Tamki Bridge Motorcycle Lane Width Sparks Debate, Scholars Urge Observation Before Reassessment

There is public questioning about the narrowness of the Tamki Bridge's motorcycle lane, which has a width of 2.5 meters. Some citizens have expressed concerns that a minor accident could lead to chain collisions or impede emergency vehicle passage. In response to these concerns, various suggestions have been proposed, including widening the motorcycle lane, converting it to a mixed traffic lane for cars and motorcycles, or declassifying the Tamki Bridge as a regular provincial highway. The Northern Region Second Engineering Office of the Directorate General of Highways, Ministry of Transportation and Communications, explained on April 19th that according to the Highway Route Design Standards, lane width should be a minimum of 2.5 meters for roads with separated designs outside the shoulder. The Tamki Bridge motorcycle lane features physical separation and a width of 2.5 meters, complying with the standards. As the Tamki Bridge is part of Provincial Highway No. 61 (an expressway), separated designs are required outside the shoulder, thus adopting dedicated lanes for motorcycles. Professor Cheng Yung-hsiang of the Department of Transportation Management Science at National Cheng Kung University stated in an interview with CNA that the 2.5-meter width for the motorcycle lane indeed conforms to regulations. Future traffic engineering and management improvements should be based on data observed after the bridge opens, considering factors such as peak and off-peak traffic flow, speed, density, and accident rates, followed by a comprehensive professional assessment for any adjustments. He suggested observing for three months to half a year, or even a year, after opening before making an evaluation. Professor Wu Kun-feng of the Department of Transportation and Logistics Management at National Yang Ming Chiao Tung University urged the public not to jump to conclusions about improvements, calling for the Public Works Department to explain its initial traffic flow projections for cars, heavy vehicles, and motorcycles, and the rationale behind the current configuration, allowing society to review the reasonableness of its design. Wu Kun-feng pointed out that no one wants accidents on the bridge, but if an accident occurs in a dedicated motorcycle lane, whether there are mechanisms to guide traffic flow through it is crucial. If supporting measures are lacking, motorcycles might be completely trapped in the lane. He cited examples of accidents on expressways where a section is cordoned off or 2-3 lanes are closed, allowing other vehicles to pass slowly. The main bridge of the Tamki Bridge is approximately 920 meters long, with a main span of 450 meters, making it the world's longest single-pylon asymmetrical cable-stayed bridge, designed by the office of internationally renowned architect Zaha Hadid. Upon completion, the Tamki Bridge will be designated as Provincial Highway No. 61 and will serve as the starting point of the Provincial Highway No. 61 West Coast Expressway. The bridge deck is symmetrically designed for northbound and southbound traffic. From the outermost to the innermost lanes, it is planned with pedestrian walkways, bicycle lanes, and motorcycle lanes, each 2.5 meters wide. Car and large vehicle lanes are designed as double lanes, each 3.5 meters wide, with a central bus-only lane (future light rail) of 3.25 meters. Among the attached motorcycle lanes on expressways managed by the Public Works Department, the dedicated motorcycle lane on Provincial Highway No. 65 crossing the Dahan River has the same width of 2.5 meters as the Tamki Bridge.