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Woodmill Bridge Signalisation FAQs

Has this work been consulted on?

Yes, a public consultation exercise was carried out regarding the provision of traffic signals at Woodmill Bridge at the end of 2018. Overall, the majority of submissions indicated a preference for the installation of traffic signals to manage queues at Woodmill Bridge.

Why will the signals be part time?

We conducted traffic modelling and signal trials on site. The analysis and observations shown from these is that the signals are effective when there are queues (peak times) but not when there are no queues (off-peak times). The signals would increase journey times when there is less traffic, which is why we decided to go with part time signals.

In order to minimise any confusion, signage will be in place to communicate that they are part time signals.

We will also be monitoring the junction to make any changes as necessary.

 

Why aren’t we doing the work overnight if it will cause disruption?

We looked at various options for carrying out the work. We understand and apologise for the inconvenience of closing the bridge for two weeks. However this will minimise the impact to road users and enable us to complete the work in the shortest time frame.

Why aren’t we doing the work during school holidays?

We carefully manage and coordinate all road schemes across the city. The work at Woodmill Bridge has been programmed to run in January to avoid conflicts with other major projects planned throughout the year and to manage pressures on the network. We will be working additional hours and weekends in order to minimise the impact to road users and complete the work in an efficient and timely manner.

Will the lights automatically switch on during certain times (e.g. 6am to 10am) regardless of queues?

Yes, the lights will come on automatically at 7am to 10am and then 3pm to 6pm. We will monitor the lights and change this if necessary.

What kind of green time will be given to each arm of the junction?

Based on the turning counts and the observations we had on site, the bridge is very tidal. Therefore, the AM peak heading West and the PM peak heading East will have a larger maximum green time.

Initially, the junction will be configured with values we created during the modelling and observed during the trial. We will carry out some validation over the first week or so and adjust the times accordingly. We will also use the detection on site to flush out any excessive queuing that occurs.

Example of signal timings on the PM eastbound peak flow.

Will the lights rest on red in the absence of demand?

Yes, in order to discourage anyone speeding towards it.

When an ‘all red’ phase of lights goes on to ensure the junction is cleared, what will the rough time for the clearance be?

During our trial of the system this was set at 20 seconds. However, this was carried out with temporary lights, so with the proper lights it can be reduced slightly and then extended up to a higher value with the detection we will be installing.

What is the minimum time that the lights will run for?

They have been configured to stay on for 5 minutes once all the queues are cleared, however we will be monitoring the lights and so this can be changed if necessary.

When the lights are switched off, will the bridge go back to the priority rule?

Yes, this is the case.

Will the signals detect an excessive queue and what is defined as an excessive queue?

There are detectors on the approaches to the bridge which will detect if vehicles are stationary for more than a configurable time - initially 20 seconds – which will trigger the lights to come on. There is one at the junction of Langhorn Road and one near the Manor Farm Road junction mini roundabouts.

Will this be dangerous for pedestrians as cars will speed through when they get green time? Have/will you review safety?

We have taken pedestrian safety into consideration and, as well as new traffic signals to manage queues, the scheme also includes a new puffin pedestrian crossing where the Riverside Park walk crosses Woodmill Lane. As always, we will continue to closely monitor the situation and will take necessary action to address any issues should they arise after the scheme has gone live.

How do I ask questions or find out more?

For up-to-the-minute travel information, follow us on Twitter @scchighways.

For further information, please contact roadworks@southampton.gov.uk.