Following the studies of the Objectives and Main Characteristics File (DOCP), a consultation on the project to extend line 1 to Val de Fontenay was organised, in accordance with the Environmental Code.

On 4 June 2014, the National Commission for Public Debate (CNDP) recommended the organisation of a consultation with the public, under the aegis of an independent person who would be the guarantor. On 2 July 2014, it appointed Mrs Claude Brévan as guarantor of the consultation.

The consultation took place from 10 November 2014 to 10 January 2015. Its objectives were to:

• To inform the inhabitants, elected officials and economic and associative actors of the municipalities crossed about the project
• To exchange with the latter in order to listen to their opinion and to enrich the project according to their proposals

As part of the preliminary consultation, three route variants were submitted to the public for opinion. This consultation has generated a significant and rich participation of residents, users and stakeholders from all territories.

On 8 July 2015, the Board of Directors of Île-de-France Mobilités (then Syndicat des Transports d'Île-de-France – STIF) adopted the results of the consultation on the extension of line 1 to Val de Fontenay, giving all the opinions expressed through the website, the T maps and the public meetings. The report takes into account the lessons learned from the consultation and takes note of the report drawn up by the guarantor of the consultation.

The Board of Directors of Île-de-France Mobilités then decided to continue the studies on the basis of:

• Two variants of the resort Les Rigollots, and to propose at the end of the schematic diagram, the variant chosen
• A terminus station to the east of the Val de Fontenay station, a factor in the good performance of the extended line 1 and guaranteeing a good quality of connection
• A deepening of route 1 passing through the Grands Pêchers intermediate station and the alternative route serving the Verdun crossroads and allowing a terminus at Val de Fontenay East, then to propose within the framework of the principle diagram the chosen variant.

Between the 2014 consultation and the 2022 public inquiry, the dialogue with the territory continued as the studies progressed.
At the monitoring committee meeting of 19 October 2016 bringing together the partners and elected officials concerned by the extension, Île-de-France Mobilités presented the conclusions of the studies on intermediate station variants carried out with RATP. The choice of the route passing through the Grands Pêchers station was retained by all the partners for the continuation of the schematic studies.
These studies aimed to deepen the solution chosen among the different variants. At the same time, the local authorities concerned by the route have been involved in regular exchanges.
All of these discussions, which were carried out in parallel with the conduct of the studies, led Île-de-France Mobilités and RATP to optimise the project presented in consultation, through several changes, without modifying the main characteristics of the project.