Summary of Speed Indicator Device (SID) Activity
For the Period 29th September to 3rd December 2020
Location : During this period the SID was positioned on the Homington Road next to Tottens Farm, which is a 20 mph speed limit area. The SID was mounted on a relocatable post on the left-hand side of the road as you leave Coombe Bissett village heading towards Homington. This site is referred to as the Homington Road, Tottens Farm site.
For more information regarding approved SID sites in Coombe Bissett and Homington villages please refer to the SID location Power Point guide.
For more information regarding approved SID sites in Coombe Bissett and Homington villages please refer to the SID location Power Point guide.
Detailed PDF reports:
Please refer to the tab for Tottens Farm for more detailed analysis of traffic data recorded by the SID, which is presented in PDF report format. Guidance Notes to each section of the PDF reports are provided below this summary.
Note: Our SID does not have GPS and therefore its reports are location agnostic. References in reports to Incoming and Outgoing traffic refer to traffic coming towards the device (Incoming) and traffic going past the device in the opposite direction (Outgoing).
Period 29th September – 19th October 2020
During this period the SID was facing traffic coming from Homington and Nunton. The average speed of drivers entering the village was 24.85 mph while traffic leaving the village travelled at an average of 28.19 mph. The Highest speed recorded for drivers entering the village was 65 mph and for drivers leaving the village was 96 mph. Vehicle volumes during the period were approx. 364 per day in either direction. 63.96% of drivers were travelling within 26 mph as they entered the village, while only 45.43% were travelling at less than 26 mph at this point as they were leaving the village. The recorded speed of the 85th percentile of vehicles was 32 mph inbound and 34 mph outbound. Based on this information, Police enforcement is warranted for inbound and outbound traffic at these speeds.
NB: It has since been established that the detection range of the SID is up to 200 metres and that the device was therefore detecting vehicles while they were still in the 50 mph speed limit area. As a result, the report for this period does not accurately reflect the speed of traffic once it was within the 20 mph limit area. Following consultation with the manufacturer, the SID will need to be adjusted so that its detection range is reduced when it is located at the same site and pointing in the same direction, in future.
Period 23rd October - 4th November 2020
The SID sign was then turned around so that drivers heading out of the village could now see their speeds displayed by the SID. The detection range was entirely within the 20 mph speed limit zone. Please note that references in PDF reports to ‘incoming’ refer to traffic approaching the SID while ‘outgoing’ refers to traffic passing in the opposite direction. Drivers leaving the village were travelling at an average speed of 22.18 mph while those entering averaged 24.4 mph. Maximum speeds were 56 mph leaving the village and 64 mph entering the village. Vehicle volumes were lower, averaging 283 per day leaving the village and 295 entering. While the period covered the start of the second lockdown, the reduction in volumes is also affected by the shorter reporting period including two weekends. This highlights fact that the majority of drivers using this road are week-day users (commuters, people at work or school-run drivers). The percentage of outbound drivers travelling at 26 mph or less increased to 81.86% and the percentage of drivers entering the village at speeds of up to 26 mph was 68.29%. The recorded speed of the 85th percentile of drivers who could see the sign was 27 mph. The equivalent statistic for outbound drivers was 29 mph. Any 85%ile speed higher than 24.1 mph is still too high for a 20 mph zone and warrants Police enforcement.
Period 8th November – 3rd December 2020
The SID was rotated again so that it was now back facing traffic entering the village from Homington and Nunton. The anomaly regarding the detection range had yet to be identified at this time. The average speed of drivers entering the village was 23.83 mph, while drivers leaving the village averaged 27.86 mph. Maximum speeds were again much higher than the preceding period, since the SID was detecting vehicles in the 50 mph zone. Traffic volumes during this period increased slightly but remained below the initial statistics for this site, possibly as a result of lockdown restrictions. The percentage of drivers entering the village at speeds below 26 mph was 70.26%. Without the deterrent of the SID, the percentage of drivers leaving the village below 26 mph was 47.44%. Both statistics are a marginal improvement over the initial period notwithstanding the anomaly of the SID’s detection range in this position. The 85th percentile speed indicator improved marginally for incoming traffic.
The period from 23rd October to 4th November is the most accurate reflection of traffic speeds at this location according to SID data. We will ensure to modify the SID’s detection range so that in future, speeds are recorded accurately at this site regardless of the direction in which the SID is facing.
The SID was at this site for a total of 66 days which was much longer than anticipated. It was not, however, possible to relocate the SID once the second lockdown commenced. The SID nevertheless provided a means of controlling traffic speeds on the Homington Road at Tottens Farm during lockdown. It should be noted that CSW speed checks at this location consistently record the highest number of speeding and excessively speeding drivers per total number of vehicles of all CSW sites in our community.
The Coombe Bissett Community Speed Watch (CSW) team continued to conduct speed checks up until 4th November 2020 following which activity was suspended due to the second lockdown. We are pleased to advise that CSW checks have resumed and we have 3 checks scheduled for the week commencing 14th December 2020.
Please refer to the tab for Tottens Farm for more detailed analysis of traffic data recorded by the SID, which is presented in PDF report format. Guidance Notes to each section of the PDF reports are provided below this summary.
Note: Our SID does not have GPS and therefore its reports are location agnostic. References in reports to Incoming and Outgoing traffic refer to traffic coming towards the device (Incoming) and traffic going past the device in the opposite direction (Outgoing).
Period 29th September – 19th October 2020
During this period the SID was facing traffic coming from Homington and Nunton. The average speed of drivers entering the village was 24.85 mph while traffic leaving the village travelled at an average of 28.19 mph. The Highest speed recorded for drivers entering the village was 65 mph and for drivers leaving the village was 96 mph. Vehicle volumes during the period were approx. 364 per day in either direction. 63.96% of drivers were travelling within 26 mph as they entered the village, while only 45.43% were travelling at less than 26 mph at this point as they were leaving the village. The recorded speed of the 85th percentile of vehicles was 32 mph inbound and 34 mph outbound. Based on this information, Police enforcement is warranted for inbound and outbound traffic at these speeds.
NB: It has since been established that the detection range of the SID is up to 200 metres and that the device was therefore detecting vehicles while they were still in the 50 mph speed limit area. As a result, the report for this period does not accurately reflect the speed of traffic once it was within the 20 mph limit area. Following consultation with the manufacturer, the SID will need to be adjusted so that its detection range is reduced when it is located at the same site and pointing in the same direction, in future.
Period 23rd October - 4th November 2020
The SID sign was then turned around so that drivers heading out of the village could now see their speeds displayed by the SID. The detection range was entirely within the 20 mph speed limit zone. Please note that references in PDF reports to ‘incoming’ refer to traffic approaching the SID while ‘outgoing’ refers to traffic passing in the opposite direction. Drivers leaving the village were travelling at an average speed of 22.18 mph while those entering averaged 24.4 mph. Maximum speeds were 56 mph leaving the village and 64 mph entering the village. Vehicle volumes were lower, averaging 283 per day leaving the village and 295 entering. While the period covered the start of the second lockdown, the reduction in volumes is also affected by the shorter reporting period including two weekends. This highlights fact that the majority of drivers using this road are week-day users (commuters, people at work or school-run drivers). The percentage of outbound drivers travelling at 26 mph or less increased to 81.86% and the percentage of drivers entering the village at speeds of up to 26 mph was 68.29%. The recorded speed of the 85th percentile of drivers who could see the sign was 27 mph. The equivalent statistic for outbound drivers was 29 mph. Any 85%ile speed higher than 24.1 mph is still too high for a 20 mph zone and warrants Police enforcement.
Period 8th November – 3rd December 2020
The SID was rotated again so that it was now back facing traffic entering the village from Homington and Nunton. The anomaly regarding the detection range had yet to be identified at this time. The average speed of drivers entering the village was 23.83 mph, while drivers leaving the village averaged 27.86 mph. Maximum speeds were again much higher than the preceding period, since the SID was detecting vehicles in the 50 mph zone. Traffic volumes during this period increased slightly but remained below the initial statistics for this site, possibly as a result of lockdown restrictions. The percentage of drivers entering the village at speeds below 26 mph was 70.26%. Without the deterrent of the SID, the percentage of drivers leaving the village below 26 mph was 47.44%. Both statistics are a marginal improvement over the initial period notwithstanding the anomaly of the SID’s detection range in this position. The 85th percentile speed indicator improved marginally for incoming traffic.
The period from 23rd October to 4th November is the most accurate reflection of traffic speeds at this location according to SID data. We will ensure to modify the SID’s detection range so that in future, speeds are recorded accurately at this site regardless of the direction in which the SID is facing.
The SID was at this site for a total of 66 days which was much longer than anticipated. It was not, however, possible to relocate the SID once the second lockdown commenced. The SID nevertheless provided a means of controlling traffic speeds on the Homington Road at Tottens Farm during lockdown. It should be noted that CSW speed checks at this location consistently record the highest number of speeding and excessively speeding drivers per total number of vehicles of all CSW sites in our community.
The Coombe Bissett Community Speed Watch (CSW) team continued to conduct speed checks up until 4th November 2020 following which activity was suspended due to the second lockdown. We are pleased to advise that CSW checks have resumed and we have 3 checks scheduled for the week commencing 14th December 2020.
NOTE EXPLAINING INFORMATION IN PDF REPORTS
OF SPEED INDICATOR DEVICE (SID) ACTIVITY
COVER PAGE
The start and end dates for the period the device has been active at a location are shown on all pages.
Location: Records where the SID device was positioned during the report period and is shown on all pages.
Note: The Parish Council agreed that the SID should serve as much of the community as possible. Sites have had to be agreed by Wiltshire Council. At present there are a total of 7 approved sites. Details of exactly where each site is located are available in a separate document.
Comments: Details here show the speed limit for the site where the SID was located and the direction of traffic the SID was monitoring at that location:
- Inbound relates to traffic coming into the village
- Outbound relates to traffic leaving the village
The Comments section also states whether the sign was actively displaying the speed information to oncoming traffic or if it was in ‘Spy Mode’. Spy Mode records traffic information but does not display speeds, and is used to baseline traffic speeds at the start of the period.
PAGE TWO: AVERAGE SPEEDS
The Average Speeds graph includes two averages:
- An ‘average by time period’, which is displayed as a curve on the graph. (one curve per direction: ingoing/outgoing).
- An overall average which is displayed as a numeric value just below the graph.
The ‘average by time period’ corresponds to the arithmetic average calculated on the speeds recorded between the start/end dates. They are presented on a default time period of 30 minutes. The overall average corresponds to the arithmetic average of all the speeds included between the starting/ending dates on the time period selected for the PDF report. The software sums up all of the recorded speeds, then divides the result by the number of vehicles measured.
Note: References in the PDF report to Incoming direction and Outgoing direction relate to the direction of traffic in relation to the SID. ‘Incoming’ relates to traffic heading towards the device. ‘Outgoing’ relates to traffic going past the device in the opposite direction
PAGE THREE: MAXIMUM SPEEDS
Similar to the information for average speeds, the graphs relating to maximum speeds are displayed in curve and number format.
- The maximum speed recorded per time period are displayed in graph form (oncoming and outgoing are reflected in different colours).
- The maximum speed recorded over the entire time period is shown for each direction as a numeric value just below the graph.
PAGE FOUR: VEHICLES PER HOUR
Graphs show traffic volumes for incoming traffic (Green) and outgoing traffic (Blue) for each 24-hour period covered by the report. Total volumes are shown at the top right of the graph
PAGE FIVE: SPEED DISTRIBUTION FOR INCOMING TRAFFIC
PAGE SIX: SPEED DISTRIBUTION FOR OUTGOING TRAFFIC
In these sections, the recorded speeds are represented in pie chart form, and allow you to see the percentage of vehicles which have, or have not, observed the speed limit.
The first segment shows the percentage of vehicles which are travelling below or at the legal speed limit in that location. The second segment shows the percentage of vehicles which are travelling above the legal limit but approximately within the speed tolerances permitted by Wiltshire Police and Community Speed Watch before drivers may be sanctioned. The remaining segments show the percentage of vehicles travelling at excessive speeds.
PAGE SEVEN: PERCENTILES FOR INCOMING TRAFFIC
PAGE EIGHT: PERCENTILES FOR OUTGOING TRAFFIC
The 85th percentile is an indicator that helps illustrate the behaviour of the majority of drivers. It reflects the speed respected by 85% of motorists and is obtained by stripping out the bottom and top & bottom 7.5% of speeds recorded (i.e. strips out the extremely fast and extremely slow vehicles).
If the 85% threshold is close to the average speed recorded, this indicates that the speeds observed on a road are consistent. If it is not close to the average speed, this means that a significant proportion of drivers are above the average recorded speed.
Note: Wiltshire Police use 85th Percentile speeds to determine whether they should conduct their own Speed Checks in any location. This is normally determined by the use of a Traffic Speed Survey which is sometimes referred to as a Metro Count. It involves two rubber strips placed across the road connected to a recording device. To-date, the Parish Council have had to request Speed Traffic Survey reports on a case by case basis, before any Police enforcement action will be considered.
The start and end dates for the period the device has been active at a location are shown on all pages.
Location: Records where the SID device was positioned during the report period and is shown on all pages.
Note: The Parish Council agreed that the SID should serve as much of the community as possible. Sites have had to be agreed by Wiltshire Council. At present there are a total of 7 approved sites. Details of exactly where each site is located are available in a separate document.
Comments: Details here show the speed limit for the site where the SID was located and the direction of traffic the SID was monitoring at that location:
- Inbound relates to traffic coming into the village
- Outbound relates to traffic leaving the village
The Comments section also states whether the sign was actively displaying the speed information to oncoming traffic or if it was in ‘Spy Mode’. Spy Mode records traffic information but does not display speeds, and is used to baseline traffic speeds at the start of the period.
PAGE TWO: AVERAGE SPEEDS
The Average Speeds graph includes two averages:
- An ‘average by time period’, which is displayed as a curve on the graph. (one curve per direction: ingoing/outgoing).
- An overall average which is displayed as a numeric value just below the graph.
The ‘average by time period’ corresponds to the arithmetic average calculated on the speeds recorded between the start/end dates. They are presented on a default time period of 30 minutes. The overall average corresponds to the arithmetic average of all the speeds included between the starting/ending dates on the time period selected for the PDF report. The software sums up all of the recorded speeds, then divides the result by the number of vehicles measured.
Note: References in the PDF report to Incoming direction and Outgoing direction relate to the direction of traffic in relation to the SID. ‘Incoming’ relates to traffic heading towards the device. ‘Outgoing’ relates to traffic going past the device in the opposite direction
PAGE THREE: MAXIMUM SPEEDS
Similar to the information for average speeds, the graphs relating to maximum speeds are displayed in curve and number format.
- The maximum speed recorded per time period are displayed in graph form (oncoming and outgoing are reflected in different colours).
- The maximum speed recorded over the entire time period is shown for each direction as a numeric value just below the graph.
PAGE FOUR: VEHICLES PER HOUR
Graphs show traffic volumes for incoming traffic (Green) and outgoing traffic (Blue) for each 24-hour period covered by the report. Total volumes are shown at the top right of the graph
PAGE FIVE: SPEED DISTRIBUTION FOR INCOMING TRAFFIC
PAGE SIX: SPEED DISTRIBUTION FOR OUTGOING TRAFFIC
In these sections, the recorded speeds are represented in pie chart form, and allow you to see the percentage of vehicles which have, or have not, observed the speed limit.
The first segment shows the percentage of vehicles which are travelling below or at the legal speed limit in that location. The second segment shows the percentage of vehicles which are travelling above the legal limit but approximately within the speed tolerances permitted by Wiltshire Police and Community Speed Watch before drivers may be sanctioned. The remaining segments show the percentage of vehicles travelling at excessive speeds.
PAGE SEVEN: PERCENTILES FOR INCOMING TRAFFIC
PAGE EIGHT: PERCENTILES FOR OUTGOING TRAFFIC
The 85th percentile is an indicator that helps illustrate the behaviour of the majority of drivers. It reflects the speed respected by 85% of motorists and is obtained by stripping out the bottom and top & bottom 7.5% of speeds recorded (i.e. strips out the extremely fast and extremely slow vehicles).
If the 85% threshold is close to the average speed recorded, this indicates that the speeds observed on a road are consistent. If it is not close to the average speed, this means that a significant proportion of drivers are above the average recorded speed.
Note: Wiltshire Police use 85th Percentile speeds to determine whether they should conduct their own Speed Checks in any location. This is normally determined by the use of a Traffic Speed Survey which is sometimes referred to as a Metro Count. It involves two rubber strips placed across the road connected to a recording device. To-date, the Parish Council have had to request Speed Traffic Survey reports on a case by case basis, before any Police enforcement action will be considered.
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