The Taiwan Transportation Safety Board (TTSB) released the final report on the investigation of a Chien Chuan Tourist Bus Hit the Inner Lane Guardrail and Collided with a Passenger Car on Gukeng Section of National Highway No.3.

On October 21, 2023, at 09:42 a.m., a commercial tourist bus owned by Chien Chuan Transportation Co., Ltd. (hereinafter referred to as Chien Chuan Transportation) carrying 42 individuals, i.e., 1 driver, 1 tour guide, and 40 passengers collided with a passenger car on the right at 263K+788 on the southbound of Freeway No. 3 (Gukeng section, speed limit 110 km/hour). The passenger car, carrying one passenger and one driver, was pushed to the outer guardrail. The rear right of the bus crashed into the outer guardrail and noise barrier wall. The occurrence resulted in 4 fatalities, 2 serious injuries and 20 minor injuries in the 2 vehicles.

In accordance with the Transportation Occurrence Investigation Act, the Taiwan Transportation Safety Board (TTSB) is the independent transportation occurrence investigation agency responsible for conducting the investigation. The investigation team also included members from the Highway Bureau, the Freeway Bureau, Chien Chuan Transportation Co., Ltd., TIU Group Members (Backpack Vacation), Daimler Trucks Asia Taiwan Ltd., and the Vehicle Safety Certification Center.

The draft for this investigation report was completed in January 2025. It was revised after preliminary review at the 72nd Board Meeting of the TTSB on February 14, 2025, according to procedures, and then sent to relevant agencies (institutions) for their opinions. After summarizing relevant opinions, the investigation report was approved in the TTSB’s 73rd Board Meeting on March 14, 2025.

After a comprehensive investigation and analysis of the factual data, 13 findings and 4 safety recommendations were obtained.

Investigation Findings

Findings Related to Probable Causes

1. The driver's workload on the previous day was higher than usual. This curtailed his rest time the previous night, with merely four hours of sleep, and resulted in short-term sleep deficiency. Meanwhile, the driver may also be subject to the side effects of medication. The driver experienced a brief lapse in attention and was unable to open his eyes for a few seconds prior to the occurrence, which rendered him unable to focus on the road environment and the operation of the vehicle. This resulted in the bus, while flashing the right turn signal, veering from the outer lane into the inner lane and subsequently colliding with a passenger car before crashing into the inner guardrail.
2. Upon the first collision, the driver may have been unable to promptly identify the surrounding environment and the positions of other vehicles and take the appropriate action. Instead, he oversteered the bus to the right, causing it to tilt significantly leftward. The bus traveled at an angle of approximately 45 degrees toward the outer lane and crashed into a passenger car. Subsequently, the front of the bus crashed into the outer guardrail, while the rear, due to rightward inertia, crashed into the outer guardrail and noise barrier wall, resulting in the deaths of two bus occupants.

Findings Related to Risks

1. Chien Chuan Transportation failed to properly arrange the regular driver assignment schedule, causing the driver’s rest time to only meet the minimum regulatory requirements. The driver was subsequently given additional assignments, which led to his rest time falling below 10 hours. This demonstrates the deficiencies in Chien Chuan Transportation's management of the driver assignment schedule, particularly its failure to ensure adequate rest time for the driver.
2. Chien Chuan Transportation was unable to identify the drivers by using GPS to supervise their fleets. The company also failed to supervise the use of vehicles and the assignment of drivers accurately when compiling the driver assignment schedule. It is difficult to detect a driver who switches assignments, such as the driver in the occurrence who had undertaken assignments for 13 consecutive days. This indicates that improvements are needed in Chien Chuan Transportation’s driver scheduling practices.
3. Under the Highway Bureau's existing supervision mechanism, the system operated by the Vehicle Dynamic Information Management Center is unable to detect drivers who have taken less than 10 hours of rest between two consecutive workdays.
4. The height of the last row of passenger seats on the bus is nearly level with the bottom edge of the window frame. In the event of a side impact involving a bus similar to the one in the incident, the window glass may shatter, potentially leaving the passenger’s upper body exposed and unprotected.
5. The bus's window glass shattered upon impact. Despite the two-point lap belt being securely fastened, the body of a passenger on the right side in the last row was partially ejected when the bus collided with the noise barrier wall. The passenger could have been more securely seated if a three-point belt had been used, which could have prevented the passenger from being ejected from the vehicle during the collision or the rollover.

Other Findings

1. The vehicle had a valid vehicle license issued by the Highway Bureau, MOTC. According to the inspection results, no abnormalities were found in the chassis, engine, braking system, tire tread depth, or tire pressure of the bus. It was sunny, and the visibility was good at the time of the occurrence. No abnormalities were found on the pavement. The driver held a valid driving license issued by the Highway Bureau and had completed the required periodic training for professional drivers of large passenger vehicles. Following the occurrence, the residual space of the bus structure was intact. The frame of the vehicle suffered no evident damage.
2. The driver worked a total of 12 hours on the previous day, with 9 hours of driving time, which was in line with regulatory requirements. However, he had fewer than six hours of rest, which violated Article 19-2 of the Regulations for Automobile Transportation Operators, where drivers working two consecutive days shall have 10 consecutive hours of rest time.
3. The driver admitted to taking one capsule of Sonaplon and one tablet of Mocalm Tab prior to the occurrence. Nevertheless, available evidence indicated that the connection between the driver's medication, his symptoms, such as a brief lapse in attention and temporary eye closure, had low relevance.
4. The investigation team was unable to verify whether the driver had taken medication containing Benzodiazepines; however, the possibility could not be excluded. Side effects of sedatives containing benzodiazepine include lapses in attention, which is in line with the lapses in attention, and temporary inability to open his eyes, as described by the driver. However, following the occurrence, the urine sample analysis did not include the details of the dosage and composition. Furthermore, the side effects experienced may vary depending on individual sensitivity and whether the medication was used for the first time or on a long-term basis. Therefore, the extent to which any residual benzodiazepine in the driver’s system may have affected his ability to operate the bus could not be determined. Nonetheless, taking medication containing benzodiazepines may increase the safety risk of operating a bus.
5. The laminated glass installed in the bus was in line with the provisions of the Vehicle Safety Type Approval Management Regulations. Nevertheless, when the bus collided with the outer guardrail and noise barrier wall, the impact force significantly exceeded the strength that the glass was designed to withstand, causing the window glass to shatter and form openings through which passengers could be exposed.
6. According to research by the United Nations Economic Commission for Europe, seat belts and window protection or side panels should be installed at shoulder level to prevent passengers from being ejected from their seats or out of the vehicle. In the event of a rollover incident, the dipping angle of a passenger in a three-point belt is lower than that of a two-point lap belt. Therefore, a three-point belt is able to make passengers better restrained in their seats and reduce the risk of passenger ejection during an impact or rollover.

Safety Recommendations

To Chien Chuan Transportation Co., Ltd.

1. Implement a driver management system. When a driver is found to have inadequate rest time, Chien Chuan Transportation should proactively assign a qualified replacement driver to take over the assignment. Chien Chuan Transportation should ensure that drivers are given sufficient rest time and have enough sleep pursuant to regulatory requirements, and accurately monitor and arrange driver assignments.

To the Highway Bureau, MOTC

1. Strengthen the management of tourist bus driver scheduling and prevent instances in which drivers' rest time between two consecutive working days does not meet the legal requirements.

To the Ministry of Transportation and Communications

1. Promote the installation of driver identification systems on tourist buses to enhance the management of driving time and rest time by transportation companies and supervision agencies.
2. Strengthen the safety protection of bus passengers to prevent the ejection of passengers from the vehicle and reduce the risk of injury or fatality in the event of an accident.

Ya-Ting Chang, Secretariat Office

Tel: +886-2-7727-6210

E-mail: yating@ttsb.gov.tw

Jen-Sung Tseng, Chief Investigator

Highway Occurrence Investigation Division

Tel: +886-2-7727-6270

E-mail: jstseng@ttsb.gov.tw