The data for these experimental statistics are taken from Trafficmaster in-vehicle global positioning systems (GPS) tracking data.
This is the latest release
As not every vehicle has these systems, it is likely that there are some unquantifiable biases in the data.
The speeds in this article are averages. They talk about the general speed over a period of months. On any particular day, incidents can occur which lead to speeds lower or higher than the average on different sections of the road.
This is the second statistical publication on speeds for roads in Wales.
- Over half the stretches of the A55 had average speeds of 60 mph or above, for either direction, during peak times and non-peak times.
- There were two parts of the A55 which frequently had average speeds of less than 30 mph. These sections are in Holyhead and around the Britannia Bridge crossing.
- Weekday average speeds on the A55 may have increased slightly in the two years between April to June 2014 and April to June 2016.
- During weekends, average speeds hit a low point at around 12:15 heading westbound, and at around 16:15 heading eastbound.
- Average speeds were slower in the morning peak on school days compared to school holidays.
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