Traditionally, a blind person has relied on a guide dog or a long cane to navigate the environment.
With the introduction of new technologies such as real-time passenger information systems, there are an increasing number of ways to help blind travellers for which the additional cost is not prohibitive.
What is wayfinding?
Wayfinding encompasses all of the ways in which people orient themselves in physical space and navigate from place to place.
A typical journey for a traveller will involve more than one mode of transport. For example, it might involve walking to the bus stop, a bus to the railway station, walking from the bus to the train platform, a train to another town, walking from a train to the taxi rank and a taxi to final destination.
Working out the optimum combination may not be a simple task since it may be a function of price, times of public transport and accessibility aspects. At present there is no generally available information service which provides a comprehensive service for journey planning including accessibility aspects.
The environment in which we live is becoming increasingly complex; even a bus journey across a city requires a range of skills including:
- Being able to avoid obstacles on the pavement
- To walk in the right direction
- To safely cross the road
- To know when you have reached a destination (e.g. found the correct bus stop)
- To know which is the right bus
- To pay the correct fare
- To find a vacant seat
- To know when to alight from the bus
These tasks may seem trivial, but for someone with no useful vision they are skills which have to be learnt. Even for someone with low vision, all these tasks are less easy than for someone with normal sight.
Over the last thirty years, engineers have devoted considerable resources to developing electronic systems to help a blind person avoid obstacles; these use technology such as ultrasonics, lasers and infra-red.
Many of the devices just provided information about the range of the nearest object; a 'picture' could be built up by moving the sensor from side to side. Other devices have attempted to give a more complete image of the environment but at the expense of providing an excessive amount of information to the blind user.
The capacities of the senses of hearing and touch are very small compared to that of the visual channel for a human. Selecting and processing the information to make best use of the non-visual channels is not a simple task. The sensors in future devices are likely to involve more than one modality (e.g. both a video camera and an ultrasonic transceiver) in order to obtain the necessary data which can be processed to produce an accurate image of the immediate environment.
For a blind person, the problem of getting about is not just that of not walking into objects. One problem is that of knowing the layout of the environment; here, an embossed map can help. However, embossed maps are not easy to produce or interpret since just embossing a sighted map seldom leads to an intelligible embossed map.
Even with an embossed map and a mobility aid, it is still very easy for a blind person to get lost. A number of electronic orientation aids have been developed, but few have been widely used because of the cost of modifying the environment.
One type of system uses infra-red transmitters mounted at street corners; the infra-red signal is modulated so that a receiver, held by the blind person, gives out an audible message. These systems can also be used to indicate the status of traffic lights. Similar radio-based systems have been used in some countries, and the advent of Bluetooth is likely to dramatically reduce the cost of installing such systems.
A different concept is for the blind person to carry a tag similar to the ones used in shop security systems. Thus, machines can detect the presence of a blind person within a few metres and modify their behaviour (e.g. give out a speech message). The tag or smart card can be pre-coded, which could indicate that the person would prefer messages in an alternative language.
Satellite navigation systems can be used to determine one's position to a few metres. However, this requires line-of-sight to three or four satellites, which means being outdoors and not close to tall buildings. This position is just given as latitude and longitude, so it needs to be integrated with a detailed digital map of the area.
The availability of sufficiently detailed digital maps has proved to be a significant problem. Digital maps designed for car drivers do not give the detail needed by a blind pedestrian. Ideally the map should not just show the bus stop, but also provide information about which buses stop there.
Numerous wayfinding systems have been proposed, and many have been successfully developed to demonstrate the technical feasibility of the system. However, what is lacking is a clear plan for implementing systems and services so that blind users do not have to cope with different systems in each area.
If you would like further information and recommendations on Wayfinding Technologies please click on the following link: Wayfinding Technologies.
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