Highways Agency - Safe roads, Reliable journeys, Informed travellers

Related pages

• Summary
• 1 introduction
• 2 traffic, congestion and safety issues
• 3 geotechnical issues
• 4 environmental constraints
• 5 option development
• 6 options considered further
• 7 engineering comparison of options
• 8 economic comparison of options
• 9 environmental appraisal of options
• 10 waste management
• 11 public open day
• 12 responses from statutory and non-statutory consultees
• 13 conclusions
• 14 recommendations
• Environmental study findings
• Environmental study findings
• Environmental study findings
• Environmental study findings
• Environmental study findings

A417 Cowley to Brockworth Bypass Improvement

6 OPTIONS CONSIDERED FURTHER

6.1 Three main options have been taken forward for assessment. Two alternatives for the Air Balloon Junction have also been considered. These are discussed below.

Option 1

6.2 Option 1 is shown in schematic preliminary form in Figure 5.1. It should be noted that this is an indicative drawing for information only. Detailed design has not been undertaken at this stage. The scheme comprises the following elements:

• An short bypass of Nettleton Bottom. The existing Cowley Roundabout would be removed and a link road added to serve as local access to the lane to BrimpsfieldVillage. The bypass would traverse through two cuttings in the hills either side of Nettleton Bottom. Each cutting would be up to 7m deep. The southern cutting (about 1,500m long) would pass through the closed Birdlip Quarry to minimise land-take. The road would then pass over a short embankment in fields opposite the Golden Heart Public House before passing through a shorter northern cutting. Landscaping would be provided alongside the embankment to minimise visual and noise impacts.
• The Nettleton bypass would rejoin the Birdlip bypass to the north of the A417 junction with the minor road leading to Stockwell. A bridge over this road would maintain access to Stockwell. The Birdlip bypass would be widened by the asymmetric addition of two lanes on a slight embankment (in the order of 2m high) and largely within the existing highway verge. The carriageways would diverge slightly at Barrow Wake to avoid the geological SSSI.
• The existing junction with the B4070 at Birdlip would be modified to provide left in-left out access only for northbound traffic. Access to the village for southbound traffic would be provided by two new slip roads on the current access to Shab Hill. The current underbridge would be utilised to provide an access to the B4070. A new bridge would also be needed for the two additional lanes on the A417.
• The roundabout at the Air Balloon would be remodelled with the introduction of traffic signals. A new one-way section of road would be created from the current northbound A417 carriageway to the A417 lane travelling down Crickley Hill, effectively bypassing the existing roundabout. A new signalised junction would be introduced at the head of this one-way section to control traffic movements. The southbound approach to the existing roundabout would become one way. Traffic from the A436 wishing to travel westbound on the A417 would therefore need to travel southbound to the signals at the head of the one way system and turn right to go down Crickley Hill (see Figure 5.1).
• Crickley Hill would be widened to provide an additional lane down and a central reservation added with safety barriers. This would mainly be accomplished within the current highway boundary. Retaining structures would be used where necessary to minimise landtake.

Option 2

6.3 Option 2 includes all elements as listed above, differing only at Air Balloon Roundabout and on Crickley Hill, as described below.

6.4 At the Air Balloon roundabout, the current arrangement would be replaced with a new grade separated junction and a new roundabout further up the A436 at the Leckhampton road junction. This is shown in Figure 5.2.

6.5 On Crickley Hill an additional two downhill lanes would be provided on a separated alignment that would run parallel to the existing road but at lower level. The existing three lanes would be retained for eastbound ("up") traffic with one being used as a climbing lane (see Figure 5.2). There would be loss of vegetation on the southern side of the existing road.

Option 3

6.6 Option 3 comprises a twin bore tunnel with two lanes in each bore. Each bore would be D shaped with a maximum diameter of 14m. The bores would have linking tunnels every 100m. The tunnel would be in the order of 2.8km long and be at a gradient of approximately 4.5%. The tunnel would be mechanically ventilated and no ventilation shafts would be required.

6.7 Cowley roundabout would be removed and excavation of a cutting through the hill immediately to the north followed by a short section of road on embankment opposite the Golden Heart Public House would be provided. A control building would be required at this end of the quarry and it is possible that it could be located behind screening in the former Birdlip quarry potentially using the existing gate to the quarry for access.

6.8 The southern tunnel portal would be located in the northern slope of the hillside in the dry valley opposite the Golden Heart.

6.9 A small (500m3) reservoir for fire fighting purposes at the southern portal and possibly a small pump-house would be required. These could be located either in the landscaping within the valley opposite the Golden Heart, or within the Birdlip Quarry.

6.10 The northern portal would be close to the A417 at the bottom of Crickley Hill near Crickleigh Farm. Both portals could be faced with limestone from the excavation of the tunnel. A control building would be required. Two link roads would provide access to Crickley Hill and the A436 from the end of the Brockworth Bypass. Opportunities for landscaping and re-use of material excavated from the tunnel, would be considered to reduce impacts in the AONB.

6.11 This option is shown in Figure 5.3.