A new microscopic model for the simulation of shared space schemes

Shared space is an innovative streetscape design which seeks minimum separation between vehicle traffic and pedestrians. Urban design is moving towards space sharing as a means of increasing the community texture of street surroundings. Its unique features aim to balance priorities and allow cars and pedestrians to co-exist harmoniously without the need to dictate behaviour. There is, however, a need for a simulation tool to model future shared space schemes and to help judge if they might represent suitable alternatives to traditional street layouts. This thesis presents a microscopic mathematical model to simulate pedestrians and 4-wheeled motorised vehicles in shared space schemes. The complete development of the model is addressed: mathematical formulation of three interrelated layers based on the Social Force Model (SFM), software implementation, calibration and validation using the case studies from New Road (Brighton) and Exhibition Road (London). Microscopic pedestrian, vehicle and mixed traffic models are reviewed and evaluated with respect to their ability to reproduce behavioural phenomena, resulting in the SFM being adopted as the most suitable basis for this thesis. The behavioural patterns of shared space users are analysed to identify specific manoeuvres that need consideration. These patterns are realised in a three-layer model: The first layer introduces the flood fill algorithm to define intermediate destinations for agent’s path around obstacles to the final destination. The second layer explains how the SFM is modified for pedestrians and vehicles. The third layer describes conflict avoidance with minimal change of speed and direction. The new mathematical model is calibrated and validated according to defined performance indicators using real data from the two case study sites. The results show that this model is suitable to simulate shared space users but that the physical parameters depend on how a shared space scheme is realised compared to the original philosophy. The achievements of this thesis can be beneficial to urban planners and councils considering the implementation of a new shared space scheme.Open Acces

Calibration and validation of a shared space model: case study

Shared space is an innovative streetscape design that seeks minimum separation between vehicle traffic and pedestrians. Urban design is moving toward space sharing as a means of increasing the community texture of street surroundings. Its unique features aim to balance priorities and allow cars and pedestrians to coexist harmoniously without the need to dictate behavior. There is, however, a need for a simulation tool to model future shared space schemes and to help judge whether they might represent suitable alternatives to traditional street layouts. This paper builds on the authors’ previously published work in which a shared space microscopic mixed traffic model based on the social force model (SFM) was presented, calibrated, and evaluated with data from the shared space link typology of New Road in Brighton, United Kingdom. Here, the goal is to explore the transferability of the authors’ model to a similar shared space typology and investigate the effect of flow and ratio of traffic modes. Data recorded from the shared space scheme of Exhibition Road, London, were collected and analyzed. The flow and speed of cars and segregation between pedestrians and cars are greater on Exhibition Road than on New Road. The rule-based SFM for shared space modeling is calibrated and validated with the real data. On the basis of the results, it can be concluded that shared space schemes are context dependent and that factors such as the infrastructural design of the environment and the flow and speed of pedestrians and vehicles affect the willingness to share space

Minimum energy route optimisation of a quad-copter UAV with landing incentivisation

Recent advancements in the technology surrounding UAVs have expanded the possibility of incorporating them into current logistical solutions. In order to accurately assess their capabilities, it is important that minimum energy trajectories can be generated to increase the travel range of a UAV as well as its possible number of visited locations. However, in current formulations of the optimisation problem, UAV dynamics do not incorporate a contact force on the ground. This results in hover-to-hover trajectories where the duration of the journey is exactly equal to an arrival time which is set as one of the problem's parameters. Those solutions are likely to be energetically sub-optimal if an unnecessarily large value of arrival time is chosen. This paper introduces landing capability by modifying gravitational acceleration in the dynamics using a sigmoid function which approaches zero at the destination. In this way, the trip can be conducted in a shorter amount of time if it results in lower energy consumption. The new model is compared against an example from the literature, where the corresponding solution results in a reduction of the travel time and energy consumption by approximately 80%. It is also applied to a real-world example where it is demonstrated that a UAV can provide energy savings if it replaces a van completing a delivery in the Solent region of the UK

Long-range collision avoidance for shared space simulation based on social forces

Shared space is an innovative approach to improve environments where both pedestrians and vehicles are present, with integrated layouts to balance priority. The Social Force Model (SFM) was used to visualise pedestrian and car trajectories so that peaks of density and pressure at critical locations are avoided. This paper extends the SFM to consider a long-range collision detection and collision resolution strategy. The determination of potential conflicts is enhanced using principle component analysis for a set of agent's prior speeds and directions. This long-range collision avoidance strategy results in more realistic SFM-based trajectories for pedestrians and cars in shared spaces

Blind classification of e-scooter trips according to their relationship with public transport

E-scooter services have multiplied worldwide as a form of urban transport. Their use has grown so quickly that policymakers and researchers still need to understand their interrelation with other transport modes. At present, e-scooter services are primarily seen as a first-and-last-mile solution for public transport. However, we demonstrate that 50% of e-scooter trips are either substituting it or covering areas with little public transportation infrastructure. To this end, we have developed a novel data-driven methodology that autonomously classifies e-scooter trips according to their relation to public transit. Instead of predefined design criteria, the blind nature of our approach extracts the city’s intrinsic parameters from real data. We applied this methodology to Rome (Italy), and our findings reveal that e-scooters provide specific mobility solutions in areas with particular needs. Thus, we believe that the proposed methodology will contribute to the understanding of e-scooter services as part of shared urban mobility

Space Cooling Using Geothermal Single-Effect Water/Lithium Bromide Absorption Chiller

Abstract This research is proposed to fully investigate the performance of a single‐effect water/lithium bromide absorption chiller driven by geothermal energy. Since absorption cycles are considered as low‐grade energy cycles, this innovative idea of rejecting fluid from a single‐flash geothermal power plant with low‐grade energy would serve as efficient, economical, and promising technology. In order to examine the feasibility of this approach, a residential building which is located in Sharjah, UAE, considered to evaluate its cooling capacity of 39 kW which is calculated using MATLAB software. Based on the obtained cooling load, modeling of the required water/lithium bromide single‐effect absorption chiller machine is implemented and discussed. A detailed performance analysis of the proposed model under different conditions is performed using Engineering Equation Solver software (EES). Based on the obtained results, the major factors in the design of the proposed system are the size of the heat exchangers and the input heat source temperature. The results are presented graphically to find out the geofluid temperature and mass flow and solution heat exchanger effectiveness effects on the chiller thermal performance. Moreover, the effects of the size of all components of the absorption chiller on the cooling load to meet the space heating are presented. The thermal efficiency of the single‐flash geothermal power plant is about 13% when the power plant is at production well temperature 250℃, separator pressure 0.24 MPa, and condenser pressure 7.5 kPa. The results show that the coefficient of performance (COP) reaches about 0.87 at solution heat exchanger effectiveness of 0.9, when the geofluid temperature is 120℃