GRT Traffic Impact

Contents

• Traffic impact of BRT
• Mixed traffic operation through constrained points

Traffic impact of BRT

BRT will not worsen the performance of mixed traffic in Zhongshan Av,. Instead, BRT will have a major positive impact on the mixed traffic along the BRT corridor, especially in Zhongshan Av. The buses being withdrawn from general traffic and taken into the BRT lanes account for up to one third of all the traffic in the western part of the Zhongshan Av corridor. In Zhongshan Av between 体育中心 and 岗顶 the travel speed for mixed traffic will increase from 12 km/hr to more than 30 km/hr. This positive impact comes from signal phase changes as well as the huge traffic impact of withdrawing more than 400 buses per hour from the mixed traffic lanes in this location.

The figure below shows the total number of buses on Zhongshan Av, and the share of them that can be reallocated to the BRT system. The proportion of buses captured inside the system is excellent in the Zhongshan corridor (averaging 88% of buses for each station).

Mixed traffic operation through constrained points

The standard BRT configuration can be applied to most of the Zhongshan Avenue corridor. However, particularly at flyovers, there are some points where the standard configuration has to be modified. For flyovers the generally favoured option for Phase I is to end the BRT lane and operate in mixed traffic. This approach has been applied on Zhongshan Av at Wushan Rd and the Huanan Expressway.

Although it is possible to simply terminate the BRT lane around 50m before the bottleneck without any special control, a better approach is to install a special traffic light signal to control congestion on the grade separated section (or bridge or other restricted point). This signal is based on average occupancy of the controlled link, and is especially useful even without bus lanes to avoid congestion and related excessive air pollution in tunnels. The general approach is illustrated below. This device is known as a congestion control signal or CCS.