data were recorded from nine TT’s and twenty able-bodied individuals. Able-bodied participants, ankle restriction, led to an increase in involved limb loading response knee flexion that is accompanied by the increased knee power generation during the single-limb-support phase that correlates to TTs results. TT’s use of an MC-AF reduced the ‘plantar-flexion’ resistance following foot contact allowing foot-flat to be attained more quickly. Followed by the increased ‘dorsi-flexion’ resistance which reduced the shank/pylon rotation velocity over the support foot, leading to an increase in negative work done by the prosthesis. These findings highlight the importance of having controlled ankle motion in ramp descent. Use of an MC-AF can provide TTs controlled motion for descending ramps and hence provide biomechanical benefits over using more conventional types of ankle-foot devices. / Engineering and Physical Science Research Council (EPSRC) via Doctoral Training Account (DTA) (EP/P504821/1) Chas. A. Blatchford and Sons Ltd., Basingstoke, UK provided the prosthetic hardware, prosthetist support, and facilitated the attendance of the TT participants for this study

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Highway safety has been a priority for many years now. A system-wide crash analysis is a practical solution when only a limited budget is available for improving safety of highways. A systematic approach, in contrast to a hotspot analysis, allows for a widespread installation of lower-cost countermeasures across the highway network. This study focuses on the safety evaluation of a particular facility type, urban freeway off-ramps, in terms of its geometric and traffic characteristics. 144 off-ramp segments in Richmond, VA were evaluated based on the crash data available from 2011 to 2015. A statistical model was developed that relates crashes to the geometric and traffic characteristics of each off-ramp segment. A test for independence was performed to identify if a statistically significant difference existed between type of collision and severity of crashes with respect to ramp geometry and traffic control. Significant geometric and traffic variables were then identified from the model and independence test to assist in the selection of low-cost countermeasures. AADTs of both freeways and off-ramps were found to be the most statistically significant variables. Installation of advance warning signs for better traffic management near the freeway diverge area and clearing roadsides of fixed objects to reduce rear-end collisions are low-cost solutions for crashes on urban off-ramps in the study area. The results of this study demonstrate an approach to safety evaluations that could support transportation planners and agencies in identifying system-wide locations to install or apply appropriate low-cost countermeasures. / Master of Science

Middle Mississippian ramp carbonates in Kentucky (Fort Payne to Salem interval) form a large scale depositional supersequence (0 to 500 feet thick, approximately 8 m. y. duration). It formed on and in front of the abandoned Early Mississippian Borden deltaic marine paleoshelf, which had up to 100 m of relief above the adjacent starved basin. Major facies consist of marine quartz sandstone and shale; peritidal carbonates; high-energy ramp margin, crinoidal-bryozoan grainstones; deeper ramp mounds, skeletal grainstone/packstone sheets and channel-fills interlayered with shale or calcisiltite; and slope deposits of siliceous calcisiltite. Regional slopes on the paleoshelf edge and ramp margin are 0.5 to 2.5 mIkm (less than 0.25 degrees), although clinoforms of 2 to 10 degrees occur locally associated with mounds and depositional lobes. The supersequence LST is dominated by mounds interlayered with green shaly, deeper ramp facies. The mounded units are located in a fairway that is normal to the Borden margin but parallel to the Appalachian Grainger deltaic shelf. No TST is evident, except for a glauconite horizon capping the Borden paleoshelf. The supersequence HST consists of at least eight third-order sequences (each approximately 1 m.y. duration), the older ones downlapping onto the shelf 20 to 30 m deep, the younger ones downlapping into the deeper basin (over 150 m water depth). Sequences show marked toplap with the upper sequence boundary. The third-order sequences locally have lowstand sands, some of which may be associated with a paleodrainage system off the Borden paleo shelf. They lack recognizable TSTs, but have well-developed prograding HST units of nearshore shale and peritidal dolomite, skeletal packstone/grainstone banks, and siliceous calcisiltite slope facies. The supersequence correlates with a global sea level cycle in the lower Visean terminating in a major sea-level fall. The highly clinofonned toplapping supersequence reflects this long term, sea-level fall which prevented space from being created on the old delta top. The third-order sequences, although mappable between the sections, are not easily correlated with global third order cycles. / Master of Science

Firstly, this dissertation proposes a new characterization and classification method for daily sky conditions by using the daily sky clearness index (KD) and the daily probability of persistence (POP-KD) that can be derived from ground-based irradiance measurement data. Quality of daily solar irradiance is characterized by a newly proposed parameter, POP-KD. This characterized daily quality is varying and uncertain at the middle level of the quantity, but high and more certain at very high and low quantity levels. In addition, the proposed characterization method shows interesting results for KD and POP-KD: a statistical consistency for multiple years and similarity for their seasonal trends. The classification results also indicate an existence of dominant classes, and transitions between the dominant classes are significant for all locations. This dissertation also generates annual synthetic sequences of KD and POP-KD using a Markov approach. The generated sequences show statistical similarities with observed sequences. Secondly, this dissertation proposes methodologies to estimate day-ahead solar irradiance using the National Weather Service (NWS) sky cover forecast. For model development, this paper splits up a direct estimation process from the sky cover forecast to solar irradiance into two stages: forecast verification and cloud-to-irradiance conversion. Uncertainty for each stage and for the overall estimation process is quantified. NWS forecast uncertainty (about 20%) is identified as the main source of uncertainty for the overall process. In addition, verification of the sky cover forecast shows approximately 20% overestimated bias at days with a high irradiance level. Thus, the NWS sky cover forecast needs to be adjusted based on the type of day. This dissertation also proposes a conversion equation relating daily quantity of cloud information and daily quantity of solar irradiance. The proposed conversion equation achieves accuracy with simplicity. Five day-ahead solar irradiance quantity estimation methods are proposed in this dissertation. The proposed methods incorporate different schemes for dealing with the bias discovered in the cloud forecast. The observed data are regularly found within the 95% confidence intervals of the estimated values. Estimation results demonstrate the effectiveness of the conditional adjustment schemes at different irradiance levels. Lastly, this dissertation proposes a methodology to estimate day-ahead solar irradiance using fluctuation information of the NWS sky cover forecast. POP-KD was used as a parameter for the quality of daily solar irradiance. POP-KD efficiently represents the quality of daily solar irradiance. In addition, POP-KD indicates the probability that solar irradiance variability is within the ramp rates of common generators in power systems at a certain photovoltaic penetration level. This dissertation also proposes a new equation for the conversion from cloud fluctuation information to daily quality of surface solar irradiance. The proposed equation achieves accuracy. The proposed day-ahead solar irradiance quality estimation method is based on fluctuation information provided by the NWS sky cover forecast. This method uses a normalization approach to relate fluctuation of cloud forecast and fluctuation of cloud observation. The observed data are regularly found within the 95% CIs of the estimated values. / Ph. D.