Road agencies are increasingly involved in collecting a wide range of road use data including WIM data. These data types can come from a number of sources. There is also an increasing need to efficiently access the data within a jurisdiction, or from external parties including the public.
Data integration can be broadly defined as the bringing together of different types of road use data and other road data such as the inventory of road conditions in a central database. The integration can utilise several databases, with the capability of referencing the data using a unique referencing system such as road numbers and Geographical Information System (GIS) coordinates (Austroads 2004).
The range of road use and related data generally suitable for integration, and reflecting the diversity of traffic information needs, includes the following:
- traffic volumes, traffic composition (i.e. classified counts) and turning movement counts
- pavement loading data from WIM systems and weighbridges
- pavement condition rating
- transport demand data such as origin-destination
- route performance data, e.g. travel time, level of service or congestion index
- traffic management data from ITS, signal systems or freeway management systems
- road crash data, e.g. exposure measures, risk or black spots
- asset management data such as bridges, tunnels, signs and markings and guardrails.
The above list is not exhaustive and other data types can be included in an integrated database now and in the future. By combining data, it is possible to generate further information than in its separate parts, e.g. the Austroads National Performance Indicators Program. However, integration should not be interpreted as a simple combination of data such as averaging data sets, merging data from different time periods of a day or aggregating data across lanes. Also, raw data should be maintained in a database as far as possible.
Austroads recommends as a good practice that traffic data from counting stations, manual counts, WIM sites and signal systems be integrated as a first step. Other data to follow should include data previously mentioned – Austroads National Performance Indicators, road management data, crash rates and others.
- maintaining traffic section definitions on a road network
- managing the editing, storage and access to data on each traffic section, and at each count site
- maintaining count site locations
- maintaining relationships between count sites
- maintaining and publishing high level annual traffic statistics for count sites and road sections.
Some road agencies have further reported the use of proprietary WIM databases (e.g. WIMnet) to facilitate the processing, storage and access of WIM data. These databases perform additional functions such as calibrating for weight drift and time clock inaccuracies. They can assist with identifying overloading trends and associated axle configuration patterns.