Dongli Gao

City University of Hong Kong | CityU · Department of Civil and Architectural Engineering

The faster-is-slower effect (FIS), which means that crowd at a high enough velocity could significantly increase the evacuation time to escape through an exit, is an interesting phenomenon in pedestrian dynamics. Such phenomenon had been studied widely and has been experimentally verified in different systems of discrete particles flowing through a...

Fire tests with both methanol and propane fires ranging from 5.6 to 16.8 kW were conducted in two 1:20 reduced-scale tunnels with identical cross-section size of 0.45 m wide × 0.23 m high but different lengths, i.e., 20.8 m and 10 m long respectively. Natural smoke control was adopted for both tunnels. Fires were located at the center of the tunnel...

A 1/20 reduced-scale model tunnel with the sizes of 20.8 m long, 0.45 m wide and 0.23 m high and varying slopes from 0 to 5% were adopted to investigate the impact of slopes on the self-extinction of fire in the tunnel under natural ventilation. The mass loss rates of methanol fires with nominal heat release rates of 2.8, 5.6, 11.2 and 16.8 kW were...

Preventing the fresh air from reaching the fire seat by sealing the portals or placing obstructions is a promising approach to put out a fire in long tunnels. A series of fire tests using methanol fuel with nominal heat release rates of 5.6 kW and 11.2 kW were carried out in a 1/20 reduced-scale model tunnel with the sizes of 20.8 m long, 0.45 m wi...

Exit choice is essential for pedestrian safety and evacuation efficiency during the context of an emergency. Cumulative prospect theory is a widespread realistic decision-making theory that can transform choice outcomes and probabilities into subjective terms and integrate them as a parameter of cumulative prospect value (CPV), which determines the...

Grouping is a common phenomenon that occurs everywhere. The leader-follower relationship inside groups has often been qualitatively characterized in previous models using simple heuristics. However, a general method is lacking to quantitatively explain leadership in an evacuating group. To understand the evolution of single-group dynamics throughou...

Evidence suggests that in the event of a fire accident, a certain number of building occupants escape through smoke-filled environments. Consequently, evaluating the corresponding evacuation performance under such life-threatening conditions is important for advancing fire safety analyses. This study aimed to develop a fire-integrated evacuation mo...

In evacuation models, individual interactions are typically assumed to follow the certain rules which are decided using prior knowledge. Our proposed improvement in evacuation modelling is inspired by the real-life experience that during crowd movements, individuals usually place their visual focus on the movements of their neighbours, even in the...

The faster-is-slower eect (FIS), which means that crowd at a high enough velocity could significantly increase the evacuation time to escape through an exit, is an interesting phenomenon in pedestrian dynamics. Such phenomenon had been studied widely and has been experimentally verified in dierent systems of discrete particles flowing through a c...

Understanding human decision making during emergency evacuations is important. It is because decision making is crucial at each stage of the evacuation (e.g. route choice, exit choice, path finding, etc.). Previous studies have examined the influence of social interaction and environmental factors on exit choice. However, researches on the decision...

An inefficient evacuation system can lead to high levels of fatalities arising from natural or anthropogenic disasters. As the movements of and interactions between evacuees can greatly affect the overall evacuation patterns and times, in-depth investigations of evacuees’ behaviours and interactions are warranted. The cellular automata (CA) model,...

The heat release rates (HRRs) in fire experiments with gaseous fuels in tunnels were generally determined by the product of supplying fuel rates and their heat of combustion with the assumption that gaseous fuels could combust completely irrespective of ventilation conditions. In this paper, systematic calibration of the HRRs of propane fires at va...

The critical velocity is the minimum velocity blowing towards the fire seat in tunnels to reduce the length of back-layering to zero, and it has been extensively adopted in the design of longitudinal smoke control in tunnels. A new concept, i.e., sub-critical velocity, is proposed in lieu of critical velocity for longitudinally ventilated tunnels....

Air curtain is an effective means to stop the propagation of smoke in buildings to provide smoke-free area for safe egress of occupants in case of fires. To understand its effectiveness of smoke confinement in tunnel fires, full-scale tests were conducted in a tunnel of 140 m long and with varying heights of 5.0 m to 5.9 m and varying widths of 5.8...

Within the last decade, a number of crowd accidents have attracted the interest of scientists to study the movement of crowd under high levels of competition. An interesting finding in crowd dynamics is that the presence of an obstacle at an appropriate distance in front of an exit can improve flow rate. A numerical simulation based on the discrete...