Application Software: Prior to 1984, the data was maintained in a purpose-built system held at the Department for Transport (DFT) in Hastings. In 1984, the data was transferred to a SIR (Statistics and Analysis, Integrated Applications, Relational Database) management system manufactured by SIR Pty Ltd of Milsons Point, New South Wales, Australia. From 2004 the data was analysed using Microsoft Access 2000.
Logical structure and schema: With the transfer to a SIR database, in 1984, the data was copied from old computer files and up until 1982, only two records were available: information (VEHICLE), and journey information (JOURNEY). From 1982, the data was held in 4 records: vehicle information (VEHICLE), journey information (JOURNEY), journeys comprising 1 to 4 stops (MULTISTP), and journeys comprising more than 4 stops (MULTITRP). The JOURNEY records were not input from the survey questionnaire but were derived from the MULTISTP and MULTITRP records.
In 2003, major changes in the Continuing Survey of Road Goods Transport (CSRGT) sample methodology took place following a quality review of the DFTs road freight surveys. In accordance with these changes, the DfT decided to procure a replacement database system to support the CSRGT (GB) Survey Process. Note that this new CSRGT (GB) system was originally held in SQL-Server format but the Department sought to analyse all of its data by means of a MS Access database. As complete details for the CSRGT (GB) system structure are unavailable, it is only presumed that the SQL-Server and the Access database were intrinsically linked in relationship to one another. Only the MS Access component of the system has been selected for permanent preservation.
How data was originally captured and validated: The data is based on a sample of about 350 vehicles each week. The operator of the vehicle provides details of all trips undertaken in one week; including domestic and foreign trips. Data includes type of activity, weight of vehicle, public and own account operation, length of haul, commodities carried, appearance of load and inter-regional flows. From 1989 fuel consumption was included. The data was collated using a questionnaire a copy of which can be viewed within the Reports of the Continuing Survey of Road Goods Transport 1977-2005, as held in the documentation.
Constraints on the reliability of the data: There is some inconsistency in the format of vehicle registration mark data (REGKEY): some marks have preceding spaces, and others have one or more embedded spaces separating the mark components. For this reason, searches based on the REGKEY field may give incorrect results if exact matches are specified.
Validation performed after transfer: Details of the content and transformation validation checks performed by NDAD staff on the Survey of Heavy Goods Dataset are contained in the dataset catalogues.