Network resilience

Network resilience strategy

Document Control

Revision:

Introduction

The local highway network in Plymouth is the council’s most valuable publically owned asset and provides a vital contribution towards the economic, social and environmental well-being of the city. This document highlights the purposes of a resilient network in order to maintain economic activity and access to key services during disruptive events and however this resilient network should be developed.

What is a Resilient Network?

In July 2014, the Department for Transport released the Transport Resilience Review to highlight the need for local authorities to develop and identify a resilient network for their highway network. The purpose of the network is to ensure that “enough is invested, with the right prioritisation and avoiding wasteful and economically unjustified expenditure”.

In the Well Managed Highway Infrastructure Code of Practice also highlights its importance within its recommendations:

Recommendation 20 – Resilient Network:

“Within the highway network hierarchy, a Resilient Network should be identified to which priority is given through maintenance and other measures to maintain economic activity and access to key services during extreme weather.”

Initially all local authorities developed a resilient network to ensure that during the winter season, access to key services and necessary support to the economy are maintained.  It is now important to include other potential events that can impact the network including:

• Extreme Weather including flooding, heatwaves, high wind, snow, extreme cold
• Industrial Incidents
• Pandemic/Infectious Disease

The resilient network will be used as a tactical tool with which priority can be given to minimise the impacts of any event. This can include:

• Additional maintenance inspections to ensure the asset continues to function
• Prioritise funding to mitigate the onset of deterioration
• Prioritise work programmes and modelling to reduce the risk of failure

Currently two resilient networks exist, the Carriageway resilient network, which focusses on the key driven routes for the city and the Footway resilient network which is currently focussed on areas of the greatest concentrations of pedestrians. Through regular review and the standardising of approach it is expected that the footway resilient network in particular will expand in scope to cover the key linking routes between major destinations. Other assets, such as structures, street lighting and traffic signals will generally be aligned to the carriageway resilient network.

Development of the Resilient Networks

Plymouth City Council have developed a resilient network which has been in place for some time and was last formally reviewed in 2019. To identify the resilient network, we have considered the following:

• Emergency Services,
• Maintenance Hierarchies,
• Transportation Hubs,
• Major Employers,
• Major Destinations,
• Major Secondary Schools (those with over 1000 pupils),
• Further Education Facilities,
• Shopping Areas,
• Overall connectivity for the network

The calculation used is the sum of the below decisions, with a score of 1 being the threshold for inclusion in the resilient network. The calculation for the footway network is separate to this, although follows the same principles but at the time of writing, is under review. Note that for each decision, only one option can be selected and each question only applies once and that the decisions made factor in a level of subjectivity from the individual undertaking the analysis:

What this calculation ensures is that a combination of factors is required in order to qualify a street as resilient.

For example, a street with a maintenance Hierarchy of 3b (0.16) which acts as an access route to a major employer (+0.25) would only qualify as being part of the resilient network if it also plays a significant role in network connectivity (+0.8).

0.16 + 0.25 + 0.8 = 1.21

If this site was found not to play a role in network connectivity it would not qualify as resilient. An example of this is Burrington Industrial Estate (see below). The same would be true if it did not act as access to the major employer.

0.16 + 0.25 = 0.41

Consultation

It is important during the formulation of the resilient network that other groups impacted should be consulted. These groups include:

• Neighbouring highway authorities in the South West Highways Alliance
• Emergency services
• Bus Operators
• Internal Stakeholders, including the Street Scene team and Education
• Major businesses such as utilities companies

Monitoring and Review

The current resilient network has been developed using available data held by Plymouth City Council. To ensure the resilience network is kept current and up to date a review will be undertaken every two years, or after any relevant events where lessons have been learnt.

This will involve:

• Review critical service locations and any changes to the network
• Update with any additional data collected that will support the review
• Review neighbouring authorities resilient network

Appendix

Sites Taken into Consideration in 2019 Review

---

Resilient Network

---