EMAS lane-use and variable message signs

Display types

TTDs are placed at entrances leading to expressways and show estimated travel times from that point to selected exits. The handbook uses green for estimates up to 50% more than normal travel time, yellow for estimates between 50% and 125% more, and red for estimates more than 125% of normal travel time. A TTD may also show an incident message and the direction of the incident (SPF, Basic Theory of Driving).

TIDs are large displays along expressways and selected major arterial roads. They use text and simple graphics, with up to seven colours, to report conditions ahead. The handbook describes a red cross as marking the incident location by reference to labelled expressway exits or major roads, and a flashing red bar as indicating a road closure ahead. TIDs may show an incident type, affected lane, congestion, travel-time information, or another traffic advisory. Smaller TSDs are generally on expressway centre dividers; they use symbols to indicate adverse conditions or instruct motorists to change lanes (SPF, Basic Theory of Driving).

Lane-use symbols

• a red cross, meaning the lane is closed;
• a flashing amber cross, meaning there may be an obstruction ahead: slow down and prepare to change lane;
• a green arrow, indicating that the lane is open;
• caution, congestion, accident, vehicle breakdown, or roadworks symbols, which tell motorists to slow down and drive carefully;
• recommended speed, indicating the recommended speed to drive;
• must exit, meaning the expressway is closed ahead and the driver should exit;
• exit closed ahead, meaning use an alternative exit; and
• lane reduction, meaning there is an obstruction at the indicated lane: slow down, drive carefully, and get ready to change lane if necessary (SPF, Basic Theory of Driving). The handbook also illustrates ambulance and fire-engine symbols, which instruct motorists to look out and give way to those vehicles (SPF, Basic Theory of Driving).

The handbook says expressway lanes are numbered in ascending order from the fast lane to the slow lane, excluding the road shoulder (SPF, Basic Theory of Driving).

In the KPE, CTE, MCE, Woodsville, and Fort Canning tunnels, overhead Lane Use Signs show a green downward arrow, flashing amber cross, or red cross. The green arrow means a motorist may proceed; the amber cross means proceed cautiously, for example because of an obstruction; the red cross means do not proceed beyond the sign. LTA also tells tunnel drivers to follow overhead lane-use signs and traffic-message signboards; in a tunnel emergency, do not proceed into a lane displaying a red X (SPF, Basic Theory of Driving; LTA OneMotoring, Driving on Expressways & in Tunnels).

The handbook identifies three tunnel message-sign locations: Entrance Variable Message Signs at the entrance to a tunnel slip road; Arterial Variable Message Signs along an arterial road leading to a tunnel; and Tunnel Variable Message Signs overhead inside the tunnel. It says barriers and traffic-signal controls at entry slip-road approaches will be activated when the KPE, MCE, or Woodsville tunnel is closed. Variable speed signs in the KPE and MCE display a posted speed limit with a red ring in smooth traffic, which motorists must obey; during congestion they may display a lower recommended speed without a red ring to smooth traffic flow and reduce risks (SPF, Basic Theory of Driving).

For tunnel breakdown, accident, fire or smoke, and evacuation procedures, see Expressway and tunnel rules. LTA's current Driving on Expressways & in Tunnels page is live and provides those emergency steps.

Coverage debt

• The handbook and LTA page provide examples but not a complete machine-readable display or symbol index. This guide does not infer meanings for symbols beyond those described in the cited material.

Sources

• SPF, Basic Theory of Driving
• LTA OneMotoring, Driving Rules and Information
• LTA OneMotoring, Driving on Expressways & in Tunnels