Highways Agency - Safe roads, Reliable journeys, Informed travellers

Figure 3.1 below summarises the 'Before' and 'After' ATC information using 5-Day Average two-way traffic flows. A summary results table is included in Annex A of this report.

Figure 3.1 - 'Before' & 'After' Traffic flow Results: 5 Day Average

Following scheme opening on 3rd October 2003, around 18,100 vehicles per day (vpd) were recorded using the new bypass. Traffic volumes on the old section through the village fell from 26,400 vpd before opening, to 9,200 vpd post opening, showing a 65% reduction in traffic. The scheme has therefore been successful in routeing traffic away from the village. The other main effects are:

• Traffic flows at the revised Tring Hill roundabout has increased from 21,900 vpd to 23,800 vpd, an increase of nearly 9%;
• On the B488, just east of the bypass, daily traffic volumes have risen from 8,120 vpd to 8,590, an increase of 470 vpd, or nearly 6%;
• On the A413 Walton St Gyratory, Aylesbury, there has been an increase of 1,700 vpd, from 32,300 to 34,000, but further south on the A413 at Stoke Mandeville, there is a decrease of 700 vehicles, suggesting an initial routing change following the opening of the bypass from the B4009 / B4544 and A413, to the new A41 bypass route, to access or egress Aylesbury from the south;
• On the B4544 at Weston Turville, traffic volumes have reduced from 8,800 vpd to 7,900 vpd, a decrease of 11%, and on the parallel B4009, traffic volumes have fallen from 13,100 to 12,300 vpd, a decrease of 6%;
• On the B4009 north of Wendover, the decrease is shown to be 500 vehicles or 4% and there are smaller decreases of 60 vehicles on the B4009, west of Wendover and on World's End Lane; and
• On the A41 at Bedgrove and on the A41 Berkhamstead Bypass there is an equal increase of 1,300 vpd.

 

JOURNEY TIME SURVEYS

A summary of the Journey Times from the 'Before' and 'After' scheme opening surveys for all of the suggested routes is shown in Annex B, and is summarised for the A41 in Table 3.1 below. The final column shows the time savings between the old road in the 'Before', and the bypass in the 'After' scenario, and therefore represents the expected time saving for through traffic. Table 3.2 shows the comparable table but for Journey Speeds.

Table 3.1 - Comparative 'Before' & 'After' Journey Times around Aston Clinton

Direction	Period	Route Used			Time Saving (using bypass)
		Old A41 (before)	Old A41 (after)	A41 bypass (after)
Eastbound	AM	12:24	09:37	06:51	05:33
	INTER	10:09	10:03	06:57	03:12
	PM	09:54	09:21	06:55	03:00
Westbound	AM	11:58	11:37	06:51	05:07
	INTER	10:04	09:42	07:00	03:04
	PM	15:42	09:09	07:00	08:42

Table 3.2 - Comparative 'Before' & 'After' Journey Speeds

Direction	Period	Route Used			Speed difference (KPH)
		Old A41 (before)	Old A41 (after)	A41 bypass (after)
Eastbound	AM	44	58	91	46
	INTER	54	55	89	35
	PM	56	59	90	34
Westbound	AM	46	47	91	45
	INTER	55	57	89	34
	PM	35	60	89	54

Table 3.1 above shows significant time savings due to the new A41 Aston Clinton bypass. In the AM peak over five minutes can be saved by using the bypass in both directions; and westbound towards Aylesbury in the evening peak, Journey Time savings of nearly 9 minutes are shown. In the Inter-Peak period, time savings of 3 minutes are shown for each direction of travel.

Annex B shows the complete set of results for all journey time runs and shows that:

• Journey times reduce on the A41 through Aston Clinton after the scheme has opened reflecting the large reduction of traffic and congestion through the village, with times reducing from 30 seconds to up to 6 minutes;
• On the A413 (red route), the small reduction of traffic has resulted in insignificant time savings of only a few seconds;
• On the B4544 (black route) and B4009 (blue route) the reduction of 1,000 vpd has led to small time savings of up to 1 minute;
• In terms of Journey Speeds, traffic speeds on the A41 through Aston Clinton have increased from 35-55 kph to 90 kph on the new bypass;
• In addition, Table 3.2 shows the speeds varied on the old A41 to Aston Clinton from 35-56 kph depending on the time of the day, but all the time periods after opening show Journey Speeds of 90 kph indicating that journey reliability has been significantly improved, and
• Journey Speeds on the A413, B4544 and B4009 show very small increases.