Driving GIS innovation in route risk assessment

In October 2019, Sweco was appointed to provide transport and road safety consultancy through Transport Scotland’s Development Management and Road Safety Service Multi Supplier Framework.

The framework is being used to help implement the Strategic Road Safety Plan 2016 and deliver the ambitions of Scotland’s Road Safety Framework to 2030 which aims to reduce fatal and serious injury accidents to zero.

Sweco was appointed to Lot 2 of the framework and commissioned to develop a GIS-based Route Risk Scoring System for Scotland’s Trunk Road Network. The objectives of the commission are to identify and compare the level of risk on sections of routes across the network and to use this to help inform and prioritise targeted safety improvements.

Subsequently, since 2022, Transport Scotland and their Operating Companies have incorporated Sweco’s GIS-based Route Risk Scoring System into their annual assessment of road safety performance to identify risk and prioritise mitigations measures along Scotland’s trunk road network.

Transport Scotland will run a full update of the Route Risk Scoring System at appropriate intervals with data they hold and maintain internally on their road asset management systems to ensure the latest updates of the road network are embedded into the model and its outputs.”

The challenges

The Scottish Trunk Road network is split into Links and Sections on different lengths based on historical information, which makes comparisons challenging since it does not provide suitable break points that allow changes in carriageway types, speed limits and alignment.

For the purposes of the Route Risk Scoring System, 4,703km of the Trunk Road Network were broken down to new, equal length sections, based on a protocol to cover locations where a change in the features requires a section break.

Our solution

Datasets from Transport Scotland’s Asset Management System and other sources were collected, integrated, processed and analysed in a Geographic Information System (GIS) to calculate the required outputs.

To increase productivity, a number of bespoke GIS tools were developed in-house to automate the required geoprocessing and spatial analysis tasks for future data updates.

Sweco’s GIS and Road Safety teams developed and implemented the Route Risk Scoring Geographic Information System (RRS GIS), an innovative, GIS-based system which is:

• Integrating assets and features of the Scottish Trunk Road Network into a central ArcGIS File Geodatabase,
• Running a bespoke, multi-criteria analysis Route Risk Scoring Model (RRS Model), in the form of custom model tools and script tools developed with ArcGIS ModelBuilder and Python/ArcPy, to calculate the required Risk Score and Key Performance Indicators (KPIs) per section, and
• Mapping and visualising location-based analytics, such as hazard scores and risk scores, and KPIs through an interactive, cloud-based ArcGIS Dashboard on ArcGIS Online.

As part of the RRS Model, the Links and Sections of the Scottish Trunk Road Network were processed to create new, uniform, 500m-long sections to allow comparison of scoring. The Risk Score calculated per section is based on alignment, environmental, roadside and road condition hazards data, as well as traffic flow data.

In addition, nine Collision Rates are calculated per section to provide KPIs that assist in focusing attention on what matters most and decision making.

Outcome & benefits

Through this commission, Sweco continues and enhances their strong relationship with Transport Scotland. The Route Risk Scoring GIS has been well received by the client who have presented it to both internal and external stakeholders have recently rolled it out to their operating companies, with tangible benefits including:

• The central Geodatabase provides a single source of truth for the data used as part of the Route Risk Scoring System,
• The custom model tools and script tools for ArcGIS ensure accuracy in performing the required spatial analysis and geoprocessing tasks, while they create efficiencies by minimising the time required to run the processes,
• The ArcGIS Dashboard provides a dynamic, data-driven view of geographic information, designed to display multiple visualisations that work together on a single screen, offering a comprehensive view of the data and providing key insights for an at-a-glance decision-making,
• Transport Scotland can easily identify and compare the level of risk on sections of routes across the Trunk Road Network and use this to make informed decisions about where to target funding to remove risk on the trunk road network, and
• Sweco has successfully leveraged the ArcGIS technology that Transport Scotland has access to by creating an innovative, bespoke technical solution that improves their return on investment and adds value to their assets data inventory.

Sweco has enabled Transport Scotland to proactively identify risk along Scotland’s trunk road network and prioritise mitigations measures, by developing an innovative, GIS-based Route Risk Scoring System that shows our capability to work as a ‘team of teams’ to solve clients’ most challenging issues, develop comprehensive geospatial solutions and drive digital transformation to support informed decision-making.

Panagiotis (Panos) Chiotis Principal GIS Consultant