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Traffic impact study, november 2004

Traffic Impact Study, November 2004

• Executive Summary

1. Introduction
2. Data Collected
   • Automatic Traffic Counts
3. Summary of Results
   • Automatic traffic counts
   • HGV flows
   • Peak flows
   • Turning Counts
   • Journey Times
4. Conclusion

• ANNEX A & B available as single download (100KB PDF)

Executive Summary

The A6 Alvaston Bypass opened on 17th December 2003 as shown in Figure 0.1 below.

The road is part of the Highway Agency programme to complete the A50 Stoke Derby Link and is the remaining section of the road spur into Derby from the Southern Bypass. The scheme will bypass the area of Alvaston which is currently served by a single carriageway section of the A6. The scheme will link up the A6 dual carriageway in Elvaston to the A5111 Raynesway via a 2.3 km dual carriageway and complete the core trunk road network in Derby.

'Before' and 'After' traffic data was collected immediately prior to and after scheme opening to monitor effects of the new bypass. Traffic data from Derby City Council count sites and existing Highways Agency permanent count sites was obtained to evaluate the effects of the opening of the bypass on strategic routeing patterns in the area.

Figure 0.1 - Daily Traffic Flows 'Before' and 'After' Scheme Opening

The main objectives of the scheme were to:

• Improve journey times;
• Improve the air quality in Alvaston; and
• Reduce the volume of traffic through Alvaston in order to increase safety on the roads particularly for pedestrians.

The main effects of the scheme opening are as follows:

• The A6 Alvaston Bypass was used by about 20,400 vpd in April 2004, and daily traffic flows on the A6 through Alvaston have reduced from 26,000 vpd to 15,400 vpd, a reduction of 10,600 vpd or 41%;
• There are journey time savings of about 11 minutes in the morning and evening peak hours, between the A50 and Derby City Centre, following the opening of the bypass; and
• The roundabout on Raynesway at Alvaston shows a significant reduction of traffic entering the junction, namely 27% over the 12 hour period and 20-30% in the peaks.

1. Introduction

1.1 This report outlines the results of traffic surveys carried out to monitor the effects of the A6 Alvaston Bypass scheme. The A6 Alvaston Bypass is the final link of the A50 Stoke to Derby into Derby. The scheme bridges the missing link of dual carriageway into Derby, as illustrated in Figure 1.1.

1.2 The new A6 Alvaston Bypass was officially opened on the 17th December 2003. Journey time surveys were carried out in November 2003 for the 'Before' surveys and repeated in May 2004 for the 'After' surveys.

1.3 Traffic data from Derby City Council and Highways Agency count sites have been used to evaluate the effects of the opening of the A6 Alvaston Bypass scheme on strategic routing patterns in the local and wider area.

1.4 Chapter 2 of this report discusses the data collected as part of the TIS study. Chapters 3 and 4 summarise the main results and conclusions.

Figure 1.1 - Location of the A6 Alvaston Bypass

2. Data Collected

2.1 The Traffic Impact Study (TIS) for the A6 Alvaston Bypass included the following surveys:

Before Surveys

• 6 Highways Agency permanent automatic traffic count (ATC) sites;
• 13 Derby City Council permanent ATC sites;
• 2 Derby City Council temporary count sites;
• 1 Derby City Council 12 hour turning count survey undertaken in February 2002; and
• Journey Time Surveys (JTS) undertaken on 18th, 24th and 26th November 2003 on three routes.

After Surveys

• For the 'After' surveys the above surveys were redone, plus one additional Highways Agency permanent ATC site on the A6 Alvaston Bypass. An additional JTS route via the new bypass was also included.

2.2 The details of the 'before' and 'after' surveys are described below, and illustrated in Figures 2.1 and 2.2 below.

AUTOMATIC TRAFFIC COUNTS

2.3 The 'before' study comprised surveys at 21 Automatic Traffic Count (ATC) sites including a new site on the A6 Alvaston Bypass, used in the 'after' surveys. The locations of these are illustrated in Figure 2.1.

2.4 The screenlines are defined as:

Screenline 1 - East of Derby

• Dale Road, north-east of Spondon;
• A52 Borrowash bypass, north-west of Borrowash;
• A6005 Derby Road, South-east of Spondon;
• A50 Derby Spur, North-west of Ashton-upon-Trent; and
• A50 Swarkestone, south east of Chellaston.

Screenline 2 - West of Alvaston

• A52 Nottingham Road diversion;
• A6 Derwent Parade, Pride Park;
• A6 London Road, Alvaston;
• A5111 Harvey Road, South-west of Alvaston; and Snelsmore Lane.

Screenline 3 - Narrow Corridor at Litchurch

• A6 London Road (outside Technical Centre); and
• A6 London Road Diversion (Wilmorton Link).

2.5 Various counts around Derby:

• A6 Shardlow Road, Alvaston;
• A514 Swarkestone Road, south of Chellaston;
• C81 Stenson Road;
• A5250 Pastures Hill, Littleover;
• A5111 Manor Road, north of Littleover;
• A5111 Kenilworth Avenue, south of Normanton; and
• A5111 Raynesway.

Figure 2.1 - Locations of ATC Sites

Figure 2.2 - Journey Time Survey Routes

2.6 Journey time surveys were undertaken on four routes, identified as 'red', 'blue', 'pink' and 'green' routes which are illustrated in Figure 2.2 above.

Before

• The 'red' route represents the route from the B5010 to Bradshaw Way (inner ring road) along the A6; and
• The 'blue' route represents the route from the A50 to Bradshaw way (inner ring road) along the A514.

After

2.7 The above two routes were repeated and two additional routes were also undertaken, namely:

• The 'pink' route represents the route from the B5010 to Bradshaw Way (inner ring road) along A6 Alvaston Bypass, A5111 Raynesway and A6 London Road; and
• The 'green' route represents the route from the B5010 to Bradshaw Way (inner ring road) along the A6 Alvaston bypass, A5111 and A52.

2.8 The surveys were undertaken over the morning (0800 - 0900 hours) and evening (1700 - 1800 hours) peak periods, as well as an inter-peak period (1000 - 1400).

3. Summary of Results

AUTOMATIC TRAFFIC COUNTS

3.1 Figure 3.1 below summarises the 'Before' and 'After' ATC information using 24 hour weekday average two-way traffic flows. A summary results table is included in Annex B of this report.

Figure 3.1 - Daily Traffic Flows 'Before' and 'After' Scheme Opening

3.2 The traffic volumes shown in Figure 3.1 are based on seasonally adjusted flows such that traffic volumes from September 2003 have been factored to represent traffic volume levels for April 2004. Thus, any changes in flow are due to the impact of the A6 Alvaston Bypass rather than seasonal differences between September 2003 and April 2004. The seasonality factor from September 2003 to April 2004 is 1.033.

3.3 Figure 3.1 shows the 24 hour two way traffic flow for an average weekday at twenty two locations around the Derby City area. Following the scheme opening 20,400 vehicles per day (vpd) were recorded using the new bypass in April/May 2004.

3.4 On the bypassed section of the A6 traffic volumes have reduced from 26,000 vpd before opening to 15,400 vpd after opening, a decrease of 10,600 vpd or 41%.

3.5 In order to look at change in traffic volumes across corridors, we have grouped individual routes together into screenlines. The main points to note regarding traffic volumes across the screenlines are summarised below.

Screenline 1 - East of Derby

• On the A50 Derby spur, north-west of Ashton-on-Trent traffic volumes increased from 21,100 vpd to 26,300 vpd, representing an increase of 5,200 vpd or 25%. To combat this increase, traffic volumes have reduced elsewhere;
• There is little change at Dale Road, north of Spondon where traffic volumes decreased from 8,400 vpd to 8,330 vpd, a reduction of 70 vpd or 1%;
• On the A52 Borrowash bypass, Borrowash traffic volumes reduced slightly from 53,500 vpd to 52,500 vpd a reduction of 1,000 vpd or 2%;
• Traffic volumes on the A6005 decreased from 11,000 vpd to 9,780 vpd a decrease of 1,220 vpd (11%);
• On A50 Swarkestone, south east of Chellaston where traffic volumes have decreased from 54,700 vpd to 52,900 vpd, an increase of 1,800 vpd or 3%; and
• There has been a switch of some traffic onto the A50 Derby spur, north- west of Ashton-on-Trent to take advantage of the new scheme into Derby. However there are 1,110 vpd, (1%) unaccounted for across the screenline, it is likely that the shortfall is due to an increase on the B5010 at Thurlestone which was not counted.

Screenline 2 - West of Alvaston

• Traffic flows on the A52 Nottingham Road bypass show an increase from 56,800 vpd to 58,400 vpd an increase of 1,600vpd or 3%;
• There is an increase in traffic on the A6 Derwent Parade, Pride Park where traffic volumes increased from 23,100 vpd to 24,000 vpd an increase of 900 vpd or 4%;
• London Road, Alvaston traffic volumes decreased from 19,400 vpd to 13,330 vpd after opening a decrease of 6,070 vpd or 31%;
• Traffic flows on Harvey Road have decreased from 27,600 vpd to 25,100 vpd a decrease of 2,500 vpd or 9%;
• Traffic volumes on Snelsmore Lane increased from 4,410 vpd to 4,880 vpd after opening, an increase of 470 vpd; and
• There is an overall decrease across this screenline of 5,600 vpd or 4%, although the northern section of Raynesway does experience a compensating increase of 7,000 vpd.

Screenline 3 - Narrow Corridor at Litchurch

• On the A6 London Road, Wilmorton Link, traffic volumes decreased from 24,100 vpd to 22,900 vpd a reduction of 1,200 vpd or 5%.
• Traffic volumes on the A6 London Road, at Litchurch, increased from 11,100 vpd to 14,200 vpd, an increase of 3,100 vpd; and
• The traffic volumes show a small switch of traffic from the Wilmorton Link onto the A6 at Litchurch, there are still 1,900 more vehicles across this narrow corridor than in the before situation. This increase is more significant when observing the 6,100 vpd decrease on the A6, north of Alvaston. It is clear therefore that a significant level of traffic has switched onto the A6 for the A514 parallel.

3.6 Other locations showing changes in traffic flows are:

• On the A514 Swarkestone Road, south of Chellaston traffic volumes have fallen from 17,500 vpd to17,100 vpd a decrease of 400 vpd (2%);
• Traffic volumes on Stenson Road have reduced slightly from 13,300 vpd to 12,900 vpd, a reduction of 400vpd;
• On the B663 Chelveston road there is little change as traffic volumes have fallen from 15,600 vpd to 15,300 vpd;
• On Manor Road, there is a decrease in traffic volumes from 33,600 vpd to 32,300 vpd a decrease of 1,300 vpd (4%);
• Kenilworth Avenue, shows a decrease in traffic flows from 26,700 vpd to 25,700 vpd a reduction of 1,000 vpd or 4%; and
• Traffic flows at Raynesway have increased from 42,600 vpd to 49,700 vpd an increase of 7,100 vpd or 17%.

HGV flows

Table 3.1 - Daily HGV flows 'Before' and 'After' scheme opening

	Before			After
	Lights	HGV	%	Lights	HGV	%
A514	15860	683	4.1	16175	739	4.4
A6	18463	2610	12.4	22889	3377	12.9
Total	34323	3293	8.8	39064	4117	9.5

3.8 HGV flows on the A514 at Chellaston show that there is a small change in the proportion of HGV's from 4.1% before opening to 4.4% after opening there is an actual increase of 56 HGV's per day. This change is insignificant.

3.9 On the A50 Derby spur HGV proportions have remained at 12-13%. There is an increase in the number of HGV's from 2,610 HGV's per day to 3,377 HGV'S per day after opening, an increase of 767 HGV's per day. This increase on the A50 Derby spur may be attributed to the A6 Alvaston bypass.

PEAK FLOWS

3.10 In order to see if the scheme has changed the timing of journeys in the area, we have also looked at the peak period changes as well as the daily traffic volume changes.

Table 3.2 below shows the changes in traffic flows at different times of the day observed on A6 Shardlow Road.

Table 3.2 - Traffic Flow changes on the A6 Shardlow Rd

	Before (old A6)	After (old A6)	Difference
0800-0900	1,551	1,091	-460	-30%
0700-1000	5,027	3,042	-1,984	-39%
1700-1800	2,084	1,239	-844	-41%
1600-1900	5,724	3,018	-2,706	-47%
Est. ADT	25,649	15,359	-10,290	-40%

3.11 The main points to note are:

• There is a reduction in daily traffic flows on the A6 Shardlow Road of 10,290 vpd or 40%; and
• Traffic flows decreased by 30% in the AM peak hour suggesting either a small number of vehicles have re-timed back into the peak hour or that this route has attracted vehicles back onto it in the peak hour.

3.12 Table 3.3 below compares 'before' and 'after' traffic flow changes on A6 Alvaston Bypass and A6 Shardlow Road combined, to see how much traffic has been attracted to the corridor.

Table 3.3 - Traffic flow changes on A6 Bypass and A6 Shardlow Road combined

	Before (old A6)	After (old A6)	Difference
0800-0900	1,551	3,177	1,626	105%
0700-1000	5,027	7,998	2,972	59%
1700-1800	2,084	3,404	1,321	63%
1600-1900	5,724	8,501	2,777	49%
Est. ADT	25,649	35,762	10,113	39%

3.13 The main points are:

• Daily traffic volumes have increased by 39% between September 2003 and April 2004;
• In the morning and evening peak periods traffic flows have increased by significantly more than this, i.e. 59% and 49% respectively; and
• In the morning peak and evening peak the increase is highest at 105% and 63% respectively.

3.14 The combined weekday volume of traffic carried by both roads in April 2004 is shown to be 35,762 vpd, increasing from 25,649 vpd in September 2003. The percentage increases in the peak hour are higher, suggesting drivers are retiming their journeys back into the peak hour (i.e. a reduction of peak spreading).

TURNING COUNTS

3.15 Figure 3.2 summarises 'before' and 'after' turning movements using 12 hour traffic flows.

Figure 3.2 - Turning Count Results - 12 hour

3.16 The main points to note are:

• There is a decrease in traffic entering the A5111 Raynesway roundabout from 50,269 vpd to 36,656 vpd, a decrease of 19,613 vpd or 27%;
• There is a 20% reduction of traffic entering the junction from Raynesway (north), made up of a 21% reduction turning left onto the A6 to head south, and a 17% reduction turning right onto the A6 to head towards Derby;
• Traffic entering the junction from A6 (north) from Derby has decreased by 6%. This is a result of a 15% decrease in traffic turning left onto A6 travelling south and an increase of 11% in traffic turning right onto Raynesway; and
• Traffic entering the junction from the A6 south has shows a reduction of 39%, this is made up of a decrease of 56% in traffic turning right onto Raynesway and an insignificant change in traffic straight on onto the A6 London Road.

3.17 Figure 3.3 shows the changes in 'before' and 'after' turning movements in the AM peak (0700-0900).

Figure 3.3 - Turning Count Results - AM Peak

3.18 The main points to note are:

• There is an overall decrease in traffic accessing the Raynesway roundabout in the AM peak where flows decreased from 8,181 vpd to 6,575 vpd a decrease of 20%;
• Traffic entering the junction from Raynesway reduced from 3,502 vpd to 3,220 vpd a decrease of 8% made up of a decrease in traffic turning right on to A6 Shardlow Road and a small increase in traffic turning right onto A6 London Road;
• There is a 25% reduction in traffic accessing the junction from A6 Shardlow Road this is made up of a 29% reduction in traffic turning right onto Raynesway and a 16% decrease in traffic turning right onto A6 London Road; and
• There is a 20% reduction in traffic entering the junction from A6 Shardlow Road, this is made up of a decrease of 36% in traffic turning from the A6 London Road onto A6 Shardlow Road. There is no change in traffic turning right onto Raynesway.

3.19 Figure 3.4 shows the 'before' and 'after' changes of traffic movement in the PM peak (1600-1800).

Figure 3.4 - Turning Count Results - PM Peak

3.20 The main points to note are:

• Overall there is a decrease in traffic accessing the Raynesway Roundabout where traffic has decreased from 8,704 vpd to 6,096 vpd a decrease of 30%;
• There is a 28% reduction in traffic entering the junction from Raynesway, this is made up of a decrease of 28% in traffic turning left to A6 Shardlow Road and a 29% decrease in traffic turning right onto A6 London Road;
• Traffic entering the junction from A6 Shardlow Road decreased by 59%, this is made up of a 74% reduction in traffic turning right onto Raynesway and a 3% decrease in traffic turning left onto A6 London Road; and
• There is a 48% increase in traffic entering the junction from A6 London Road, this is made up of a 74% increase in traffic turning left onto Raynesway and a 33% increase in traffic turning right onto A6 Shardlow Road.

JOURNEY TIMES

3.21 A summary of journey times from the 'Before' and 'After' scheme opening surveys is shown in Table 3.4 below. These journey times relate to the section from A6 Alvaston Bypass/ B5010 to Derby centre at London Rd/Bradshaw Way

Table 3.4 - Comparative 'Before' and 'After' Journey Times on the old A6

Direction	Period	Journey Time into Derby Centre
		A6 (Before)	Old A6 (After)	Time saved After Scheme
Northbound	AM Peak	19:52	11:24	08:28
	Inter-Peak	10:59	09:12	01:48
	PM Peak	16:39	09:29	07:11
Southbound	AM Peak	11:33	09:29	02:04
	Inter-Peak	11:32	08:40	02:53
	PM Peak	19:12	11:22	07:49

3.22 The opening of the bypass has shown a reduction of traffic volumes which has improved journey times along the old A6 through Alvaston where savings of about 8 minutes are observed in the AM peak towards the city centre and 9 minutes in the PM peak out of the city centre.

Table 3.5 - Comparative 'Before' and 'After' Journey Times

Direction	Period	Journey Time into Derby Centre
		A6 (Before)	New A6 Bypass/Raynesway/A52 (After)	Time saved After Scheme
Northbound	AM Peak	19:52	09:19	10:33
	Inter-Peak	10:59	06:59	04:00
	PM Peak	16:39	08:07	08:32
Southbound	AM Peak	11:33	08:05	03:28
	Inter-Peak	11:32	07:20	04:12
	PM Peak	19:12	08:00	11:12

3.23 The table above shows that there are significant time savings observed by using the new A6 Alvaston Bypass, A5111 and A52 into Derby centre. Journey time survey results show that there is a saving of about 11 minutes in the PM peak out of the city centre and in the AM peak travelling towards the city centre when using the new bypass.

Table 3.6 - Comparative 'Before' and 'After' Journey Times

Direction	Period	Journey Time into Derby Centre
		A6 (Before)	New A6 Bypass/London Road (After)	Time saved After Scheme
Northbound	AM Peak	19:52	10:31	09:21
	Inter-Peak	10:59	07:58	03:02
	PM Peak	16:39	09:31	07:08
Southbound	AM Peak	11:33	08:59	02:33
	Inter-Peak	11:32	08:13	03:20
	PM Peak	19:12	10:12	09:00

3.24 It is clear from the table above that time savings are being observed by using the A6 Alvaston bypass then onto Raynesway/London Road into Derby City centre. Time savings of over 9 minutes are being observed in the AM peak in the northbound direction.

3.25 A summary of journey speeds from the 'Before' and 'After' scheme opening surveys is shown in Table 3.7 below.

Table 3.7 - Comparative 'Before' and 'After' Journey Speeds

Direction	Period	Journey Speeds (mph)
		Old A6 (Before)	Old A6 Bypass (After)	New A6 Bypass (After)	Speed Difference
Northbound	AM Peak	14	22	54	40
	Inter-Peak	21	24	59	39
	PM Peak	15	25	56	40
Southbound	AM Peak	22	25	56	34
	Inter-Peak	22	27	58	36
	PM Peak	14	21	52	38

3.26 The speeds on the bypass are up to 40 mph faster than the old A6.

3.27 In both the northbound and southbound directions the 'after' speeds are more consistent, indicating an improvement in journey time reliability.

4. Conclusion

4.1 The traffic data collected as part of this Traffic Impact Study has shown that the A6 Alvaston Bypass, which opened on the 17th December 2003 has been successful in routeing some traffic away from the A6 through Alvaston. The main conclusions are:

• The new A6 Alvaston bypass was used by about 20,400 vpd in April 2004;
• Daily traffic volumes on the bypassed section of the A6 through Alvaston have reduced from 26,000 vpd to 15,400 vpd, a reduction of 41%;
• Given the alternative options for routing into the city, there have been a number of significant traffic re-routing on the south side of the city;
• Journey time savings of up to 11 minutes in the PM peak out of the city centre and in the AM peak travelling towards the city centre by using the A6 Alvaston bypass, Raynesway and A52 route; and
• The removal of traffic on the old A6 at Alvaston has led to improved journey times of 8 minutes using the old A6 after opening of the Bypass, but when the bypass is used, then time savings into Derby increase to over 9 minutes. This means that it is quicker to use the bypass/Raynesway/London Road route when travelling into Derby than just staying on the A6 through Alvaston.

4.2 The One Year 'After' count for this scheme's Post Opening Project Evaluation (POPE) will be undertaken in April 2005.