I have blogged previously about a French presidential decree in 2012 that mandated that all of France's critical underground utility infrastructure must be mapped in 3D to an accuracy of 40 cm (about 16 inches). Critical infrastructure according to the decree includes buried electric power cables, pipelines, and public transport infrastructure, but not buried water and telecommunications infrastructure. The deadline for urban areas is January 1, 2019 and for non-urban areas January 1, 2026.
Responsibility for mapping underground infrastructure
The national regulation requiring mapping of subsurface infrastructure titled Decree relating to excavations near underground, overhead or underwater transmission or distribution networks was promulgated on 15 February 2012. The "anti-network damage" reform, known as "DT-DICT", came into effect on 1 July 2012. (DT is a notice on intended construction work sent by the contractor to the operator of the network. DICT is a notice of intention by the contractor to start work.) It requires owners and managers of critical infrastrructure networks to make a commitment about accurately locating their works. The responsibility for implementing the decree lies with a "competent local authority" which is not defined in the decree. Across France different departmental organizations have taken responsibility for implementing the decree. For example, in the Ardèche Département in the southeast of France, the Syndicat Départemental d'Energies de l'Ardèche, the Energy Agency of the Ardèche Département, has claimed responsibility for implementing the decree because it is responsible for electric power distribution and street lighting to the 339 municipalities in the Département and because it has already carried out a cadastral mapping project.
The deadlines for certification and mapping subsurface critical infrastructure are as follows:
- By January 1, 2018, supervisors of construction projects and building sites, heavy equipment operators, and subsurface utility mapping professionals must be certified to conduct operations near underground infrastructure. This requires a governmental authorization designated AIPR (Authorization to excavate near underground infrastructure.)
- As of January 1, 2018 managers of construction projects are required to use certified service providers for two types of services; resurveying existing underground infrastructure encountered during construction when the reported location is inaccurate and mapping new infrastructure.
- By January 1, 2019 the appropriate authority at the departmental level is required to have compiled a geographic basemap and to have accurately mapped the routes of all critical infrastructure in urban areas. For critical infrastructure networks outside urban areas, the deadline is 1 January 2026.
The decree distinguishes critical infrastructure for public safety, critical infrastructure for the economy and non-critical infrastructure. Critical infrastructure for public safety includes
- pipelines carrying liquid or liquefied hydrocarbons, combustible and other hazardous gases, steam, and heated water
- electric power lines and public lighting networks
- public transport infrastructure
- sewer lines under pressure
- flood prevention structures
Infrastructure that is not considered to be critical for public safety include,
- telecommunications cables and low voltage power lines and public lighting network
- drinking water and industrial water supply or fire protection
- sanitary and storm sewers
Telecommunications cables and facilities are considered to be critical economic infrastructure, but not critical for public safety.
Buried networks that are critical according to these definitions and located in urban areas will have to be georeferenced in the national system of coordinates with class A accuracy, in other words to 40 cm or better, by 1st January 2019. Implementation of this mandate for all critical infrastructure networks on the national territory of France must be completed by 2026. (Les réseaux sensibles enterrés, situés en unités urbaines, devront être géo référencés dans le système national de coordonnées en classe A au 1er janvier 2019 et que ces exigences seront applicables à ces mêmes réseaux sur l’ensemble du territoire national à l’horizon 2026.)
Accuracy of location of underground structures and liabilities for construction projects
Project managers of proposed construction projects are required to send a DT which is a statement of the proposed work including a polygon delineating the area affected to the operators of utility networks operating in the area. In return operators of utility networks must provide the project managers maps of their underground networks in the area indicating the accuracy of the geographical location of different structures of their networks classified according to three accuracy classes.
Class A: if the maximum uncertainty of location indicated by the utility operator is less than or equal to 40 cm
Class B: if the maximum uncertainty of location indicated by the utility operator is greater than that for Class A and less than or equal to 1.5 meters
Class C: if the maximum uncertainty of location indicated by the utility operator is greater than 1.5 meters , or if the operator is not able to provide the location.
The Decree states that uncertainty in the geographical location of a structure is considered likely to jeopardize the construction project or significantly impact the technical or financial conditions of its implementation when the accuracy of the geolocation of the structure is classified B or C. For structures falling in these accuracy classes, the utility operator is required to initiate a process to reduce this uncertainty and achieve class A as quickly as possible.
Furthermore, if further investigation (typically potholing) of some structures by the contractor is required, the cost of the investigations is assigned as follows
- The construction contractor assumes the entire cost when the structures have been assigned by the operator to accuracy class B and further investigation reveals that the actual classification is found to be Class B or Class A
- Half of the cost of the investigation is to be borne by the operator when the structures are assigned by the operator to accuracy class C;
- All of the cost is to be borne by the operator when the structures have been assigned by the operator to accuracy class B and when the result of further investigation reveals that the actual classification is accuracy class C
Surveying underground infrastructure for construction projects
For construction project reporting, contractors are required to survey all new and changed underground structures. These surveys must satisfy certain conditions. Location coordinates of structures in an open trench must be surveyed by a certified provider (see above for certification). If remote detection technology such as GPR is employed, the firm performing this work is not required to be certified, but a certified provider must be involved in georeferencing the data. Whatever the method of measurement used , direct or remote, the accuracy of the locations of new or changed structures reported by the contractor must be accuracy class A, in other words 40 cm or better. For each structure the data recorded must include the name of the project manager of the site, the name of the company that provided the location information, the name of the certified provider responsible for determining the location of each structure, the maximum measurement uncertainty (for x, y, and z ), and in the case of remote detection such as GPR or EMI, the type of measurement technology used. Presumably this information would be used to assign liabilities in the case that it is determined later that inaccurate location data was reported. This data must be shared with the operator or operators of the networks affected.