Document Control
| Version | Date | Author | Change Description |
| 1.0 | 27/08/20 | Initial Draft | |
| 2.0 | 07/03/2022 | Reviewed and Updated | |
| 3.0 |
Introduction
Asset management is widely accepted as a means to deliver a more efficient and effective approach to the management of highway infrastructure assets through longer term planning and ensuring that levels of service are defined and achievable for available budgets. This approach supports making the case for funding and better communication with stakeholders facilitating a greater understanding of the contribution highway infrastructure assets make to economic growth and the needs of local communities.
This document outlines the lifecycle plan for the Traffic Signals asset for Plymouth City Council outlining the approach to management and maintenance of the traffic signal assets.
Scope
This document covers all traffic signal control equipment on the Plymouth highway network that Plymouth have a responsibility to maintain. This includes all traffic signal junction and all controlled pedestrian crossings incorporating Pelicans, Puffin and Toucan crossings.
Causes of Asset Deterioration
The main causes of traffic signal deterioration are itemised below:
Table 1: Deterioration and Associated Defects
| Cause of Deterioration | Description | Typical Defects |
|---|---|---|
| Weathering | Damage from wind action, water ingress and freezing | Deterioration of plastics, rubber seals, coatings to poles. Corrosion of metals |
| Degree of exposure of the site | Sites in exposed locations are at higher risk of severe weather conditions eg greater wind loading | Deterioration of plastics, rubber seals, coating to poles. Corrosion of metals |
| Vegetation, overhanging trees | Dirt and dust adhere to assets due to leaf sap and other residues | Illegible and obscured signals |
| Rutting in carriageway | Plastic deformation of bituminous construction layers | Damage to loops |
| Vandalism/Graffiti | Spray painted words, smashed lenses, damaged push button units | Illuminated surfaces damaged |
| Ageing | Assets approaching end of design life, affected by sunlight | Fragile coping |
| Salting | Assets can be damaged by excess salt spray | Rust damage |
| Road Traffic Accidents | Assets damaged by collisions | Pole and head damage. |
National/Local Guidance and related documents
The maintenance of electronic traffic signal equipment is governed by a series of national documents and guidance including:
- Well Maintained Highways A Code of Practice 2016
- Management of Electronic Traffic Equipment A Code of Practice (22 September 2011)
- DMRB – Volume 8 Traffic Signs and Lighting Section 1 Traffic Signals and Control Equipment Part 2 TD 24/97
- MCH 1540 Loop Detectors Standards for Highways
- Traffic Management Act
This document is a live document that will be reviewed annually or whenever a significant change is required to any of the process or procedures documented within it.
Asset Data Management
Inventory Data and capture
Accurate and up to date inventory of the asset is an important element to good asset management. Traffic signal data held on Imtrac is usually reliable and up to date. The traffic signals team will add details of the equipment on any new traffic signal infrastructure to the Imtrac database following commissioning. This information is also used to calculate energy use when it is passed to the energy supplier. At present Plymouths traffic signal stock consists of:
| Description | Type |
|---|---|
| Traffic signal Junction | 119 |
| Signal controlled pedestrian crossings | 62 |
Inspections and Surveys
Traffic signal junctions are inspected yearly by our traffic signal maintenance contractor as part of the Periodic Inspection programme to ensure they remain safe for public use. Inspections are conducted by a number of methods:
- Visually by the inspector with evidence gathered using photographs
- Electrical Testing
Further inspections are carried out by Plymouth City Council by a number of methods:
- Visually by the inspector with evidence gathered using photographs
- Signal timing inspections during the AM and PM peaks
Any faults found during these inspection will be recorded and uploaded onto the Imtrac fault management system so that they can be dealt with. The inspection also provides the data required to support good asset management practice.
Asset Condition and Assessment
Condition
Plymouth City Council monitor and record the condition of the asset through:
- The inspections as part of the maintenance and inspection element of the traffic signal maintenance contract
- Equipment Age
- Equipment functionallity (Fitness for purpose)
- Compliance with latest standards
Assessment
In general, the condition assessment is an amalgamation of the above reports and observations by the Authority, the equipment supplier and information collected by the maintenance contractor. Priority in terms of treatment is identified using a condition score with associated objective commentary. This results in a recommendation of priority for treatment.
Lifecycle Planning
There is an increasing realisation that traffic signal installations have become a key element in implementing schemes which will meet Local Transport Plan targets. Thus the equipment population is increasing all the time. It is therefore essential to ensure that a robust Lifecycle Management Plan is developed for traffic signal infrastructure so that revenue investment is allocated to meet the needs identified in the plan. Traffic signal infrastructure has a 15-20 year design life.
A simple model has been applied for lifecycle planning and is held by the signal team in their asset management folder. Each installation is point scored against a number of factors as below:
- Age of cabling
- Age of controller
- If the istallation is on the Resiliant Network
- If the installation is on the Major Road Network
- If the site is part of an Air Quality Management Area
- If spars for the site are obsolete
- Visual Inspection
- If the site utilises LED technology
- If the site has Extra Low Voltage equipment
- Consequence of Failure
Asset Condition
Traffic signals have a 15-20 year design life and while equipment on that site can change during this lifecycle due to issues that may incur rust damage/accident damage/equipment failure etc. At present 34, or 19%, of the traffic signal sites are beyond their design life with this rising to 82, or 45%, in the next 5 years.
| Asset | 0-5 Years Old | 6-10 Years Old | 11-15 Years Old | 16-20 Years Old | 20+ Years Old |
|---|---|---|---|---|---|
| Traffic Signal Controller | 50 | 24 | 25 | 48 | 34 |
Performance Management
KPIs (Key performance Indicators) are included within the maintenance contract principally for the purpose of monitoring contract performance. But these are also used to monitor to performance of the asset.
- KPI 1- Priority 1 fault attendance, 2 hour.
- KPI 2- Priority 1 fault fixes.
- KPI 3- Priority 2 fault fixes, 24 hour.
- KPI 4- Priority 5 fixes.
- KPI 5- Periodic Inspections.
- KPI 6- Bulk Lamp Changes.
- KPI 7- Premature Lamp Failure.
- KPI 8- Spares Availability.
- KPI 9- Loop Repairs
- KPI 10- Traffic Signal Availability.
In addition to the contractual KPIs, the Performance Management framework addresses the below traffic signal related measures, which have been aligned to the asset management objectives identified in the Asset Management Strategy:
| Performance monitor | Definition | 2021/22 Target | 2021/22 Result | Reporting Frequency |
|---|---|---|---|---|
| SE-TS-001 | % of traffic signals sites that needs replacing | <34% | 19% | Annually |
| SE-TS-002 | % of urgent Traffic Signal faults fixed on time | <87.7% | 91.7% | Quarterly |
| SE-TS-003 | % of traffic signals stock with faults (urgent and non-urgent) | <96% | 84% | Quarterly |
| SE-TS-004 | % of ITS inspections carried out on time in the last year | >79% | 54% | Annually |
Reactive Maintenance and Defect Repairs
Reactive maintenance is carried out by the specialist equipment maintenance contractor as required.
Faults are reported from a variety of sources:
- Remote monitoring through the PCSCOOT system
- Faults identified by MOP / stakeholders and recorded through Firmstep.
- Faults identified through Periodic Inspection recorded through Imtrac
- Faults identified by the maintenance contractor recorded through Imtrac
- Faults identified by Plymouth City Council staff
Once a fault has been identified a priority level is applied by the PCC staff and a job is raised on the Imtrac system as below:
| Priority | Examples (not an exhaustive list) | Response Time |
|---|---|---|
| Priority 1 – Urgent Fault | Signals stuck, omitting a phase or all signals out; issues causing significant disruption or conflicting information; damaged or dangerous equipment;failure of red lamp/LED; multiple green lamp/LED failures in the same phase | 2 Working Hours |
| Priority 2 – Non-Urgent Faults | Faults with detection systems;Any defects with lamps/LEDsIssues with rotating tactile cones or pedestrian “bleeper” unitsDefects with unit doors or hinges; | 13 Working Hours |
| Priority 3 – Remedial works | Where a full repair was not possible on the first visit and the fault was made safeWhere works required are complex and unable to be completed in the alloted timescale | 26 Working Hours |
| Priority 4 – Routine faults. | Faults that are not critical to the safety of the highway such as;Single green lamp or LED failures;Defects with back boards or hoods;Defects with vehicle count detection systems | 5 Working Days |
| Priority 5- Demoted faults and Chargeable Works. | Where a higher level fault has been identified but a full repair was not possible due to situations such as severe weather or an inability to access.Where more significant engineering works such as excavation of the highway are needed | 21 Working Days |
Maintenance Strategy and Investment
Currently, a number of maintenance strategies are being considered:
Option 1 – Front Loaded Investment
This is based on replacing the traffic signals that have passed the 20 year design life and have gone over the 15 point threshold in year one, then year 2 addresses the remaining sites that have gone over the 15 point threshold with the following years just targeting sites as and when they go past their 20 year design life.
Option 2 – Worst First, Budget limited
This is based entirely on the worst scoring sites on the lifecycle planner with a target expenditure of £1m per year. This will not tackle the going problem of an aging asset.
It should be noted that other avenues of funding are also used for the replacement of traffic signal infrastructure with developer funding and major scheme funding being the main sources.