Case Study: Central Hatching in Perak, Malaysia
The iRAP Malaysia pilot project, completed in 2008, recommended that central hatching be used at selected locations on federal roads.
In 2010, the Malaysian Institute of Road Safety (MIROS) undertook a study to test the effectiveness of central hatching in Perak, Malaysia. The project involved the installation of central hatching on a 2.8km length section of four lane highway.
The study found that the central hatching resulted in a statistically significant reduction in speeds and better lane keeping.
Previous Research
- Sagberg (2007) tested two types of central hatching. He found the treatments increased separation between opposing traffic streams compared to conventional centerlines, and one type led to a reduction of traffic speeds by 2.7km/h.
- Researchers at the Monash University Accident Research Centre tested a range of centerline and edge line treatments. They found that the best combination for reducing travel speeds whilst increasing road safety was found to be a 2.5 m wide lane width road with a 2.3 m wide hatched median.
- The Land Transport Safety Authority (LTSA) in New Zealand found that installing ‘flush median’ reduced overtaking crashes by 28.9%. Overall, there was a 19% decrease in crashes at those sites.
New Road Layout
The layout of the new design is –
- Lane width – 3.4m – 3.6m
- Central hatching width – 1.0m
- Paved shoulder width – 1.5m
Evaluation Method
Video cameras were set up to record traffic at two locations along the road. Recordings were made before the central hatching was installed and afterwards. The cameras were 1.3km apart.
The resultant video recordings were used to determine the average speed for each vehicle as it travelled between the two camera locations (calculated by dividing the distance between the cameras by the time taken to travel between them) and the lateral position of each vehicle relative to the centre line or central hatching (by taking measurements from the computer monitor screen.
Results
The analysis found that after the central hatching was installed, there was a statistically significant reduction in average speeds of 3km/h and the percentage of vehicles exceeding the speed limit decreased by 5%. Separate research shows that even a small reduction in average speeds can translate into significant reductions in the risk that serious injury crashes will occur.
The lateral position measurements made before the central hatching was installed showed errant vehicles crossing the centerline and lane lines. The measurements made after the central hatching was installed showed an improvement in the lateral position of vehicles at both video camera sites, indicating better lane-keeping discipline.
Based on these findings, central hatching was considered to have the potential to reduce vehicle speed and to increase separation between opposing vehicles on a road, and hence potentially lead to a reduction in crashes.
The findings support road authorities’ use of central hatching as a cost-effective means of reducing road crash risk.
This case study was provided by the Malaysian Institute of Road Safety (MIROS).
References: Poi Wai Hoong, A. and Mohd Marjan, J. (2010) The Safety Effects of Central Hatching on Four-Lane Rural RoadiIn Malaysia. Malaysian Institute of Road Safety Research, Kajang, Selangor.
