It pays to have schemes ready in case the government wants a quick start project. Portsmouth had a motorway junction in hand from the 1970s. Jackie Whitelaw reports on construction progress.
It is not often that people have praise for the foresight of their 1970s predecessors. But in the case of the M275 into Portsmouth, a decision made over 30 years ago to design and build the motorway at Tipner on the outskirts of the city with the expectation that an interchange would eventually be built below is finally paying off.
At Tipner, the motorway is built on embankment and includes a seemingly redundant bridge over what appeared, until this year, to be an imaginary roundabout.
But work now underway to construct a new junction means that the roundabout is becoming reality and the 1970s structures are being put to work.
New on and off slip roads are being created to connect to an interchange circulating beneath the motorway and under the bridges. The new investment will open up opportunity to regenerate a derelict part of the city along with improved public transport links in the form of a bus lane and park and ride site.
Tipner, once home to waterfront scrapyards and contaminated land will become a smart gateway to the port, with new homes and businesses.
“Portsmouth is unique in having motorway right into the city centre,” says Portsmouth City Council head of transport and environment Simon Moon.
“At the moment the approach is a bit of an eyesore and not representative of the place.
“We have a beautiful harbour, people come here to set off on holiday to the Isle of Wight and further afield and there is all the wonderful history in the Dockyard with HMS Victory and the Mary Rose.”
The city is also unique in that the 1.7km of motorway Moon is referring to is owned by the council not the Highways Agency, although the route is part of the strategic network and maintained to the same standards.
“Going back to the 1970s when the motorway was built there was always aspiration for a junction at Tipner,” says Moon. “The preparatory work was done. Earthworks and bridges were put in place and profile for a roundabout was created beneath. The junction was always seen as ours to develop, and in the last six years there has been a concerted effort to deliver it.”
“The junction was always seen as ours to develop, and in the last six years there has been a concerted effort to deliver it”
Simon Moon, Portsmouth City Council
The plans are for the motorway junction, a 663 space park and ride, a bus lane to the city and development of the area to the east of the motorway.
Eventually it is hoped there will be development on both sides of the motorway with a bridge to Horsea Island to the west linking in with a future bus rapid transit system.
One of the benefits of having a scheme that has been refined over three decades is that when the government came calling for quick start projects back in 2011 Tipner was ready to go.
“We were shortlisted in the first sift of 20 projects in January 2012 along with another scheme of ours, the Northern Road bridge, and having two jobs on the list was a bit of coup for us,” Moon remembers.
“We then spent time refining the bids and looking at opportunities to procure the schemes. In September 2012 we got the nod for Northern Road and approval for Tipner followed in December.”
For Tipner, the council received Department for Transport grant of £19.5M and the city is contributing £8.5M towards the £28M total cost.
The cost benefit ratio is 3.23:1. The city and its 210,000 residents are crammed in around the water, making Portsmouth the most densely populated area of the country outside central London.
Population growth predictions mean new homes must be provided and land and access for new business created. Tipner has the space but the local road network could not cope with extra traffic from any development and suffers from poor public transport provision.
A new motorway junction and associated bus lane was the answer and the government agreed, seeing the investment as a way to unlock economic growth.
Winner of the NEC target cost design and build contract was the Volker Fitzpatrick Colas (VFC) joint venture. Working with its designer Halcrow it refined and developed outline proposals drawn up by Atkins.
The joint venture is constructing the new roundabout beneath the motorway with associated 350m long slip roads and a 1.2km new bus lane adjacent to the southern carriageway, linking the project into the existing network. Works also include installation of a new full span gantry to the north and the upgrade of an existing gantry to the south.
Phase two of the job involves building the park and ride centre and passenger building.
“The job is target price but we have an unforeseen ground conditions arrangement because the area was so heavily contaminated,” says VFC’s deputy project manager Shine Salur. “There is all sorts here including creosote and asbestos. We also have an issue with Japanese Knotweed.”
The Health & Safety Executive has been notified about the asbestos and specialist subcontractor Envirochem is being called in to deal with it. Much of the contamination and the knot-weed will be buried under deep fill on top of a Terram geotextile layer using spoil excavated for the slip roads. “Earthworks are also being reused to raise the level of the interchange by 1.2m to protect against flooding,” Salur says.
Colas associate director Graham Martin was bid director for the Tipner contract. Innovation and good understanding of the client and the local area helped the joint venture win the deal, he says. Colas is behind the Ensign PFI which manages all Portsmouth’s roads and that experience gave the team insight into priorities for residents and local councillors.
In terms of value engineering, a way to fit the bus lane into the existing trace of the motorway, much of which is on embankment, was a major advantage to the VFC bid.
“There is high voltage cable running alongside the motorway and we did not want to divert it,” Martin says.
“Our suggested solution was to replace the traditional central reservation with a concrete barrier which needs less set back. This gained us the extra 1m that is allowing us to expand the carriageway to the south and fit the bus lane onto the hard shoulder.”
Work began in January, and in May drivers into the city were being diverted through a major contrafl ow to allow work to start on the south side of the motorway.
Slip roads on the northern side opened in the same month and are taking construction traffic off local streets as it can arrive by motorway.
The job is due for completion in spring 2014.