On December 31, 2014, a terrible tragedy occurred in Shanghai, where around 300,000 people had gathered for the new-year celebrations on the Bund, a water front promenade which is part of Shanghai's historic downtown. Overcrowding on a staircase leading to an observation platform left thirty-six people dead and forty nine more injured.
This is only one sad example of the deadly force stored in crowded events. Human stampedes occur almost annually in music festivals, sports events religious festivals and night clubs. Famous examples are the July 2010, Love Parade music festival in Duisburg, Germany, where 21 people died from suffocation and at least 510 more were injured. In January 2006, over three hundred pilgrims died in Saudi Arabia as the result of overcrowding at the Jamarat Bridge, a pedestrian bridge that is part of the path believers walk through while performing the ritual Hajj pilgrimage to Mecca.
But what exactly is crowd control?
“We need to differentiate between crowd control that is done with access control tools, for example controlling a large number of spectators in a closed football stadium, and crowd control in an uncontrolled open environment like a street. The first one is achieved with conventional tools like security check points, turnstiles, gates and CCTV with video analytics based counters. The second one is usually closer to ‘safe city' projects and is more challenging and complicated since it is difficult to cover a wide area filled with people, be it for counting purposes or behavior analysis” explained Hagai Katz, Senior VP Business Development and Marketing at Magal Systems.
Accurate estimation of the number of attendees is indeed crucial for successful crowd control. Underestimating the number of people attending the Shanghai New Year's Eve was one of the factors leading to the tragic consequences. The police underestimated the number of attendees and assigned only about 700 officers (compared to 6000 officers in previous years) to handle a crowd that turned out to be 300,000 people.
In Germany, about 1 million revelers attended the Love parade venue that could only hold 250,000.
Role of video surveillance
In general, video surveillance cameras are still the main sensor for real-time crowd control and monitoring; “HD and IP network cameras have become the trend. 4K surveillance cameras have started to enter the market, but it is unlikely they will disrupt the surveillance segment. The cost of video transmission, storage, and processing (video analytics) would be prohibitive for 4K camera. Reliability would also be an issue” said Karianto Leman, Head, Situational Awareness Analytics Program, A*Star's Institute for Infocomm Research (I2R) in Singapore.
“For effective crowd control and monitoring, high-resolution video is critical to achieve situational awareness, as well as the ability to see greater detail within certain areas of interest. Today that means megapixel 180-degree cameras” stated Steve Gorski, Chief Sales Officer at Scallop Imaging. Scallop Imaging's cameras simultaneously combine output from multiple image sensors creating a continuous panoramic image that can cover a large outdoor scene. “We've seen a trend moving away from pan-tilt-zoom (PTZ) cameras because inevitably, when an incident occurs, it's likely that the PTZ camera is positioned somewhere else, and not able to see the action. Another reason for this trend is that the motor inside PTZ cameras tends to wear out over time” he added.
Portable solutions for Temporary Events
Unlike fixed venues, short term events like music festivals, sports competitions or city marathons pose a unique challenge for outdoor crowd control. The needed infrastructure is not always readily deployed and end-users face a dilemma of whether to make a big investment in infrastructure that will be used only for a few days.
A recent trending solution for such a scenario is the deployment of a temporary surveillance system using a wireless mesh network, which is easy to establish and then take down during an incident or public event. Because it doesn't require a fixed infrastructure, a mesh network is commonly deployed by public safety departments, municipalities and police forces. “The network is usually made up of mesh network software, digital cameras, workstations, a server and mesh nodes (hardware) that share information with one another wirelessly. Radios, smart devices or mobile devices of some kind often provide communication pathways between operators. Video analytics and other technologies can then be deployed in these temporary systems” detailed Ian Westmacott, Computer Engineering Manager, Tyco Security Products .
San-Diego based MicroPower Technologies offers a solar powered wireless system that allows deployment on a per-need basis.
“Flexibility is key. Utilizing an integrated solar/wireless surveillance system as an extension of the broader surveillance system allows users to deploy and redeploy the cameras as their needs evolve” explained Dave Tynan, Vice President of Global Marketing and Sales, MicroPower Technologies. “We're seeing growing interest in technology that can be quickly and easily installed directly at the points where it is needed most. Rather than, for example, installing fixed cameras on a building and then attempting to gain usable footage of a crowded event several blocks away, customers want to be able to place cameras closer to the hot spots of risk. This is particularly true for night activity, when placing cameras closer to the action helps take advantage of available light. The result is clearer, more usable video evidence” he added.
The benefit of this solution is the ability to deploy cameras according to immediate needs, e.g. at a parking lot during a major event, and then re-deploy them to other hot spots in the next big event without running costly and time consuming cables.
However, an important factor that needs to be taken into account is the limited transmission range that wireless cameras have and the image quality which is not Megapixel. This type of portable solution is suitable for securing a defined ‘hotspot' but might not be as relevant when securing the long route of a marathon.
Portable solutions are not just for video surveillance. temporary fences and even vehicle barriers are available. “Parking for temporary events like football games, political meetings, freshman matriculation day and open houses requires only a temporary solution. Our solution is in the form of portable, towable barriers. These barriers can be deployed quickly and effectively, even in places where it's impossible to excavate for a permanent foundation,” said Greg Hamm, Vice President, Sales & Marketing, Delta Scientific. “These mobile crash barriers can be towed into position by a medium-sized pick-up truck or equivalent. They deploy in 15 minutes and can be operated locally or remotely for guard protection. Deployment, retrieval and operation are all hydraulic. The barriers stop and disable a 15,000-pound vehicle (6803 kg) moving at 30 mph (48 kph). Once positioned, the mobile barricade is separated from its transporter and lowered into position by means of a battery-operated hydraulic power system, which is then used to raise or lower the barrier for normal or emergency tasks”, described Hamm.
Information transmission
Another challenge outdoor events pose is how to transmit high quality video streams from the cameras to a remote security center reliably and in a cost efficient way for processing, storage and viewing. There are several option including transmitting the information over cable, over a dedicated wireless networks, or using 3G/LTE networks. “In the latter configuration, cameras will compete in bandwidth with civilian cell phones that use the same network” explained Leman, “The solution is to reduce the requirement to transmit video all the time. This can be done with an edge computing device that runs video analytics. The device stores video locally and will only stream back video when a video analytics alarm is triggered” he added.
Wireless networking for surveillance solves the need for cables, which might not always be optional or easy to install (either due to specific area considerations or due to cost if it is a temporary event). However, this type of networking is more difficult than wired networking: having to overcome difficulties such as, limited range, obstructions (houses, trees etc.) and complicated configurations when many cameras are involved. NVT's IP transmission product technology allows for the deployment and PoE powering of cameras, event monitors and other IP sensor devices deployed at great distances using very cost effective coax cable.
“In the case of the recent NY City Marathon, NVT supplied coax connected transmission devices that needed to be fully operational at distances of up to 3,000ft in order to provide effective situational awareness for the securing of this large event” described Guy Apple Vice President, Marketing and Sales Network Video Technologies.
Physicists are trying to understand the dynamics of crowds. Their analysis of video footage from events like the Saudi Arabian pilgrims stampede and the German Love Parade helped identify the phenomenon termed “crowd turbulence” – as the scene becomes more and more crowded, more and more people push forward trying to move. The overall pressure of the masses moves through the crowd causing people to fall and eventually to be crushed to death. Hopefully, advances in video surveillance and video analytics will give better ways to count people and identify the ‘tipping-point' beyond which a crowded event has the potential to become deadly.
>>> Crowd control: video analytics and alternative surveillacne cameras