Traffic lights
Reykjavík City manages traffic lights in collaboration with the Road Administration and other municipalities in the capital area, divided into traditional intersection traffic lights and pedestrian crossing lights. Traffic lights are at 216 locations in the capital area.
Traffic lights consist of various units, including control boxes, light fixtures, sensors, and button boxes. The units are connected by cables in underground conduits and wells.
System objectives
- Adapt traffic light control to current traffic conditions.
- Give priority to Strætó Public Transport and emergency vehicles.
- Collect real-time traffic data and minimize traffic delays.
- Monitor and send automatic notifications for malfunctions.
Connection to centralized traffic control system
Over half of all traffic lights are connected to the centralized traffic control system (CTCS), a Sitraffic Scala system. The goal is to connect all traffic lights to the CTCS.
One advantage of connecting traffic lights to the CTCS is immediate malfunction notifications, allowing for quick responses.
Automation
The current system runs on automatic control called TASS. Its main benefit is selecting light settings based on current traffic volume for each TASS area.
The capital area is divided into five TASS areas:
- Sæbraut
- Miklabraut-Kringlumýrarbraut-Hringbraut-Suðurlandsbraut
- Hafnarfjarðarvegur
- Bústaðavegur
- Breiðholtsbraut-Nýbýlavegur
Traffic control
Traffic light control in the capital area is divided into three types:
- Pre-timed
- Semi-actuated
- Fully-actuated
Most traffic lights are traffic-controlled and operate based on sensors.
Pre-timed traffic lights have no sensors. The duration of green, yellow, and red lights is predefined and does not change based on traffic volume.
At semi-actuated intersections, the main direction stays green if no traffic is detected on side streets or if no one presses the pedestrian crossing button.
At fully-actuated intersections, all traffic streams show red if no road user is detected.
Green wave
A green wave occurs when traffic lights are synchronized so drivers can maintain a steady speed without encountering red lights. The steady speed is set at about 80-100% of the speed limit.
Green waves in both directions simultaneously are rarely possible due to intersection layout and location. Therefore, lights are synchronized for the dominant traffic direction at any given time. Traffic lights on main roads are synchronized to facilitate traffic flow towards the city center in the morning, away from the center in the afternoon, and outside peak hours.
The goal of traffic light synchronization is to improve traffic flow and minimize delays. However, various factors can affect synchronization, and its benefits are minimal during heavy traffic.
Priority for emergency vehicles and Strætó Public Transport
The central traffic control computer runs a priority system for emergency vehicles and Strætó Public Transport. Equipment in fire trucks and ambulances automatically requests priority at traffic lights when vehicles use emergency lights. Strætó Public Transport has easier passage through intersections with this control, though it's not priority control like for the fire department. For Strætó, a device in the bus detects when it approaches an intersection and extends the green light duration in the bus's direction.
The priority system aims to ensure increased safety in emergency driving, both for those in emergency vehicles and for general traffic affected by emergency driving. It's also crucial to reduce response time when people are in life-threatening situations, especially during heavy traffic. The system has proven very effective.
Counting locations
Collecting traffic information is fundamental to centralized traffic control. Traffic sensors have been installed at several counting locations to detect and assess traffic volume. The sensors are connected to the CTCS, where information from sensors is used to select the most suitable light program at any given time.
Real-time information on the service level of the traffic flow
Real-time information about traffic volume and speed at selected locations
Control box types
The control box manages traffic lights and consists of several units. All light fixtures, button boxes, and sensors connect to the control box, and its safety system ensures proper traffic light function and correct response to disruptions.
Traffic lights are continually being renewed, with eight different types of control boxes in use, some over 30 years old. During renewal, connecting traffic lights to the CTCS is a priority to enable monitoring and quick response to malfunctions.
Light fixture types
Only LED lights are used when renewing traffic lights. In addition to being energy-efficient, LED lights are much more reliable and have a lower failure rate than traditional incandescent bulbs. More than half of traffic lights use LED lights.
Page updated 5/6/2024