CONNECT E-newsletter logo

GLIDE Into Smoother Traffic: The Green Wave You Want to Ride

Posted on | 28 Mar 2024

That’s the one that lets you sail through traffic junctions with every light in your favour. Is it for real? Here’s your guide to GLIDE!

Image of family in car, with title "GLIDE Into Smoother Traffic" in the background

Tapping on technology to surf the roads smoothly isn’t stuff of the future. LTA’s Green Link Determining System (GLIDE) aims to make your commuting dreams come true.

How does GLIDE work?
Infographic showing how GLIDE works with two cars on road apart

The GLIDE system adjusts the timing of the green light at traffic junctions as traffic flow changes. It allows adjacent traffic signals to sync up in such a way that your number of stops is minimised.

GLIDE’s principal purpose is to minimise the overall delay for all commuters. When traffic builds up, the lights adjust to maximise throughput and minimise jams. If you are travelling along major corridors and arterial roads, you might have noticed the difference! Waving you through is one of the aims of the system.

The evolution of linked traffic lights

As it turns out, the idea of a “green wave” for traffic isn’t new at all! In fact, this has been a work in progress for decades.

Early 1970s:

The first 36 traffic signal controllers were linked by cables laid under footpaths, to create a couple of “corridors”. Two pairs of one-way streets were connected to a master electromechanical controller and worked using an assumed vehicle speed and a fixed cycle time*.

Late 1970s:

Microprocessor controllers were the latest tech! With no more need for physical cables to connect the traffic lights, more corridors could be linked. Controller clocks were synchronised to cue the green lights, but tended to drift out of sync. 

Early 1980s:

Area Traffic Control was installed, taking advantage of existing telephone cables to link a central computer to 181 traffic signals. This fixed the drifting clock cycle problem and the control centre could manage and monitor the lights, but it couldn’t cope with changing traffic conditions. If a jam built up because of road works or an accident, you’d still get stuck.

Fun fact!

Did you know? Green lights used to be fixed at 85 seconds. Now the timing depends on the traffic flow. Priority is given to the direction with the higher volume of traffic, allowing for smoother traffic flow for all motorists.


SCATS (Sydney Coordinated Adaptive Traffic System) was adopted to replace the fixed time system and given the name GLIDE in Singapore. Wire loops implanted 25mm under the road surface near the stop line detect vehicles, counting both their number and the gap in time between successive ones. GLIDE then works out the optimal cycle times to keep traffic moving and allocates green time accordingly.

Fun Facts: All About the GLIDE System
Infographic showing how GLIDE works with two cars on road apart
1. Which roads in Singapore currently use GLIDE?

All of them! Today, every traffic signal on the island is controlled by GLIDE — that’s about 2,700 intersections. A regional computer controls up to 250 intersections. With 18 regional computers on the job, we can potentially manage 4,500 junctions!

A central computer monitors the operation of each regional computer.

2. Is the green wave adjusted in real time?

Yes. GLIDE is at work 24/7!

3. Does it break the chain when someone activates a pedestrian crossing?

No. Pedestrian lights are part of the GLIDE network. If no one presses the crossing button, the lights won’t change—this way motorists won’t be caught at an unnecessary stop.

Infographic showing fun facts about our traffic system known as GLIDE
4. If there is a green wave, would there also be a red wave for unlucky motorists?

The green wave favours the heavier traffic flow, for example city-bound traffic in the mornings and home-bound roads in the evening. If you’re headed the other way, your best bet to catch a wave is to keep with the main stream of vehicles, as GLIDE factors in the gaps in the flow. If you’re too far ahead or behind, you won’t be “counted” and miss the wave!

5. Then is there a particular speed I should be driving at in order to stay on the “wave”?

Nope, GLIDE looks at how heavy the traffic is, not how fast it is going, when it computes how to allocate green time. Like we said, stick with the crowd and just go with the flow!

Motorists should always observe speed limits when driving and follow driving safety rules.

Pedestrian signals: A couple of neat things to know
Image of "Wave for Green Man" signage

Wave to cross

Just a wave of your hand is enough to activate the green man at some pedestrian crossings in a trial to do away with buttons. This greatly reduces wear and tear of the push buttons, which tend to attract vandalism and abuse. (That’s the repeated pressing that some folks do. Once it’s been pressed, the call for the Green Man light is triggered. Pushing it again, or harder, doesn’t make the light change any faster!)

Hear ye, hear ye

As part of the Enabling Masterplan 2030, round-the-clock on-demand audible traffic signals will be installed to help the visually impaired cross safely in 10 town centres.

Audio devices on pedestrian lights emit an intermittent, soft locating tone that aids persons with visual impairment in identifying a crossing. Then, when the green man is on, the heightened tone which we are all familiar with sounds to indicate that it is time to cross. The roll-out is slated for completion by 2025.

Already, some 1,300 traffic signals, representing 20% of all signalised pedestrian crossings, are now equipped with these devices!

Liked this CONNECT article? Share this with your family and friends so they can catch the next green wave!
Scroll To Top

Welcome to


This quick tour will bring you through the key enhancements.

Use the links at the top navigation bar to help you find what you are looking for

Tutorial Menu Tutorial Menu Tutorial Menu

Jump straight into the popular pages that

are most relevant to you

Tutorial Popular Resources Tutorial Popular Resources Tutorial Popular Resources

Taking a bus, train, or cycling to your

destination? Plan your routes and check

the fares using these tools!

Tutorial Transport Tools Tutorial Transport Tools Tutorial Transport Tools

Our latest featured projects are just a click away!

Tutorial Featured Projects Tutorial Featured Projects Tutorial Featured Projects

Start exploring


Explore Now!