Requirements Engineering for Intelligent Traffic Light Control System for Emergency Vehicles - Case Study Example

In this thesis the problem of traffic in Riyadh with regards the to the movement of emergency vehicles is looked at. In this city high level of traffic pause a great challenge for emergency vehicles reaching their destination. In this, thesis two case studies have been looked at one looking at the physical infrastructure the used in implementation of emergency vehicle control system and the second involves simulation of traffic at an intersection to come up with an optimal traffic policy.  In this study simulation was used to represent flow at an intersection and to establish the optimal traffic policy in terms of green light control timing.

The results flowerheads simulation was similar to what would be expected in a real traffic situation. When all the Streets at the intersection were allocated green light time of 1 minute each the waiting time for Street 1 was found to be highest at 110.18s with the other streets having much lower waiting times. Increasing the green light time of Street maintaining minutes while maintain the green light time of the minute streets to 1 minutes reduced the waiting time of Street 1 to 53.19. This policy was found to be the best for Aboution.

With regard to emergency control simulation results indicated that Street 1 would require up to 5 minutes of green light time to allow an emergency vehicle to pass through the intersection. The transportation system in any country plays a vital role economically a security-wises to the country (Tyagi et al.,2009). The level of effectiveness of the transportation system is measured by its ability of supporting movement of people, goods and vehicles from various points in a reliable manner. Any urban traffic system is seen as a complex system that is composed of vehicles, pedestrians, traffic lights and the traffic network structure (Chabrol, 2006; Papa Georgiou, 2006).

Problems that are related to urban traffic have increasingly become a major concern and this has caught the attention of many researchers who are seeking for solutions (Chabrol, 2006). 

ith the huge number of vehicles have resulted to numerous problems including traffic jams, stress to drivers, air and noise pollution and increased fuel and energy consumption levels (Sheu, 2006). In principle continuous traffic flow form is modeled from a macroscopic view point, with a substantial influence from hydrodynamic theory. Here general variables such as rate of flow, density as well as average speed gives the description of traffic flow. Microscopic view on the other hand has its focus on individual vehicles behavior and thus modeling the discrete form in traffic flow (Wen, 2006).

Traffic signal control in urban areas in an important component with regards safety of pedestrians, vehicles drivers, passengers and the vehicles themselves when it comes to crossing an intersection or other paths (Liu, 2007). Traffic signals are used in controlling the time between different flows so as to avoid flow conflicts that are likely to arise. It is due to the concern of arising conflicts that resulted to invention of traffic signal in the early 1900s (Wen, 2008). Any urban traffic signal control system may be seen as being a complex system whose characteristics include randomness, burst and being uncertain (Dotoli, M. et al.,2006).

Putting to use a reliable model that is reliable that has the ability of reflecting the manner in which the traffic control system is behaving is vital in realizing real time control of the traffic signal. With a traffic control system in place, there is a considerable reduction in delay by vehicles tripping in a network of intersection (Boillot F. et al. ,2006). With a suitable control policy being put into use, a well designed urban traffic signal control can considerably reduce problems such as overcrowd, stop delays, high fuel consumption, air and noise pollution, discomfort and stress (de Oliveira, 2010).

The two groups of traffic control policy that may be put in place are the fixed time strategies and the vehicle motivated strategies. For the case of the fixed time strategies, usually they implemented off-line by use of a maximum efficiency codes on the basis important and historical traffic data. In this case there is no use of information of real time traffic conditions. For the case of vehicle motivated strategies, there is on-line synchronization and optimization of the signal scheduling programs.

This is a traffic reactive signal control policy making use of signal timing schedule with an automated answer to traffic requirement (Dotoli, M. et al.,2006). Because of the conflicting purposes, serious problems are usually encountered with regards control of signals at intersections. To come up with the best fluidity may sometimes create a best safety compromise while if emphasis is put on safety, it would imply having a constraint on traffic signal colour durations or correlations between traffic signals.

With these constraints in place, the implication is that there is a limitation on traffic fluidity management. On the other hand, the users of traffic networks such as pedestrian, emergency vehicle, and bicycle often have concern crossing of an intersection (Boillot F. et al. ,2006). 1.2 Wireless sensor network Wireless Sensor Networks (WSN) find application in many domains including weather monitoring, home automation, health care monitoring, military, security and safety etc. or it can be simply put that wireless sensor network find application in many areas.

Traffic Signal System or traffic monitoring is seen as a vast domain where application of WSN may be used in gathering of information concerning the incoming flow of traffic, traffic load a specific road, traffic load changes with time and vehicle prioritization. The installation of WSN along a road may be used in controlling the traffic load at intersection points. Sensor nodes installed along the road are usually small sized with low level energy consumption (Wenjie C. et al.,2006)) and the power may be provided by a battery or solar may be used.