Request:
“I was informed in an email from Devon Highways that the average speeds on the B3178 through Knowle Village are 34mph eastbound and 33.5mph westbound.
I would like to know what the highest recorded speed and the lowest recorded speed is eastbound, and what the highest and lowest recorded speeds are westbound for this road which are being used to calculate these average speeds of 34 and 33.5mph.
I would also like to know which exact sources have provided this speed data. Is there data from Devon Highways speed monitoring, is there data from the police, is there another party providing speed monitoring data, or does the data creating these recorded average speeds of 34mph and 33.5mph come from the Knowle Village Traffic Group? If the data is from multiple sources, could you clarify towards which organisation the data weighs.”
Response:
Firstly, please note that our max/min speed data generally records vehicle speed into 5mph ‘bins’ up to 70mph, although the first ‘bin’ records any vehicles travelling less than 15mph, and last ‘bin’ records any vehicles travelling at or over 70mph, so the precise speeds of any individual vehicle is not recorded.
Our data indicates:
East bound – max speed >70mph, min speed <15mph
West bound – max speed 65-70mph, min speed <15mph
Source of data: Devon Highways
To put into context the survey was carried out over a 9 day period in November 2011 and recorded 45,000 vehicles of which 2 are indicated as travelling at over 70mph. Furthermore It should be noted that the vehicles travelling at the highest speeds are often motorcyclists or emergency vehicles and that these do not represent the speeds of most traffic. It is an unfortunate fact that there will always be a few vehicles travelling faster than they should. Similarly slow moving vehicles, such as farm machinery and construction/maintenance machinery do not represent most traffic, and this is why averages are used by most authorities looking at the speed of traffic.