Part 2: Assessing the condition of the state highway network and structural assets

New Zealand Transport Agency: Maintaining and renewing the state highway network – follow-up report.

Our first report concluded that NZTA regularly assesses the general condition of the network’s surface. For example, it assesses the skid resistance and pavement strength of the network.

However, we found that NZTA needed to do more to bring together information about the condition of all structures on the network (such as bridges, tunnels, and retaining walls). We recommended that NZTA introduce, as a priority, a new information system for collating and recording information about all of the network’s structural assets and their condition. Because of the risks associated with tunnels, we also recommended that NZTA review its policy for inspecting structures to ensure that it contained a consistent and appropriate approach to tunnels.

New system for collating and recording information about all structural assets

NZTA told us that it has not yet implemented a new information system for structural assets. It said that a lack of resourcing has delayed the work.

However, NZTA is in the process of procuring a new system. It has carried out a Request for Information process, prepared a business case, drafted high-level requirements, and investigated several systems.

Review of policy for inspecting structures

Since our first report, NZTA has implemented a formal policy for inspecting tunnels. The policy sets out the main roles and responsibilities of the various parties involved in ensuring that the 16 tunnels on the network are safe and effective. The policy also sets out the requirements for inspecting the tunnels. The policy is consistent with our recommendation that NZTA review its policy for inspecting structures.

NZTA has also:

  • developed and issued a Tunnels Guide to supplement the Australian Tunnels Standard and Austroads Guide;3
  • carried out quantitative risk assessments for the Homer, Lyttelton, and Mount Victoria tunnels;
  • appointed tunnel managers for each tunnel and an independent safety manager to reinforce tunnel safety requirements; and
  • purchased a specific asset management system for tunnels that has been implemented for one tunnel in Auckland. Other information is now being put into the system.

Condition rating system for bridges

As part of its response to our recommendations set out in paragraph 2.2, NZTA decided to introduce a condition rating system for bridges. The rating system is consistent with the International Infrastructure Management Manual - 2011 Edition produced by NAMS.4 NZTA stores the ratings information in the bridge database that we describe in paragraph 2.34.

Broadly, a condition rating system involves defining an asset’s condition against a scale, which is typically 1-5. A rating of “1” means that the asset is in very good condition and requires only normal maintenance. A rating of “5” means that the asset is unserviceable and that more than half of the asset requires replacement.5 The asset’s rating can then be used to estimate the appropriate type and timing of maintenance or rehabilitation during the planning period, as well as the asset’s remaining useful life and replacement programme. The rating can also be used to determine current or future funding requirements.6

NZTA told us it has found that the rating system is not particularly useful as a way to determine the condition of a bridge. This is because:

  • a condition rating system is based solely on visual inspections and does not include more detailed engineering investigations and evaluations;
  • it is difficult to see how the 1-5 condition rating system can adequately cover the condition of a bridge during its life cycle; and
  • a lot of important variables are not included in the model (for example, the model cannot predict the future deterioration or structural implications of design faults, different environmental conditions, traffic management, or different construction materials).

Because of these problems, NZTA has decided to replace the condition rating system with an “engineering condition assessment”.

This approach involves regularly inspecting each bridge to accepted engineering standards. An experienced engineer then carries out more detailed investigations to produce optimised treatments and prioritised medium-term and long-term maintenance and renewals programmes. The specific data collected depends on the structural form and material type of each bridge. However, in general terms, it involves identifying current defects, assessing those defects to determine the optimal treatment type and timing, and identifying or forecasting future defects that might occur.

It is important that NZTA has a reliable system for determining the condition of bridges to allow it to monitor their condition and to plan for appropriate maintenance and rehabilitation treatment during their life. In our view, the system also needs to enable NZTA to rank its assets according to the priority need for investment in those assets.

Gathering and storing information about maintenance, renewals, and capital works

NZTA’s Highway and Network Operations Group has two main inventory databases: the Road Assessment and Maintenance Management (RAMM) database and the Bridge Data System database. For our limited follow-up work, we chose to sample data in the RAMM database.

The RAMM database contains detailed information about the road pavement and other related assets. The Bridge Data System database contains information about bridges, tunnels, and other structures.

When we carried out our first audit, independent network management consultants and physical works contractors were responsible for gathering, collating, and maintaining information in the RAMM database. Regional bridge consultants were responsible for gathering information about bridges and providing it to NZTA, which then entered it into the Bridge Data System database.

Our first report concluded that there was a high degree of variability in the completeness of information in the databases. This was because those responsible for providing the information did not always provide NZTA with timely, complete, and quality information about completed work. Accordingly, NZTA needed to ensure that external parties provided timely and complete information about the works carried out on the network. NZTA also needed to ensure that the information in the two databases was as complete and up to date as possible.

Also, NZTA needed to ensure that those providing the information had their own quality assurance systems and validation procedures, and were appropriately certified.

Providing timely and complete information

NZTA has introduced, or is in the process of introducing, some new procedures for ensuring that information contained in the RAMM database is complete, accurate, and reliable. For example, the new Network Outcomes Contracts require the primary supplier (that is, the party contracted to provide the maintenance and renewals services) to provide updates for the RAMM database monthly, rather than quarterly or annually. NZTA has requested suppliers that are not on Network Outcomes Contracts to do the same.

NZTA now has a new Network Outcomes Team in the National Office to deliver better strategic asset management, planning, and performance management. This includes introducing enhanced asset information collection requirements, monitoring, and analysis.

The Network Outcomes Team carries out RAMM database health checks to improve the quality of data. The checks will provide a snapshot of the completeness of RAMM data and establish a baseline against which improvements can be made. The checks will highlight:

  • the data for each network area contained in the database;
  • how current the RAMM data is; and
  • any gaps in the RAMM data.

The Network Outcomes Team also carries out a monthly reconciliation between expenditure on surfacing and pavement renewal, and activity as recorded in the RAMM database. The Network Outcomes Team provides this reconciliation to relevant NZTA staff each month to alert them to gaps in the information.

In addition, the new Network Outcomes Contracts (see Part 4) place stringent requirements on the primary supplier to prepare and comply with a data quality plan.

Contract penalties may apply if timely and accurate information is not provided.

Information in the RAMM database

Our limited sampling of the information in the RAMM database shows that it still contains substantial gaps in data. This means that the changes NZTA has put in place have not yet had the desired effect on data quality.

For example, Figure 1 shows pavement renewals for four different regions from
1 June 2013 to February 2014, as reported in the RAMM database. Figure 1 shows that actual renewals (202km) were significantly lower than target (692km) for the period. NZTA documents show that the discrepancy was caused by a lack of reporting rather than low performance.

Figure 1
Pavement renewals for four different regions at February 2014

February 2014
Target km (year to date)
February 2014
Actuals (RAMM)km (year to date)
SH Auckland 106 64 -42 60
SH Hamilton 191 93 -98 48
SH Wellington 179 43 -136 24
SH Christchurch 216 2 -214 1
Total 692 202 -490 29

Source: Redrawn from a table supplied by NZTA.

We also reviewed NZTA information showing cumulative carriageway length of resealing or second-coat sealing for 24 regions from July 2013 to June 2014.

During that period, no resealing or sealing was reported for 13 regions. Again, NZTA documents show that this reflects substantial gaps in data rather than no work being done.

It is essential that the RAMM database contain complete and accurate information. Such information allows NZTA to determine the current status and condition of its assets and to make informed asset management decisions, including how to prioritise spending.

Complete and accurate information in the RAMM database is also important because:

  • one of the main findings of the Taskforce was the need for improved asset management, which requires accurate, complete, and timely updates to the RAMM database;
  • the RAMM database is used to value the network for financial reporting purposes; and
  • the RAMM database is used for management reporting to the NZTA Board.

NZTA accepts that information contained in the RAMM database is incomplete and has now placed a high priority on improving it. For example, we reviewed the 2014/15 draft business plan of NZTA’s Performance Management Team, which lists its first priority as improving data quality.

Quality assurance systems for the RAMM database

The new Network Outcomes Contracts and NZTA’s State Highway Database Operations Manual (the Manual) provide primary suppliers with detailed instructions about the type of information that should be entered into the RAMM database, and how and when it should be entered.

The Manual provides:

  • for all RAMM database users to be certified;
  • that all RAMM database users should have their own internal quality assurance system;
  • for field validation procedures to ensure that RAMM database users submit accurate data; and
  • a process for RAMM database users to check the information they have entered and provide the results to NZTA.

We consider that NZTA has put in place clear and regular requirements for primary suppliers to validate asset information. NZTA also requires those providing the information to be appropriately certified.

Information in the Bridge Data System database

We did not need to test information contained in the Bridge Data System database. This was because NZTA acknowledged the limitations of that database, and the consequences for data quality. For example:

  • It has limited functionality and does not allow for inspection and work programmes to be stored.
  • Regional bridge consultants, who collect the information, cannot access the database and have to send the information to NZTA for uploading. This has resulted in some data entry errors.
  • Because regional bridge consultants are unable to access the Bridge Data System, they might be unaware of all relevant information about an asset.
  • To fill the gaps in information, regional bridge consultants have developed their own information systems, which are available only to them. The information might be lost if a regional bridge consultant’s contract is not renewed.

NZTA told us that implementing the new information system for structures (see paragraphs 2.3-2.5) should solve these problems.

3: Austroads is the Association of Australian and New Zealand road transport and traffic authorities. It provides expert technical input to national policy development on road and road transport issues.

4: The NAMS group is a New Zealand based organisation that develops asset management best practice publications, knowledge, and services.

5: Condition rating systems have been introduced in all Australian states, the United Kingdom, and the United States of America.

6: NZTA’s Bridge Condition Indicator Guide provides more details on how a condition rating system applies.

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