A428 Black Cat to Caxton Gibbet improvements

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Ground investigations and surveys

We’re starting a programme of important ground investigations and surveys. These will give us a clear picture of the type of soils, rock types and groundwater where we’ll be building the new road. The work will help us design all the junctions, structures and everything we’re building, as well as plan how to build it safely and in a way that will keep costs down. We’ve produced this ground investigations leaflet to explain more details about the tests we will be carrying out.

The majority of work will take place on private property such as farmland and industrial sites. Any work in public areas will look very similar to normal road works, with barriers around a small section of a pavement or road, with a diversion around it for traffic or pedestrians. We will keep local residents and landowners informed about where we’re working.

 

Frequently asked questions

We’ll be carrying out nearly 400 investigations along the route of the proposed dual carriageway, including almost 100 boreholes, ground water sampling and monitoring, over 200 shallow trial pits and a wide range of unobtrusive geophysical surveys.

More details on each different technique being used can be found here in our ground investigations and surveys guide.

We aim to start our ground investigations in late August and finish in December 2019. We also plan to carry out initial archaeological surveys. These will take up to eight months to complete and are likely to begin in late September 2019.

The majority of our work will be carried out during normal working hours (8am – 6pm), between Monday and Friday. There will be some short-term single-lane closures required around the Black Cat and Caxton Gibbet junctions so we can safely access work sites and move equipment. These lane closures will take place at night (8pm – 6am) to minimise disruption to those travelling. We are not planning to work on weekends. However, should it be necessary, this will be restricted to Saturday (8am – 1pm).

The work will take place at nearly 400 individual locations along the length of the proposed route in Bedfordshire and Cambridgeshire. The vast majority of work will take place on private property with no public access, such as farm land and industrial sites. We have liaised with landowners to ensure we are able to access their land where necessary.

The map below shows the broad area where we will be carrying out our investigations and surveys.

Any work in public areas will look very similar to normal road works, with safety barriers around a small section of a pavement or road, with a diversion around it for traffic or pedestrians.

If work is going to take place next to residential properties, we will write to those properties in advance to let them know what is happening and when.

Some of the techniques we will use will inevitably be noisy and are likely to be heard if you are located within 50 metres of the machine. However, there are many different types of techniques that are non-intrusive and virtually silent, such as the geophysical surveys.

The percussion bore hole rig involves a long, steel pipe that is hammered into hard ground to keep it open, in order to take a sample of the deep soil. The sound of the operation will not be noticeable from more than a few hundred metres away and the works will take place for short durations at each site.

It is not anticipated that the noise will be disruptive during the daytime since the ambient noise levels from the traffic on the road will be significantly higher. Where we think there will be a potential noise impact, such as at night time, we will take necessary measures to mitigate this as much as possible.

Worried about work near your property? Get in touch.

The ground investigation and survey works are not much different from the type of works that we see on our roads and pavements every day – for example, in towns or cities you may see safety barriers around a small section of a pavement or road, with a diversion around it for traffic or pedestrians.

Many of the site locations will not be visible from the road; however in places you may be able to see our vans and rigs working within the fields.

More information, including images of the ground investigation techniques we are using, is available in our Ground Investigations leaflet, pages 8 and 9.

Our contractors will be required to leave every site as they found it. Landowners will be compensated for any damage arising from works, although the timing of investigations and access routes will be negotiated to minimise the effects of the disturbance. Sites will always be left safe and secure.
The information we get from the ground investigation will give our engineers data about the existing ground conditions and any contamination in the ground, which will help us build the new road safely and economically. The information we get from studying the ground conditions will confirm the best methods for constructing the new roads and the most appropriate foundations for bridges and viaducts.
Initially our design relied on records of previous ground investigations and other geological information held by the British Geological Survey and others. This information is extremely valuable but unfortunately it is not typical of the exact route for the proposed scheme, especially in rural areas.
We have 24 kilometres of the route to investigate. The investigations will be split into a number of packages, each relating to a specific length of the route. Each package will typically take a few months to complete, including work on site, laboratory testing and reporting of the results. Investigations on site can take a matter of hours, or days, depending on the location. Additional investigations may have to take place if something unexpected is found and further information is required.
We will be working with specialist contractors to carry out the work in different areas. If you have any questions or concerns, you still have a single point of contact at Highways England who you can contact here.

Our contractors are:

  • AECOM
  • MOLA Headland Infrastructure
  • Skanska
  • Strata Geotechnics
Safety is always our highest priority and nothing will happen until we are certain it can be done safely. We will ensure that the site risks associated with the ground investigations are identified, assessed and managed. We will assess the contractors’ health and safety performance, and security will be managed at all stages, so sites are safe and secure during and outside working hours.
None of the works in our planned locations will affect access to the existing public rights of way. Where investigations or surveys are undertaken in the vicinity of a public right of way, appropriate measures will be taken to ensure the safety of the public and the team carrying out the work.
There will be some short-term single-lane closures around the Black Cat and Caxton Gibbet junctions so we can safely access work sites and move equipment. These lane closures will take place at night (8pm – 6am) to minimise disruption to those travelling.

There is also the requirement for some off-peak traffic management to allow work on side roads across the scheme in the day time. Throughout the works we will avoid any full road closures, traffic restrictions around the junctions, and diversions.

We will mitigate any effect on the local environment by carrying out a pre-work visual survey to ensure there are no ground nesting birds or other ecological constraints. The position of each borehole can be moved slightly to avoid any sensitive areas.

Vehicles are refuelled at the main compound, not on site, and the material used to backfill boreholes is made from a naturally inert material. The works areas are small and unobtrusive and the amount of waste is minimal. The trial pits, for example, are backfilled with the as-dug material.