What is the maximum speed allowed in tunnels E and F under STDS?

The maximum speed allowed in tunnels E and F under the Standards for Tunnel Design and Safety (STDS) is 40 MPH. This speed limit is established primarily for safety reasons, as tunnels present unique challenges such as restricted visibility, potential for congestion, and the need for emergency response accessibility.

In environments like tunnels, lower speed limits help ensure that vehicles have enough reaction time to respond to any unforeseen situations, such as a sudden stop or an emergency. Additionally, maintaining a maximum speed of 40 MPH aids in reducing the risks associated with collisions and helps to comply with ventilation and fire safety regulations, which are critical in enclosed spaces.

Importantly, while some tunnels might have higher speed limits under different conditions, STDS specifically designates 40 MPH for tunnels E and F based on an analysis of safety and traffic flow.