Use of Zoneguard A14 Kettering Bypass J9-J7
A14 Scheme Overview
The J9-7 section of A14 runs around the south-west edge of Kettering. It forms part of the Trans-European Network linking the West Midlands, M6, M1, and A1 with the container port of Felixstowe and, consequently, carries a high proportion of HGVs. This section of A14 also acts as a bypass for the town. This is one of the A14’s most congested sections and carries some 70,000 vehicles per day. It has closely spaced junctions with other major road corridors (A43, A509, A6) some of which share parts of the A14. Much of the congestion around Kettering is caused by local traffic ‘junction hopping’ on and off the A14.
1. The Objective
The existing dual carriageway on the A14 Kettering is 9.3 metres wide. The project required a contraflow to fit on westbound carriageway comprising of HGV Lane 1(3.1m) and light vehicle lane 2 (2.5m) for Westbound traffic and light vehicles lane 2 (2.5m) for Eastbound traffic see figure 1. Under current standards (TD1906 & Ch8) the buffer between opposing traffic would need to be 1.2m.
Zoneguard is a new product and has not been used on HA network previously to A14. The proposed reduced buffer requirement can save costs and time. It can also improve safety as case study will demonstrate.
A14 Works Area
- Zoneguard System 1 (currently listed as Zoneguard has a containment class of N2 with a working width of W6 and ISL – B. Tested length 96m, anchored at the ends.
A14 Buffer Zone
- Zoneguard System 2 has a containment class of N2 with a working width of W2 and ISL - B. Tested length 96m anchored at 12m intervals.
No other temporary steel vehicle restraint has this working width. Zoneguard tested deflection when bolted every 12metres is 100mm.
TD19/06 paragraph 8.22 (ii) the buffer zone between opposing traffic flows must not be less than 1.2 m wide;
Survey (TOPO) information gathered prior to construction on A14 had established that the carriageway width varied between 9.0m and 9.3m.What this meant is proposed phase 3 contraflow strategy (figure 1) as tender documents “preferred Option” would not laterally fit existing paved area as carriageway would require a constant 9.3m. This reduced width <9.3m was over significant lengths of A14 westbound carriageway. The bmJV team identified this issue early in contract and looked for cost effective options / opportunities to avoid widening full length along A14 westbound.
Following approval of historic departure granted by Highways Agency Road Restraint Team on 12th December 2013.The use of Zoneguard (900mm buffer see figure 2) enabled contraflow to fit the existing A14 westbound carriageway laterally. Also for much of length the single contraflow lane width was increased to 2.65m (improvement from the minimum of 2.5m).
As a consequence this allows 900mm buffer in contraflow instead of 1200mm which is stated as must in TD1906.
Only a stretch of 500 metres required widening in verge due to closer proximity of existing VRS in central reservation. This was because existing 1 metre hard strip was used as contraflow lane (see insert photo for removal of hardstrip) and this left no setback for existing central VRS to contraflow traffic.
Durability is not really affected; reduced maintenance and improved safety as roadworker has no requirement to clean Zoneguard.
6. Benefits to A14
- Reduced widening over 4.3 kilometres = cost benefits identified of £247,866.00
- Programme maintained widening could have increased by 2 weeks
- No increase to programme maintaining improving JTR for roaduser and reduced risk to roadworker
- Greater access for winter and recovery operations with increased >2.5 contraflow lane
- Meeting (5th Dec 2013) with emergency services in discussion the meeting seen the benefits additional width will allow HGV emergency vehicles and Recovery vehicles safer access during incident or break downs.
Zoneguard System 2 (A14 Buffer) and Zoneguard System 1 (A14 Works area protection) has now been installed for 9 weeks on A14 (11th March 2014) with no negative impact with product or the reduced 900mm buffer to road user or worker .
7. Other safety considerations - HAVS
Asset International on the A14 trialled Orteco piling rig (see image 1), with a new attachment to punch the carriageway. A pilot hole was drilled to a depth of 50mm, and then the piling rig drove a hardened spike into the ground. In principle the process was a success, but asset found that after 20 holes were complete, the spike attachment became very hot, and started to become blunt. After 28 holes the attachment was completely blunt, and could not be used.
Further to this a new drill (see image 2) that can be used totally HAVS free has been sourced. The unique item of equipment is essentially a rock drill, mounted on a stand, with a hydraulic ram. Asset imported this drill on a trial basis, and conducted trials in mid February 2014. The equipment performed extremely well, and further trails have been a success. The drills will be used on another Morgan Sindall project A1 Leeming to Barton to install buffer zone with Zoneguard system 2 for contraflow in early April 2014.