Malaysia's Shah Alam Expressway Has Persistent Accident Black Spots — and the Type of Vehicle Involved Determines How Deadly a Crash Will Be
Researchers in Malaysia conducted spatial-temporal analysis of one of Malaysia's busiest inter-urban corridors – The Shah Alam Expressway. The research was led by corresponding author. S. Sarifah Radiah Shariff | shari990@uitm.edu.my | School of Mathematical Studies, Faculty of Computer and Mathematical Sciences, Universiti Teknologi MARA, Shah Alam, Malaysia.
Spatiotemporal analysis is widely used in road and transportation studies because traffic conditions, accidents, congestion, and infrastructure performance vary across both space (location) and time . Unlike traditional analyses that examine either geographic patterns or temporal trends separately, spatiotemporal analysis integrates both dimensions, enabling researchers to identify where and when specific events occur, detect emerging hotspots, and understand dynamic traffic behaviors. This approach provides a more comprehensive understanding of road safety and mobility patterns,
Crashes on the Same Stretches of Road, Year After Year
The study, published in The Open Transportation Journal, has mapped five years of road accident data on the Shah Alam Expressway — one of Malaysia's busiest inter-urban corridors — and found that crashes are far from randomly distributed. Between 2013 and 2017, a total of 2,823 accidents were recorded along the 34.5-kilometre route connecting Pandamaran to Sri Petaling. While accident numbers dropped by roughly 30% between 2013 and 2014–2015 following a peak of 728 cases in 2013, they climbed again to over 500 per year through 2016 and 2017, showing that early reductions were not sustained. More concerning, statistical analysis confirmed that accidents cluster tightly at specific locations rather than spreading evenly along the road, with a clustering result (z-score of 3.086, p = 0.002) that is statistically significant at smaller spatial scales. Three particular stretches — at KM40.5–40.9 in both travel directions, KM27.0–27.4 and KM47.5–47.9 eastbound, and KM49.0–49.4 westbound — repeatedly emerged as high-accident zones across all five years, with some segments recording up to 32 crashes in a single year. These locations correspond closely to toll plaza areas and interchanges, pointing to traffic complexity at these points as a likely contributing factor.
Most Crashes Are Minor — But What Determines Whether Someone Dies Is the Vehicle They Are In
The study also examined what makes some crashes far more deadly than others. Looking at the full dataset, 61.9% of accidents resulted only in property damage and 28.9% caused minor injuries, but 9.2% were serious or fatal — a proportion that is too high to ignore on a road designed for safe, high-speed travel. To understand what drives that severity gap, the research team applied an ordinal logistic regression model across each study year, testing four potential factors: vehicle type, weather, crash cause, and time of day. One factor stood out clearly and consistently — the type of vehicle involved. In 2013, motorcyclists faced odds of serious injury more than 20 times higher than occupants of other vehicle types. In 2014 and 2015, heavy lorries with three or more axles were the strongest predictor of severe outcomes, reflecting the enormous destructive force of a collision involving a fully loaded truck. By 2017, virtually every vehicle category — cars, motorcycles, and lorries alike — was significantly associated with higher injury severity. Weather conditions, the attributed cause of the crash, and whether it happened during the day or night did not consistently or significantly affect how bad an accident turned out to be, suggesting that once a crash happens on this expressway, it is primarily the vehicle type — and its associated mass, speed, and vulnerability — that determines the human cost.
Targeted Engineering and Vehicle-Focused Policies Are Needed — Not One-Size-Fits-All Solutions
The findings make a clear practical case: generic safety campaigns spread thinly across the full length of the expressway are less likely to work than focused interventions at the specific black-spot locations the data have identified. The authors recommend site-specific engineering improvements at persistently high-risk segments, particularly around toll plazas and interchange areas, including better road geometry, clearer signage, and smarter traffic flow management. They also call for vehicle-specific safety policies — dedicated and better-designed motorcycle lanes, tighter regulation of heavy vehicle speeds and loads, and targeted enforcement for the vehicle categories that consistently show up in serious crashes.
Read the published article here: https://bit.ly/4xOvUnq
JOURNAL
The Open Transportation Journal
DOI: 10.2174/0126671212488767260506035720
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The Open Transportation Journal
Spatial-temporal Patterns and Determinants of Accident Severity on the Malaysian Inter-urban Expressway: An Ordinal Logistic Regression Approach