Tables and figures say an intersection will operate at a certain level of service, but traffic simulation shows you what that will actually look like: queues, weaving conflicts and choked entrances. It is a decision tool before the concrete is poured: is one entrance enough? Do you need a signal or a roundabout? Will the drive-through queue spill onto the street? For large projects, the procedural guide requires it explicitly. This guide explains what the guide requires, the difference between macro analysis and micro-simulation, when simulation helps smaller projects, and how to read levels of service.
What the Procedural Guide Requires
For large investment projects expected to generate more than 2,500 trips in the peak hour, the guide provides for:
- Starting with VISUM to analyse the overall flow of trips and understand the project's impact on the network.
- Then using VISSIM to simulate specific locations such as intersections, entrances, exits and parking.
- Identifying the need for operational improvements: signals, roundabouts, multiple entrances and road capacity.
- Intersections being clearly visible in the modelling.
- A report explaining the model methodology with an electronic copy of it.
- A transport model for the opening year and 20 years after project completion.
Macro Analysis vs Micro-Simulation
| Item | VISUM | VISSIM |
|---|---|---|
| Level | The whole network | Specific locations |
| Question it answers | Where do trips go and what is their effect on the network? | How do vehicles actually move at the intersection or entrance? |
| Outputs | Volumes and trip distribution on roads | Queues, delay, level of service and a visual presentation |
| Use | Understanding the overall impact and identifying critical points | Testing solutions and designing improvements |
When Does Simulation Help Smaller Projects?
- Drive-through and fuel station entrances on congested corridors. Read: Drive-through and fuel station design.
- Complex intersections near the project.
- Comparing improvement alternatives before choosing one.
- Convincing the relevant authorities of the proposed solution at the results meeting.
Level of Service
The guide defines level of service from A (the best operating condition) to F (congestion and severe delay), and requires improvements for intersections at level D or lower. Simulation helps prove that the proposed solution actually raises the level. Read: Why traffic studies are rejected.
What Does Good Simulation Need?
- Accurate count data taken at the right time. Read: Traffic count timing.
- Geometric measurements of roads and intersections and signal timings.
- Generated trips calculated with the approved methodology. Read: Data collection methods.
- Calibrating the model to current conditions before testing the future.
Read: When does the municipality require a traffic study?.
Frequently Asked Questions
Does every study need simulation?
The guide requires it for large projects, and it may help others depending on the site's complexity.
What is the difference between VISUM and VISSIM?
VISUM is for macro analysis at network level, and VISSIM for detailed simulation of specific locations.
How many years does the simulation cover?
For large projects, a model for the opening year and 20 years after project completion, according to the guide.
Does simulation help parking design?
Yes; entrances and parking can be simulated to test queues and operational capacity. Read: Parking dimensions.
Is the simulation submitted to the municipality?
The guide requires a report on the model methodology with an electronic copy of it.
How Abak Engineering Consultancy Helps
Abak is an accredited engineering office that carries out traffic simulation of intersections, entrances and parking, tests improvement alternatives before construction, and prepares models and reports in line with the procedural guide. See our intersection traffic simulation service, or contact us.
Regulatory information is based on the Balady platform and the Ministry of Municipalities and Housing, and procedures may be updated by the competent authority. Last reviewed: October 2026.