What Design Elements Define At-Grade Intersections in Saudi Arabia?

In the Kingdom of Saudi Arabia, designing safe and efficient at-grade intersections is critical to modern road networks. By leveraging AI-based road asset management and integrating them into an advanced digital road monitoring system, planners can enhance performance, safety and longevity of intersections. In this blog we examine how AI in road design and safe intersection design practices are applied in Saudi Arabia, touching on geometry, traffic management, sight-distance, pedestrian facility provisions, channelisation and smart planning. We also connect this to broader themes of smart road design and planning, traffic management at intersections, and how agencies can adopt automated methods and asset-management workflows.

Regulatory and Design Framework in Saudi Arabia

Saudi standards such as the SHC 301 (Highway Geometric Design in Saudi Arabia) provide guidance for highway and intersection design in Saudi Arabia, emphasising flexibility, ergonomics and safety. The standard notes that many designs use ranges of values rather than fixed requirements, emphasising context sensitivity.

Key take-aways include:

• Intersections must be designed respecting the road hierarchy and target design speeds.
• Minimum vertical clearance for highways is specified (for example 5.50 m) for design consistency.
• Intersection geometry must provide adequate sight-distance for vehicles approaching minor legs.

These frameworks lay the groundwork for applying smart methodologies like automated inspection, digital monitoring and AI-driven asset management.

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Geometry and Layout of At-Grade Intersections

The geometric configuration of an at-grade intersection has major implications for safety and capacity.

Road Hierarchy and Intersection Type

Design manuals in Saudi contexts emphasise that the intersection type must align with the hierarchy of the intersecting roads. On major arterial roads, simpler forms of at-grade intersections or preferably signalised layouts are used. For example, in one regional manual, it is indicated that four-leg major/minor at-grade intersections may not be suitable for high-speed primary arterials.

Turning Radii and Channelisation

Turning curvature must accommodate the design vehicles anticipated at the intersection. While specific Saudi values may not always be published publicly, general guidance emphasises accommodating heavy vehicles in industrial areas, and providing splitter islands or channelisation where needed to reduce conflict points.

Sight Distance and Alignment

A fundamental requirement is that drivers approaching a major road from a minor leg must have unobstructed sight of the major road and the conflict point. The Saudi guidelines derived from SHC 301 emphasise view triangles, stopping sight distance and decision sight distances tailored to design speed.

Grade and Vertical Alignment

At-grade intersections must be located on or near level ground where possible. Some Saudi design sources stipulate that gradients approaching intersection stop/give-way lines should be very gentle (e.g., no more than 2% within a short length) to avoid sight and stability issues.

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Traffic Management and Operational Features

An efficient at-grade intersection is not just about geometry; the operational features play a major role in capacity, safety and usability.

1. Channelisation and Conflict Reduction

Using channelised left or right-turn lanes, splitter islands, dedicated signals and auxiliary lanes helps reduce vehicle conflict. Many Saudi design guidelines endorse physical or painted islands, and ensure that minor flows are separated from major carriageways to minimise risk.

2. Pedestrian and Non-Motorised Traffic Provisions

In urban Saudi contexts, pedestrian crossings at at-grade intersections must be clearly marked, with drop kerbs, tactile paving for accessibility, and clear sight lines. One regional manual states that if pedestrian volumes or speeds are high, grade-separated crossings should be considered instead.

3. Signalisation and Control Strategy

Where traffic volumes or conflicts exceed acceptable levels, signalisation or a roundabout may be preferred over a simple give-way layout. The decision must account for turning flows, traffic mix, pedestrian needs and future growth. Saudi design frameworks reference that at-grade intersections on high-speed arterials may need upgrading to grade-separation if conflict is high.

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Integration with Smart Technologies and Asset Management

Beyond traditional design, the modern paradigm in Saudi Arabia and globally is shifting toward smart road design and planning, leveraging data, sensors and AI to support AI-based road asset management and digital road monitoring systems. Here’s how intersection design can benefit:

1. Data-Driven Design and Monitoring

By collecting traffic flow data, vehicle classification, turning counts, pedestrian volumes and structural condition, agencies create detailed datasets. These permit scenario modelling and continuous monitoring of intersection performance.

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2. AI in Road Design and Performance Prediction

Artificial intelligence can analyse historical traffic and safety data, forecast turning flows, evaluate collision risk at intersection geometries and optimise layout or signal timing. This is especially relevant for AI in pavement strength assessment and analogous road-asset contexts. The use of sensors, cameras and IoT devices enables real-time detection of anomalies, congestion patterns or structural deterioration.

3. Lifecycle and Asset Management Approach

An intersection is a major asset in the road network. Applying automated pavement evaluation and smart monitoring allows for proactive maintenance, scheduling of upgrades (signal equipment, road markings, lighting) and budgeting via an asset management system. The result is better prioritisation, cost control and improved service levels.

4. Linking Design to Safety Audit

Smart intersection design must align with broader road safety audit processes. By interlinking safety audit findings with design geometry and AI-driven data, agencies can identify high-risk intersection types, remediate them and feed back into the design models for future improvement.

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Implementation Steps for At-Grade Intersection Projects in Saudi Arabia

For agencies or designers wishing to apply these principles in Saudi Arabia, a structured workflow is advisable:

1. Site Assessment and Data Collection
   Identify potential intersection sites, gather traffic volumes, turning counts, vehicle types, pedestrian flows, and existing geometrics. Conduct surveys using traffic-survey methods and inventory inspection.
2. Initial Geometric Layout
   Design intersection geometry in line with Saudi guidelines (e.g., SHC 301), ensuring proper sight distance, turning radii, appropriate lane widths, and accommodating design vehicles. Consider segregation of conflicting flows, channelisation and appropriate signalisation.
3. Operational Modelling
   Model traffic flow, queue lengths, delay, conflict points and pedestrian interactions. Use AI-based simulation tools to assess future demand, safety indices and performance.
4. Smart Systems Integration
   Install sensors, cameras and monitoring equipment. Connect the intersection into a digital monitoring system. Set up data feeds and AI analytics to track performance, identify incidents, monitor structural condition and forecast maintenance needs.
5. Asset Management and Safety Audit Loop
   Integrate intersection asset into your road-asset database under an AI-based asset management framework. Conduct safety audits to verify design and operational performance. Feedback learnings to update design standards and predictive models.
6. Continuous Monitoring and Optimisation
   Use the digital road monitoring system to track intersection health, traffic performance and safety metrics. Trigger maintenance, signal timing optimisation or redesign when thresholds are exceeded.

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Key Design Elements Recap

Here is a summary of the primary design elements that define safe and efficient at-grade intersections in Saudi Arabia:

• Appropriate road hierarchy classification and intersection type selection
• Adequate sight distances (stopping sight, decision sight) and alignment geometry
• Correct turning radii, channelisation, islands and conflict-point reduction
• Minimal gradients and good vertical/ horizontal alignment near intersections
• Pedestrian crossings, accessibility features and safe non-motorised traffic provisions
• Signalisation, capacity modelling and operational planning
• Integration with smart monitoring, sensors and AI for ongoing performance management
• Lifecycle asset management and connection to safety audit processes

By combining robust geometric design with smart road design and planning, and embedding the intersection into an overarching digital road monitoring system, authorities can elevate intersection safety, capacity and durability.

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Conclusion

Designing at-grade intersections in Saudi Arabia goes beyond simply connecting roads. With the advent of AI in road design, integrated asset management and digital monitoring platforms, intersections become dynamic nodes – optimised for safety, efficiency and lifecycle performance. A modern approach that couples the time-tested geometric guidelines from Saudi standards with automated pavement evaluation workflows and AI-based road asset management, will deliver next-generation intersections fit for the Kingdom’s fast-evolving transport infrastructure.

RoadVision AI is transforming road infrastructure development and maintenance with its innovative AI in road maintenance and AI in road construction solutions. By utilizing cutting-edge computer vision technology and digital twin models, the platform conducts comprehensive road safety audits, enabling the early detection of potholes, cracks, and other surface issues for timely repairs and enhanced road conditions. The use of AI in road safety also extends to traffic surveys, providing data-driven insights to tackle challenges like traffic congestion and optimize road usage. By adhering to IRC regulations and Saudi standards SHC 101 and SHC 202, RoadVision AI empowers infrastructure stakeholders to design safer roads, lower maintenance costs, and deliver efficient transport system

To explore how your organisation can implement these frameworks with smart data, intelligent monitoring and intersection optimisation, book a demo with us.

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FAQs

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Q1. What distinguishes an at-grade intersection design in Saudi Arabia from international practice?
Saudi guidelines emphasise flexibility, regional conditions (such as desert terrain) and design speeds aligned with local vehicle fleets. The use of Smart monitoring and asset management integration is increasingly emphasised.

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Q2. How does AI enhance intersection design and traffic management?
AI enables predictive modelling of turning flows, detection of safety risks, dynamic signal optimisation and integration of sensor data into an overarching asset management system.

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Q3. When should an at-grade intersection be upgraded to a grade-separated facility?
When traffic volumes, vehicle mix, speeds and conflict points exceed safe levels for a flat intersection, or when safety audits highlight recurring high-severity crashes, a grade-separated option becomes warranted.

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