Signal Timing Calculator
Signal Timing Results
What Is a Transportation Signal Timing Calculator?
A transportation signal timing calculator is an engineering tool designed to estimate required signal time per phase at an intersection. The goal is to balance traffic movement, reduce delays, and maintain safety while giving enough time for vehicles and pedestrians to clear the intersection.
This online tool follows standard engineering assumptions, including values based on HCM 2010 methodology, which is commonly used around the world for preliminary signal planning.
Why Signal Timing Matters
Traffic signals are more than red-yellow-green lights. Proper timing plays a major role in:
✔ improving intersection safety
✔ reducing waiting time
✔ preventing traffic congestion
✔ improving pedestrian movement
✔ increasing capacity of junctions
✔ reducing fuel consumption
✔ smoother driving experience
When timing is planned correctly, the road network feels faster and safer for everyone.
Key Inputs Explained (Beginner-Friendly)
Your calculator uses five practical inputs shown in the panel:
1. Peak-Hour Traffic Volume
This represents the number of vehicles per hour during busy times.
Higher volume means more green time is usually needed.
Example:
1200 vehicles/hour = moderate traffic
4000+ vehicles/hour = heavier flow
2. Number of Approach Lanes
The number of lanes affects the saturation flow and capacity.
Example lane capacities:
- 1 lane ≈ 1800 vehicles/hour
- 2 lanes ≈ 3600 vehicles/hour
- 3 lanes ≈ 5400 vehicles/hour
- 4 lanes ≈ 7200 vehicles/hour
More lanes = more flow = shorter delays
3. Pedestrian Volume
Pedestrian activity affects the pedestrian clearance time.
The calculator automatically assigns additional seconds when pedestrian volume is above 100 peds/hour.
4. Desired Cycle Length
Cycle length is the total time for one complete signal sequence.
Some common cycle lengths:
- 60 seconds for light traffic
- 90 seconds for medium cities
- 120+ for large intersections
5. Intersection Type
Different intersection layouts need different timing factors:
| Type | Complexity | More Phases | More Clearance |
|---|---|---|---|
| T-Intersection | Low | No | Short |
| Four-way | Medium | Yes | Moderate |
| Complex 4-way | High | Yes | Longer |
| Rotary / Multi-phase | Very high | Many | Longest |
How the Calculator Works (Simple Explanation)
The model calculates:
- Effective Green Time
- Yellow Change Interval
- All-Red Clearance
- Effective Capacity
- Volume-to-Capacity Ratio (V/C ratio)
It also considers:
- pedestrian delay
- saturation flow
- lane capacity
- safety clearance time
Outputs You Will See
Your tool automatically displays the following results:
✔ Green Time (per phase)
Recommended seconds of vehicle movement.
✔ Yellow Change Time
Safety transition between green and red.
✔ Red Clearance Time
Time to clear vehicles still in the intersection.
✔ Effective Capacity (veh/hr)
Theoretical maximum number of vehicles the intersection can serve.
✔ V/C Ratio
Shows congestion levels:
- less than 0.85 = ideal
- 0.85 to 0.95 = moderate congestion
- above 0.95 = oversaturated
Why This Calculator Is Useful (Real-world benefits)
Faster Flow
Signal optimization improves movement during peak traffic.
Better Pedestrian Safety
Appropriate crossing time reduces pedestrian risk.
Reduced Delay
Better timing reduces waiting time at red lights.
Lower emissions
Less idling = better environmental performance.
Perfect for quick planning
This calculator is ideal for students, engineers, and planners.
Who Should Use This Calculator?
This tool is designed for:
- Transportation engineers
- Urban planners
- Civil engineering students
- Traffic researchers
- ITS planners
- Smart city designers
Even non-engineers can understand the results due to the simple interface.
Example Use Case
Imagine a busy four-lane city intersection with heavy pedestrian movement. You enter:
- 3500 vehicles/hour
- 2 lanes
- pedestrian volume: 300/hour
- cycle: 90 sec
- intersection: complex
The tool estimates signal timing that helps planners compare whether cycle length needs adjustment or lanes should be reconfigured.
How the V/C Ratio Helps Decision-Making
Volume-to-capacity ratio (V/C) tells you whether an intersection is over-loaded.
| V/C Ratio | Traffic Condition |
|---|---|
| 0.70 | Easy traffic |
| 0.85 | Near capacity |
| 0.90–1.00 | Heavy delay |
| >1.0 | Oversaturated |
This helps decide if:
- lanes should increase
- cycle length must change
- pedestrian timing needs revision
Disclaimer
These results are estimates based on typical traffic engineering rules. Real projects should always include field studies, professional planning, and HCM-based analysis.
