⚡ electrical engineering

Impact of Non-Standard Road Bumps on Vehicle Suspension Dynamics, Ride Comfort, and Fatigue Life: A Comparative Study in Jordan

This study utilizes MATLAB and ANSYS simulations to demonstrate that the irregular road bumps common in Jordan cause significantly higher vibration, stress, and fatigue damage compared to standard profiles, thereby reducing ride comfort and suspension durability while advocating for standardized, smooth bump designs to improve vehicle performance and longevity.

Original authors: Belal ALemour, Omar Badran, Ayman Alawein, Omar Al-Mashaqbeh, Saif Ahmad, Yaseen Al-Wahsh

Published 2026-06-30

📖 5 min read🧠 Deep dive

CC BY 4.0

Original authors: Belal ALemour, Omar Badran, Ayman Alawein, Omar Al-Mashaqbeh, Saif Ahmad, Yaseen Al-Wahsh

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

Imagine your car's suspension system as a team of shock absorbers and springs acting like a trampoline for your ride. Its job is to keep the wheels glued to the road while making sure the people inside don't bounce around like popcorn.

This research paper, conducted by a team of engineers in Jordan, asks a simple but critical question: What happens to this "trampoline" when the road isn't built the way it's supposed to be?

Here is a breakdown of their findings using everyday analogies:

1. The Problem: The "Bad" Speed Bump

In many places, including Jordan, speed bumps are often built like jagged rocks or steep stairs (sharp, trapezoidal, or irregular shapes) rather than smooth hills. The researchers call these "non-standard" bumps.

The Analogy: Imagine walking up a smooth, gentle ramp versus stepping up a single, sharp concrete block. Both get you to the same height, but the block hurts your feet and shakes your whole body. That is the difference between a standard speed bump and the irregular ones found on many Jordanian roads.

2. The Experiment: A Virtual Crash Test

The team didn't just drive over bumps; they built a digital "quarter-car" model (a simulation of one wheel and the car body) in a computer program called MATLAB. They also used a powerful engineering tool (ANSYS) to look at the metal parts of the suspension as if they were under a microscope.

What they tested: They drove this virtual car over four types of bumps:
1. Sinusoidal: A perfect, smooth half-circle (the "ideal" bump).
2. Trapezoidal: A flat-topped hill with steep sides.
3. Sharp: A sudden, jagged spike.
4. Irregular: The messy, uneven bumps actually found on Jordanian streets.

3. The Findings: A Rough Ride

The results were clear: The shape of the bump matters more than just its height.

The "Jolt" Effect: When the car hit the sharp or irregular bumps, the suspension didn't just compress; it was violently shaken. The metal parts had to work much harder, creating high stress points.
The "Popcorn" Effect: Passengers in the car experienced much higher vibration levels. The researchers used a standard scale (ISO 2631) to measure comfort. Even with the smoothest bump, the ride was rated "Uncomfortable" to "Very Uncomfortable" at certain speeds. With the bad Jordanian bumps, the ride would be even worse.
The "Metal Fatigue" Effect: This is the most damaging part. Just like bending a paperclip back and forth until it snaps, the suspension parts were being stressed repeatedly.
- Smooth bumps: The suspension could last for millions of cycles (like a paperclip bent gently).
- Irregular Jordanian bumps: The suspension life dropped drastically, potentially failing after only a fraction of that time. It's like the difference between a car lasting 10 years versus breaking down in 2 years because the road is beating it up.

4. The Speed Trap

The study found that speed changes how the car reacts, but not always in the way you might think.

Going Slow: Surprisingly, going slower (30 km/h) over a bump sometimes caused more vertical movement because the wheels stayed in contact with the bump longer, allowing the suspension to compress fully.
Going Fast: Going faster (60 km/h) reduced the vertical bounce but increased the "jerk" or acceleration, making the ride feel rougher and more violent.
The Sweet Spot: There is a specific speed where the car hits a "resonance" (like pushing a child on a swing at the exact right moment), which makes the shaking much worse.

5. The New Tool: The "JRPSI" Score

The researchers realized that just measuring the height of a bump isn't enough to know if it's dangerous. A 10cm bump can be smooth or deadly depending on its shape.

The Solution: They created a new score called the Jordanian Road Profile Severity Index (JRPSI).
How it works: Think of it like a "Spiciness Scale" for roads.
- 0–25 (Safe): Like a mild soup. No problem.
- 25–50 (Moderate): A little spicy. Manageable.
- 50–75 (Severe): Very hot. Your suspension is sweating.
- >75 (Critical): Lava hot. Your suspension is in danger of breaking.
The Result: The smooth, standard bumps scored low (32). The messy, irregular Jordanian bumps scored dangerously high (86), landing in the "Critical" zone.

6. The Conclusion

The paper concludes that if cities want to save money on car repairs and keep passengers comfortable, they need to stop building jagged, steep speed bumps.

The Fix: Roads should use smooth, rounded (sinusoidal) shapes.
The Benefit: This reduces the "whiplash" on the car's metal bones, extends the life of the suspension, and stops passengers from feeling like they are in a washing machine.

In short: A speed bump shouldn't just be a wall to slow you down; it should be a smooth hill. If you build it like a wall, you break the car's legs.

Technical Summary: Impact of Non-Standard Road Bumps on Vehicle Suspension Dynamics, Ride Comfort, and Fatigue Life

Problem Statement
Traffic-calming devices, specifically speed bumps, are essential for urban safety but often induce adverse dynamic effects on vehicles. While international standards recommend specific geometries (e.g., sinusoidal, parabolic) to minimize vibration and structural stress, many developing nations, including Jordan, utilize non-standard, irregular bump designs. These irregularities—characterized by excessive heights, abrupt transitions, and inconsistent dimensions—generate severe dynamic loads. Existing research has largely treated ride comfort, vibration response, and structural durability as independent topics, often focusing on idealized road profiles. Consequently, there is a lack of integrated engineering tools to assess the holistic impact of the specific, irregular road bumps commonly found in Jordan on vehicle suspension systems, passenger comfort, and component fatigue life.

Methodology
The study employed an integrated numerical and analytical framework consisting of five sequential stages:

Field Characterization: A survey of Jordanian roads classified road bumps into four categories: sinusoidal, trapezoidal, sharp, and irregular non-standard profiles.
Dynamic Modeling: A two-degree-of-freedom (2-DOF) quarter-car model was developed in MATLAB to simulate suspension displacement, body acceleration, and vibration response. The model utilized a linear spring-damper configuration with tire stiffness, subjected to various bump profiles at speeds of 30, 40, 50, and 60 km/h.
Structural Analysis: A three-dimensional MacPherson strut suspension assembly was modeled in SOLIDWORKS and analyzed using ANSYS Workbench for transient structural behavior. This included stress distribution analysis and fatigue-life prediction using a stress-life (S–N) approach and Miner's Linear Damage Rule.
Ride Comfort Evaluation: Passenger comfort was assessed according to ISO 2631-1:1997 standards, utilizing frequency-weighted root-mean-square (RMS) acceleration.
Comparative Analysis: The study compared the performance of six representative passenger vehicles (ranging from economy to luxury classes) and developed a new assessment metric.

Key Contributions

Integrated Assessment Framework: The study uniquely combines dynamic simulation, transient structural analysis, fatigue prediction, and ride comfort evaluation within a single study to address the gap in integrated research regarding non-standard road bumps.
Jordanian Road Profile Severity Index (JRPSI): A novel engineering parameter was proposed to quantify road-bump severity. Unlike traditional geometric assessments, JRPSI integrates four dimensionless parameters: bump height, RMS vertical acceleration, maximum suspension deflection, and maximum equivalent stress. This provides a unified indicator for evaluating the combined impact of geometry, comfort, kinematics, and structural durability.
Field-Specific Data: The research provides specific data on the geometric characteristics of Jordanian road bumps and their comparative performance against international standards (e.g., Qatar, UK, New Zealand).

Key Results

Impact of Geometry: Irregular and sharp bump profiles generated significantly higher vibration levels, structural stresses, and fatigue damage compared to standardized sinusoidal profiles. The irregular Jordanian bumps resulted in a maximum equivalent stress of approximately 220 MPa, reducing the estimated fatigue life to between $1 \times 10^5$ and $5 \times 10^5$ cycles. In contrast, sinusoidal bumps yielded a stress of 90 MPa and a fatigue life exceeding $1 \times 10^7$ cycles.
Ride Comfort: Under the tested conditions, even standardized sinusoidal bumps produced "Uncomfortable" to "Very Uncomfortable" RMS acceleration levels (ranging from 1.27 to 2.31 m/s²) depending on vehicle speed. Irregular bumps are projected to exacerbate these levels further.
Vehicle Speed and Resonance: Vehicle speed significantly influenced dynamic response. Lower speeds (e.g., 30 km/h) resulted in greater suspension deflection due to longer wheel-bump interaction times, while higher speeds increased dynamic excitation. Resonance risks were identified when excitation frequencies approached the suspension natural frequency (approx. 1.23 Hz), particularly around 20 km/h.
Suspension Tuning: Vehicles with higher damping ratios (e.g., Mercedes-Benz, BMW) demonstrated superior vibration isolation and faster oscillation decay compared to vehicles with softer suspensions, though stiffer suspensions may increase high-frequency acceleration transmission.
JRPSI Classification: The calculated JRPSI values placed irregular Jordanian bumps in the "Critical" severity category (JRPSI = 86), whereas sinusoidal bumps fell into the "Moderate" category (JRPSI = 32).

Significance and Claims
The paper claims that its findings highlight the critical need for standardized road-bump designs, specifically advocating for smooth sinusoidal or gently ramped profiles to balance road safety with vehicle durability and ride quality. The study posits that the proposed JRPSI serves as a practical engineering tool for transportation authorities to evaluate existing traffic-calming devices, prioritize rehabilitation, and support future infrastructure standardization. By demonstrating that non-standard bumps can reduce suspension fatigue life by an order of magnitude, the research underscores the long-term economic and safety implications of poor road-bump design. The authors conclude that adopting the proposed methodology and JRPSI framework can help mitigate the negative impact of non-standard road infrastructure on vehicle suspension systems and passenger comfort.