Burnett (2000) defined IVNS as systems which are used to guide drivers when driving within unfamiliar places and direct drivers to the destination using most possible optimal route. Thielmann (2006) added that the driver puts in the destination using postal address or by clicking on the map then the system responses to this entry. Thielmann pointed out that the system will then present the optimal route either visually or/and aurally from the current position to the destination using functions and other technologies such as GPS technology and shortest path algorithms.
Mark et al. (1987) cited that Donald Cooke (1985) introduced the term vehicle navigation appliance which stands for the hardware and software that are used in vehicles in order to display the vehicle position on the ground and guide the vehicle to a destination. They claimed that the first navigation system in vehicles was commercially produced by Honda in 1981 which was called’’ Gyrocator’, this system was based on using a gyroscopic compass and overlaid transparent maps but it was not a success.
They continue to say that another system was tested in 1983 by Toyota called NavCom which is based on using a ruler and a map so as the driver reaches the destination the distance indicator approaches zero, although this system was better than Gyrocator, but it was not accurate with a mile distance error. Mark et al. mentioned that a more accurate and more successful navigator was called Etak navigator which was produced in California, US in 1985 which was owned by General Motors Corporation.
They indicated that Etek is more efficient than the previous navigators within an accuracy of 50 feet per hundreds miles and with a highly functional electronic map display. A significant progress in vehicle navigation system followed the civil use of NAVSTAR GPS, while previously all the IVNS did not use GPS in navigation but only relied on using dead reckoning (DR) technology (Quddus, 2006). DR is used to estimate the current position of vehicle according to a previously determined position which is already been entered by the driver in the system.
According to him the next position is estimated according to known speed of the vehicle and known time. The major shortage of DR is that it maximises the navigation error with the distance travelled because it measures the vehicle location relative to a reference point (Quddus 2006). The integration between GPS and DR is now used to overcome the errors that might occur in each of them in order to maximise vehicle routeing accuracy (Kao, 1991).
The GPS signals are used to calibrate the DR while DR is used to overcome position errors and when there is loss of GPS signal when is used around natural and man made obstructions such as trees, mountains, tunnels… etc. (Fang, 2004 and Kao, 1991). Kalman Filter (KF) is used in this integration process which is a digital algorithm that provides a way of computing and combining errors and use them to correct noisy sensor inputs to achieve optimal overall system performance, these inputs are from GPS receivers, gyroscopes, odometers, nearly vertically oriented accelerator and altimeter (Quddus , 2006 and Legat et al.
2000) Mainly there are two uses of this term in Emergency Medical Services (EMS). Scott et al. (1978) and Esri white paper (2007) defined the response time as the total amount of time from a dispatch point of the ambulance cars /fire trucks to the arrival at the incident location. While, DH UK (2007) defines the response time for the ambulance services for NHS as the total amount of time from receive of emergency call in the control centre to the arrival of the medical service to the incident location as shown in table 1.
Despite the different use of response time term, all the studies agreed that the most important issue in EMS is to reduce response time to the incident location in order to safe lives or to mitigate the consequences of any emergency incident and every second lost will reduce the possibility of patient survival and recovery (W. A. S. NHS, 2006).
For the purpose of this research response time is defined as the total amount of time between the dispatch of ambulance vehicle and the arrival of the vehicle at the incident scene. EMS can be defined as a service that provides “rapid assessment, timely provision of appropriate interventions, and prompt transportation to the nearest appropriate health facility by the best possible means to enhance survival, control morbidity, and prevent disability’’, (Kobusingye et al. 2006, pp. 126).
This service integrates personnel (such as ambulance driver) and equipments (such as ambulance vehicles and GPS) in order to provide the help possible to those in need of urgent medical care (VDH, 2003). The use of IVNS results a great importance to quicken the emergency response in ambulance vehicles and fire fighting trucks routings (Cross et al. , 2002). They mentioned that integrating this system along with GIS and other technologies offers higher accuracy and performance in emergency management applications.
The IVNS was used in a huge project which was provided by Falck Denmark to Track Danish Ambulance Fleet by installation a GPS in every ambulance vehicle to transmit the positions of each vehicle collected by GPS using wireless radio and this radio is used to connect these GPS to GIS software in the control centre in order to track the fleet (Baumann, 2002). This project was important for emergency service in Denmark to improve the respond time by guiding the closest ambulance vehicle to any emergency incident location.
A study by (Derekenaris et al. 2000) appreciates the importance of using an intelligent navigation systems technology in building an effective ambulance management system in Attica, Greece. This system uses GIS in routing the ambulance from the hospital to the incident site and from that site to the closest hospital calculating the quickest path which based on implementing the cost weights that is associated with each segment in roads networks. The cost in this system is a function of the length of roads and traffic volume.
The optimum route is then displayed on a small PC screen in the vehicle transmitted from the operation centre. In this system, the location of the emergency caller is acquired by matching the caller home phone number to the addresses in the database, while getting the cellular number of the caller is collected with the help of the cellular provider. The GPS is used to choose the closest emergency ambulance vehicle to the incident because every vehicle is mounted with a GPS to track their positions by the centre.