Roundabouts are difficult to get in and out, traffic accidents are frequent, Sai Kung has the most accidents last year

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Written by: Chen Jiahui

2021-04-02 11:00

Last update date: 2021-04-02 11:00

When it comes to roundabouts, the driver feels all kinds of feelings in his heart, and his mind flashes through a certain thrilling or "dry bottom" experience.

For passengers, traffic jams at roundabouts are also commonplace.

Why is there a roundabout in Hong Kong?

Why is it prone to accidents and frequent traffic jams?

What can be improved?

"Hong Kong 01" interviewed traffic engineers and road research enthusiasts, trying to interpret the roundabouts in the city in terms of traffic planning, urban development, and local road user education.

(Part of series three)

The roundabout is probably the most difficult section of the road, because the driver is "multi-tasking", that is, turning, preparing for tangent, and paying attention to avoiding vehicles.

In fact, Hong Kong had 260 traffic accidents at roundabouts last year, with an average of more than 20 per month. There were also many serious traffic accidents at roundabouts, causing casualties.

Kwong Zixian, a traffic engineer and chairman of the Road Safety Research Group, pointed out that improving the safety of intersections is one of the advantages of roundabouts. However, if some roundabouts are too complicated, have many traffic lanes, or are connected at downhill sections of expressway exits, the risk of car accidents will be greater. increase.

260 roundabout traffic accidents in a year averaged 21 cases per month

According to statistics from the Transport Department and Highways Department, there are currently more than 330 roundabouts in Hong Kong. Shatin, Kwai Tsing and Outlying Islands have the most roundabouts, 39, 35 and 31 respectively.

A total of 15,298 traffic accidents were recorded in Hong Kong last year, of which 260 occurred at roundabouts (approximately 1.7% of all traffic accidents), an average of 21 cases per month.

Comparing different districts, the roundabout in Sai Kung District had the most traffic accidents, with 79 cases recorded last year, followed by Kwun Tong and Wong Tai Sin with 44 and 30 cases respectively.

There have also been serious traffic accidents in the past roundabouts, including the overturning accident of the tourist bus at the South Pin Wai roundabout in Sai Kung in 2008, resulting in 19 deaths and 43 injuries; in 2009, a double-decker bus accidentally overturned at the roundabout off Sheung Tak Estate, causing two deaths 33 hurt.

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Two roundabouts listed traffic black spots: Tsuen Tsing Interchange, Tsuen Kam Interchange

In response to enquiries, the Transport Department stated that there are currently two roundabouts in Hong Kong classified as traffic accident black spots, namely Tsuen Tsing Interchange (Tsuen Wan Road) and Tsuen Kam Interchange (Texaco Road North/Wai Tsuen Road).

In the second quarter of 2020, there were 49 traffic black spots in Hong Kong.

Tsuen Tsing Interchange (Google)

Regarding the former, Kwong Zixian explained that this place is a layered intersection of Route 5, connecting 5 groups of roads, with a lot of traffic, and a three-lane roundabout, which is very busy; if vehicles enter the roundabout from Tsuen Wan Road, they need to get off. Oblique, the speed is faster, and the driver brakes too late to cause accidents; the shape of the roundabout is not a perfect circle, and some vehicles may accelerate when entering a slightly slow section of the curve; and the line of sight along the central island of the roundabout is blocked by plants and bridge piers. It also increases risks.

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Tsuen Kam Interchange (Google)

As for the Tsuen Kam Interchange, Kwong pointed out that it is part of the layered interchange of Route 9 Highway. There are 6 groups of connecting roads. At the same time, there is a lot of traffic and three lanes, which is very busy.

He said that the two roundabouts have inherently undesirable places.

However, he emphasized that when assessing the relationship between the design and safety of a roundabout, it is necessary to count the main locations and patterns of car accidents to see whether they are random or have certain distributions or characteristics before a conclusion can be drawn.

The roundabout could have improved the safety of the intersection

However, Kwong also pointed out that one of the advantages of the roundabout itself is that it can significantly improve the safety of the intersection.

He explained that the rule of the roundabout is that the vehicles in the roundabout have priority, and at the same time the speed of all traffic is reduced, and the accidents are mainly oblique side collisions, and the severity of the accident is generally low.

In comparison, he explained that there is a priority at the intersection that the speed of the vehicle is faster. Once a collision occurs, a 90-degree collision is the main one. If it hits a weaker part such as a car door, it will easily cause serious injury to the passengers.

Kwong Zixian believes that the diversion design has many flaws and obvious mistakes.

(Information Picture/Photo by Zhong Weide)

Kwong continued that the roundabout also has two important safety functions, which not only can distinguish different road types, promote the adaptation of drivers, but also provide a safe way to turn around.

However, he also pointed out that if the roundabout is too complicated, the traffic lanes are too many and busy, or if it is connected at the downhill section of the expressway exit, the risk of a car accident will be greater.

Traffic lights, turbine-shaped roundabouts, etc. are worth studying

As for how to set up a roundabout to ensure safety?

Kwong pointed out that the secret of safety is to effectively control the speed of vehicles entering the maneuvering zone with a fine geometric layout. Appropriate signs are also required to guide drivers through safely.

He continued that the line of sight design for the roundabout is also a key point of the safety design and needs to be provided properly. Excessive or insufficient sight lines can cause problems.

He also suggested that the roundabout should be designed in a perfect circle. If it is an ellipse or irregular shape, it is more difficult for the driver to grasp the safe speed of the roundabout and should be avoided.

Turbine roundabout in Canada (Google image)

Kwong also said that in order to improve safety and reduce congestion, some places will add traffic lights to larger roundabouts to control traffic flow. This is also the case for the roundabout at Hoi Yuen Road in Kwun Tong.

He pointed out that the roundabout standards in European countries encourage the adoption of a tight layout to control the speed, and the use of single-lane vehicles as much as possible to improve safety.

In addition, the turbine-shaped roundabout developed by the Netherlands increases capacity while reducing conflict points and enhancing safety. "These three methods are worthy of local research."

Can pedestrians and bicycles use the roundabout safely?

Observe carefully, there will be no pedestrians on the roundabouts in Hong Kong. If pedestrians want to cross the road, most of them can only take a detour to take the footbridge.

Kwong Zixian explained that the general roundabouts in Hong Kong have a lot of traffic, with more than one lane, and the speed is too high, which is not suitable for pedestrian crossings.

To meet the needs of pedestrians crossing the road, he said, roundabouts can use single lanes, set up traffic lights, or set up deceleration platforms at crossings.

He mentioned that if traffic light crossings are set up, in order to avoid backflow of traffic, the crossings often deviate from the ideal pedestrian route, and large and busy roundabouts generally can only choose to set up pedestrian bridges or tunnels.

Large and busy roundabouts generally can only choose to set up pedestrian bridges or tunnels.

(Profile picture)

There have been many bicycle accidents in roundabouts in the past, and they often caused serious casualties.

Kwong Zixian said that when cyclists pass through the roundabout, they should pay special attention to the vehicles preparing to enter the roundabout. If the driver is not aware of the bicycles driving in the roundabout, or do not stop and give way.

He continued that if the layout of the roundabout allows vehicles to pass in a straight line, it is more dangerous; and the traffic flow at a roundabout with two or more lanes is more complicated and not suitable for cyclists to pass.

Roundabout = big traffic jam?

Road Research Agency: The mistake is that urban planning is most suitable for this type of place.

Roundabouts are difficult to get in and out, traffic accidents are frequent, Sai Kung has the most accidents last year

Outer circle and inner circle?

The roundabout is not clear for road fans: such as all drivers in Hong Kong playing Black Magic

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