The Orwell Bridge in Ipswich, which has been the subject of debate over high wind closures Picture: ARCHANT
A nine-month expert study of the Orwell Bridge's aerodynamics has been launched this month, which will determine the future of wind closure measures from 2019.
In a written update presented to Ipswich Borough Council’s scrutiny committee on Thursday, Highways England’s emergency planning manager James Jackson said an aerodynamic study of the bridge got underway on October 1, by experts at City, University of London.
The study, which will take nine months to carry out, will investigate safe wind speeds for vehicles to cross the bridge, as well as whether high-sided vehicles could be segregated and whether wind barriers can be added.
It will form the basis of all future mitigation measures.
Mr Jackson said: “Once the study is complete, we will be able to ascertain whether traffic segregation is a viable option.
“It will also inform us whether the current closure thresholds can be increased – it would be great if the study reveals that we can let vehicles cross the bridge at higher wind speeds, reducing the frequency of closures due to strong winds.
“However, we require the results of the study before making any changes to the closure thresholds.”
In June, it emerged that Highways England was working on a traffic management plan to segregate cars and lorries on the bridge, in response to questions over whether cars could continue to use the bridge while lorries and other high-sided vehicles were diverted off.
Now, Mr Jackson has said he believes it can be achieved, subject to the study confirming it will be safe to do so.
“We are awaiting the results of the aerodynamics study before implementing any traffic segregation measures,” he said.
“We have already investigated methods of traffic segregation and we believe it can be achieved by investing in more Variable Messaging Signage and by placing traffic officers at junctions 55 and 56 to send high sided vehicles back along the A14 to the approved diversion route and allowing cars to re-enter the slip roads to cross the bridge.
“The aerodynamics study is a very comprehensive piece of work and we need to be absolutely certain that our assumptions are correct before implementing traffic segregation.”
Diversions and congestion
Ipswich MP Sandy Martin has previously urged Highways England to develop multiple diversion routes off the bridge to enable traffic to move better around Ipswich.
While it is understood multiple diversions around Ipswich may not be possible, work is underway to reduce congestion.
Mr Jackson said: “We are currently working closely with Suffolk Highways to develop traffic modelling for the diversion route.
“We believe we can reduce the congestion on the diversion route by calibrating traffic signals to take into account the additional traffic on the diversion route.”
He added that better signs on Highways England’s road network would help inform motorists earlier and reduce the time taken to open and close the bridge.
Sandra Gage, Labour councillor on the scrutiny committee said if warning signs were in place further along the A14, traffic could be diverted well before it even reached Ipswich, and said it was “disappointing we are here a year round and that study is only now starting”.
Maintenance on the bridge is traditionally carried out at night and weekends when the volume of traffic is reduced.
Going forward, this will continue, but while the structure has a 120 year lifespan – taking it beyond the year 2100 – the bearings on the bridge are likely to need replacing in the next decade.
The bearings transfer the weight of the load on the bridge, and impacts on movement of the structure itself during changing weather conditions.
Highways England confirmed that the bearing replacement programme will have a “minimal impact” on the town as lanes will be kept open, and work carried out at night where possible.
Work has ramped up over the last year after a series of closures last winter left Ipswich gridlocked, and business bosses at Ipswich Central estimating a £1million economic hit in lost revenue per day the bridge is closed.
A new protocol is being drawn up, with some measures having already begun to be used.
The length of A14 closure is now reduced to keep the cars on the route for as a long as possible, while a website has been launched to help better inform motorists.
Where possible, closures are warned in advance to help the Port of Felixstowe manage its work with haulage firms and reschedule deliveries and pick-ups.
Ipswich MP Sandy Martin said: “The work that Highways England are doing to try to reduce the impact of closures on the Orwell Bridge is welcome, although it is seriously overdue.
“If they can reduce the number of closures and allow cars to use the bridge when it is closed to high-sided vehicles, then that is a step in the right direction. But we need a much more comprehensive response than that.
“I will be talking to Highways England directly about that – if the current diversion route is the only one available, and the bridge is closed for months for replacing the bearings, then that will not just bring Ipswich to a standstill, it will have a serious effect on the whole British economy.”