Transport for Greater Manchester (TfGM) changed signal timings along Billinge Road on 11 September 2025. They wanted to understand and quantify how the change impacted weekday traffic and travel times, performing a before-and-after analysis.
Comparing date ranges in Path Analysis revealed that average speeds on approach to the signalised intersection increased from 6.3mph to 9mph, a 43% improvement. This meant even considering outliers, free-flow speeds had improved.
Chainage graph showing an increase in average speeds on approach to the intersection after signal change. Note: the pink line is before the signal change, and the blue line is after the change.
Trajectory analysis showed that before the signal change, only 26% of trips made no stops, while 16% made two or more stops. After the signal change, 36% of trips made no stops, and only 6% made two or more stops. This raw trajectory data is useful for identifying split failures.
Table showing the increase in free-flow traffic after signal change.
Speed and travel time improvements were consistent throughout the day, with a slight decrease during peak traffic at 5pm. However, after 5pm, speeds and travel times again improved, remaining higher than they had before the signal change, suggesting an unplanned event could be the cause of the dip. There was also a noticeable increase in vehicles travelling at higher speeds, particularly in the 12-19mph range and above.
Speed Analysis across hours of day shows that after the signal change, there is improvement in speeds except for a decrease in speeds at 5pm. Note: the pink line is before the signal change, and the blue line is after the change.
Travel times show that after the signal change, it takes less time to traverse the intersection. Note: the pink line is before the signal change, and the blue line is after the change.
Speed Bins show that after the change, there is an increase in the proportion of vehicles travelling at higher speeds through the intersection, and a decrease in the proportion of vehicles travelling at lower speeds. Note: the pink is before the signal change, and the blue is after the change.
Queue lengths along Billinge Road also decreased by up to 20 metres, confirming smoother and consistent traffic flow.
Before connected vehicle data, TfGM could generally tell if signal timings needed changing, and if the change was beneficial or not overall. Now, with this analysis, TfGM could quantify the impact and understand exactly how beneficial the change was for traffic along Billinge Road.