A19, South Tyneside

A19

Aerial photograph showing a major road junction construction with a flyover, earthworks and heavy machinery
Aerial photograph showing a major road junction construction with a flyover, earthworks and heavy machinery

Client: Highways England
Main contractor: Costain
Structural engineer: Jacobs
Value: £181m (estimated)
The Testo's and Downhill Lane junctions are about 1.1km apart on the A19 near Sunderland. They both suffered from long queues and congestion, particularly at peak times. The Highways England's improvement programme wanted to address this by constructing new flyover structures and reconfiguring the junctions while maintaining traffic flow.

We provided temporary works and construction engineering from the early design stages, working closely with Costain to develop construction methodologies, geotechnical solutions, and structural approvals that ensured safe, efficient delivery of this complex highway infrastructure project.
24/7
temporary bridge trestle and construction methodology designed keeping the road in operation
2
junction schemes, Testo's Roundabout and Downhill Lane delivered as a coordinated improvement programme
2
Costain Blue Badge awards in recognition of our high-quality project delivery

our role

our role
Wentworth provided comprehensive temporary works and construction engineering services across both junction improvement schemes.


Our scope included:


  • geotechnical design for slope stability, retaining structures and CAT 2 checks of proprietary equipment schemes
  • foundation design for temporary bridge trestle and water diversion systems
  • CAT 3 checks of the flyover superstructure construction methodology
  • reinforcement sequencing for permanent structures
  • using Road Restraint Risk Assessment Process (RRRAP) for vehicle restraint risk assessments
  • securing Approval in Principle for the A19 flyover and South Bridge.

Capabilities

Capabilities

  • Bridges & Highways
  • Geotechnics
  • Structural Engineering
  • Construction Method Engineering
  • Temporary Works

Designing temporary bridge to maintain traffic flow

Designing temporary bridge to maintain traffic flow
Aerial view of the A19 Testo junction showing a large crane lifting a pre-cast concrete bridge seciton into place over a dual carriageway construction site
Aerial view of the A19 Testo junction showing a large crane lifting a pre-cast concrete bridge seciton into place over a dual carriageway construction site
Constructing the flyover required temporary access for plant and materials across live carriageways without disrupting the 24/7 traffic flow on this key route.

We conducted CAT 3 checks and designed foundations for the temporary bridge trestle, analysing ground conditions and load requirements to ensure stable support throughout the construction programme. Our construction sequence integrated temporary works with the permanent structure installation, minimising traffic management impacts.

This approach enabled Costain to construct the flyover elements efficiently while maintaining highway operations and providing certainty for this time-critical infrastructure project.

Managing geotechnical stability

Managing geotechnical stability
The variety of ground conditions meant our engineers designed multiple retention solutions, including sheet piling, slope stability measures, and retaining walls across junction areas. Excavations near live carriageways required robust temporary works design to prevent ground movement affecting highway safety.

Wentworth carried out detailed geotechnical analysis and developed retaining wall methodologies tailored to each location. Our team ensured safety with CAT 2 checks on proprietary trench boxes and sheet piling frames, and designed a ‘clay stank’ using sandbag walls to control water flow during construction.

Together, these measures maintained safety and minimised traffic disruption throughout the project.
The underside of an overpass bridge structure with reddish-brown weathering steel grinders and a concrete abutment.
The underside of an overpass bridge structure with reddish-brown weathering steel grinders and a concrete abutment.

Protecting people during construction

Protecting people during construction
As construction was carried out adjacent to live high-speed carriageways, we had to ensure robust protection was incorporated into our design methodology for both highway users and workers. Risk assessments were critical to preventing accidents and protecting edges and services, while Vehicle Restraint Systems (VRS) were needed to stop vehicles from entering construction areas.

Wentworth developed a comprehensive Road Restraint Risk Assessment Process (RRRAP) for the VRS, analysing vehicle impact scenarios and designing appropriate barriers. We maintained a live design risk assessment document, regularly updated to reflect site changes for the client.

This approach guaranteed system resilience to vehicle impacts, preventing accidents and protecting all stakeholders.

Outcomes

Outcomes
This project demonstrates the value of early construction engineering involvement in complex highway infrastructure projects, where temporary works design directly impacts programme delivery and safety on operational routes.


Key results:


  • Recognised quality delivery: Awarded two Costain Blue badges for continued high-quality delivery throughout the project
  • Programme certainty: Phased temporary works design enabled continuous construction without unexpected delays
  • Contractor confidence and risk reduction: Independent CAT 3 checks and geotechnical design gave Costain certainty in its construction methodologies before starting on site
  • Health and Safety prioritised: Live design risk assessment enabled proactive identification and mitigation of construction hazards
  • Collaborative delivery: Weekly meetings and regular updates with Costain ensured transparent progress tracking of key deliverables and changes.