Abstract
It is essential for local authorities and public transport service providers to carry out public transport surveys regularly. These assist in the collection of data for use in public transport planning. The South African government, recognising the importance of acquiring and maintaining such information, came up with a policy that makes it compulsory for every local authority to have a current public transport record. To collect data for the current public transport record, one of the most commonly used surveys is a ride check survey. In order to get more accurate data form these surveys, some local authorities have adopted the use of global positioning systems (GPS), for accurate position location and hand-held digital computers for electronic data recording. Since most of the local authorities already have their data in GISs and use GIS, it becomes imperative to be able to store this survey data in the GIS. However, the huge amounts of data collected need to be stored efficiently, by minimizing data redundancy. This paper focuses on the development of a data model to efficiently include ride check survey data into a GIS. Implementation of the data model is based on the object-relational database technique and the dynamic segmentation method.

1. Introduction
It is essential for local authorities and public transport service providers to carry out surveys on public transport usage regularly. The data collected from these surveys is instrumental in the planning and design of public transport facilities and in planning for future use of public transport (Macpherson 1993).

The methods of data collection have evolved from manual methods to electronic methods and at the same time many local authorities are adopting the use GIS for transport information management and service planning. With continuing advances in technology, the extent, accuracy and amount of collected data is limitless. The only challenge lies in trying to organise this data so that it fits in with the rest of the local authorities?spatial and attribute data in the GIS and serves its intended purpose.

The objective of this paper is to investigate the representation of ride check survey data in a GIS. The next section provides an overview of how ride check surveys are conducted in Cape Town, South Africa. This will be followed by a discussion on how and why positioning systems and handheld digital computers have been adopted for use in these surveys. The rest of the paper then reports on the design and implementation of a suitable data model to include such data in a GIS.

2. Background
Recognising the importance of surveys to public transport service planning and information management, the government of South Africa has set up policies that make it compulsory for every local authority to maintain a current public transport record. This current public transport record should give an overview of the extent of public transport services and the availability and location of public transport facilities. It should also contain information on current public transport usage statistics and public transport users preferences and needs (Department of Transport 2001).
In order to acquire data on current public transport usage statistics and public transport users preferences and needs, each transport authority has to carry out public transport surveys. In Cape Town, South Africa, one of the most common surveys used to collect this data are ride check surveys (Moving Ahead 2001). Ride check surveys are also considered more advantageous than other public transport surveys, which involve the distribution of questionnaires to passengers, because ride check surveys are based on the observation method of data collection. This method leads to the collection of more accurate data because it does not rely on the respondent抯 willingness and ability to respond to the questions (Wermuth et al 2001).

Traditionally, during ride check surveys in Cape Town, a surveyor would board a public transport vehicle for the duration of one trip. The surveyor would manually record, at every stop, the number of people boarding or getting off the vehicle, the method of payment of the ticket for the passengers boarding the vehicle, descriptive information on the position of the stop and the stop number. This would present a problem when the vehicle stops at any place that is neither an existing stop nor a terminus. There would be no location information on that stop available in the database. Any attempts to represent such a place on a map results in an inaccurate representation because an approximate position will be used. Sometimes, when visibility is poor, the surveyor would find it difficult to read off the stop number from the stop shelter in the short time that the vehicle stops to drop off or pick up passengers. The manual recording of the arrival and departure times at each stop and the counting of the people getting on and off the vehicle would also result in inaccurate data due to human error and fatigue.

To overcome these shortfalls, some local authorities in South Africa have adopted the use of automatic positioning systems for location positioning and electronic data devices for recording the data during these surveys. It is also important to note that similar problems are being experienced in other countries and that the adoption of these devices is not only occurring in South Africa but can be seen as a worldwide phenomenon (Shaw 1999 and Murakami et al 1997). An example of the use of this technology in South Africa is the use of global positioning systems (GPS) and palm pilots by the Cape Metropolitan Council in carrying out ride check surveys in the year 2000 (AfriGIS 2000).

During these ride check surveys, a surveyor was placed on a selected bus trip, armed with a GPS receiver and a palm pilot. At every stop, the surveyor recorded the following information:

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