In France a national system for reducing damage to underground utilities during construction was initiated in 2013. The key features of the system are the requirement to notify utilities with the details of a proposed construction project during the planning phase, a process that improves location accuracy of existing underground infrastructure, mandatory reporting of incidents of damage, and the Observatoire national DT-DICT which publishes annual statistics. The annual statistics include the number of projects, the number of damage incidents and the ratio expressed as a percentage of damages per project. The statistics show that while the number of projects has increased since 2013 by about 25 %, the damage per project has decreased from 0.42 % in 2013 to 0.26% in 2020. This represents a significant decline in underground damage even though construction activity has increased.
Background
In early 2000, the French government investigated damages in utility networks, of which there are something like 60,000 incidents every year. It found that the average direct cost of each damage incident was roughly 1,000 euro, the total cost including direct+indirect+social costs was estimated to reach 32,000 euro for each damage incident, and in addition there were injuries and fatalities to workers and the public. The total cost to the French economy is estimated to be on the order to two billion euros annually. According to professionals involved in public construction project, the main causes of incidents of damage to utility networks are unreliable information about the location of underground utility networks, lack of practical and efficient tools to measure accurate locations for underground utilities, and the inability to provide real-time visualization for underground utilities.
After many very serious accidents involving fatalities in the late 2000s, the government began an initiative entitled Construire sans détruire (Building Without Destroying.) In 2011 this resulted in damage reduction regulations. It required the implementation of an online service where all network operators were required to to provide information about their overhead, underground and underwater utilities including their location. Furthermore they were required to classify all of their network equipment according to three quality classes. The target class is Class A which means that the location of the network facility is known with an accuracy better than 40 cm for rigid equipment like pipes and better than 50 cm for flexible facilities like cables. Class B is assigned to network equipment whose location is known to an accuracy between 40 cm and one meter. Class C is assigned to equipment who location is either not known or is known to an accuracy of one metre or lower. The objective for achieving the Class A quality standard for all critical infrastructure (gas, electric power, hazardous fluids and water under high pressure) in urban areas was 2020. The target for all critical infrastructure in urban and non-urban locations is 2026. The target for knowing the location of all network infrastructure in France to 40 cm or better in 2032.
The DT - DICT system
At the inception of a construction project the project manager is required to prepare a DT (Déclaration de projet de travaux) a standardized document where the construction project is described. It can be submitted online or on paper. Among other things it involves drawing a map of the proposed construction site which can be a shape file or a sketch on paper. Once the DT is submitted all the operating companies who own network facilities in the area, have nine days to provide maps showing the location of their network equipment with the quality level (A,B, or C) assigned to each piece of equipment. The project manager will likely receive a response from 8 -12 network operating companies including electric power, gas and fuel, clean water, waste water, telecom, and other utilities.These responses enables the project manager when planning and designing the project to know where underground infrastructure is located and the reliability of the data. Unfortunately current regulations do not restrict the way this information is provided to the project manager and they can take the form of paper, PDF or a variety of digital vector formats.
When a project has reached the stage of excavation, the project manager must submit a second document referred to as DICT (Déclaration d'intention de commencement de travaux) declaring the intention to begin work. The DICT provides a detailed schedule of the planned construction work. In response to the DICT the network operating companies are required to notify the excavator of any changes to the network since the submission of the DT. They also are required to verify the technical compatibility of the project with the existing networks and check the technical safety recommendations.
The objective of the DT DICT system is to provide the project manager with maps of all underground utilities accurate to 40 cm or better (Class A). One of key activities of the project manager is to review the quality levels assigned to all the network facilities in the construction area to identify any equipment that has not achieved Class A. For any equipment assigned B or C Class, the project manager may require additional investigation to precisely position the network equipment to achieve Class A. There are rules for who is responsible for funding the extra investigations. For equipment that is assigned Class B, the project is responsible for covering the cost of any further locate work. For equipment assigned Class C, the network operator and the project split the cost of additional locate operations 50%/50%. If it is suspected or revealed that the maps provided by the network operator are wrong, the operating company must perform and cover the cost of additional investigations to locate the noncomplisnt equipment accurately.
Impact of the DT DICT system on underground damage
The DT DICT system has been operational since 2013. One of the requirements of the regulations is that it is mandatory to report all incidents of underground damage. Based on these data statistics are compiled and published annually for the Observatoire national DT-DICT. There are several things to notice in these statistics. First of all construction activity has increased by about 25 % since 2013. Secondly in 2020 most of the submissions were made online. Only 7 % of the DT submission were manual, and these were probably made my relatively small operators.
| Year | Projects | Damage rate | Submitted online |
| 2013 | 4,502,440 | 0.42% | 29% |
| 2020 | 5,628,251 | 0.26% | 93% |
Since the DT DICT system was implemented, the damage rate prorated to construction activity (number of damage incidents per project) has decreased. The damage rate in 2013 was 0.42%. Seven years later, the statistics show that the damage rate has decreased to 0.26% which represents a large improvement. This contrasts with the damage rates for one call systems in the Netherlands, United States, and Ontario which have remained nearly constant for the last few years,
One of the important features of the DT DICT system that differentiates it from one call systems is that the process improves the quality of the records maintained by network operators. That together with the requirement of notifying all affected utilities of planned construction projects are probably the most important reasons for the decline in the rate of underground damage.
Challenges
The DT DICT system places heavy responsibilities on the construction industry. These include the preparation and management of complex documents, challenging scheduling, especially for surveyors, risk of delays, and increased demand for surveyors because of the high accuracy required by the DT DICT system. This is occurring at a time where there is already a shortage of surveyors in France.
The challenge for surveyors is to increase productivity. One way is to avoid site visits whenever possible. Modern technology in the form of a smartphone and GNSS+RTK makes it possible for the construction crew to record the location of newly installed or exposed underground utilities. The collected data can be reviewed later in the office by a certified surveyor. The new technology makes it possible for contractors and network operators to comply with the DT DICT regulations without adding significantly to costs.
The future of utility surveying is that the certified surveyor no longer needs to travel to construction sites. The location of utilities in open trenches can be recorded to survey accuracy and uploaded by the construction crew who are already onsite. With modern LiDAR and photogrammetric technology it is possible to record a point cloud of the open trench which can be stored in the cloud and contains much more information than a traditional set of survey points. If the location of all the underground utilities in the proposed construction site is Class A, known to 40 cm accuracy or better, augmented reality technology provides a reliable way of visualizing this data in the field on a handheld device.
This post is based on Patrice Lemire's talk at the Subsurface Utility Mapping Strategy Forum (SUMSF). Patrice Lemire is the Managing Director of Geosystems France.
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