<figure><img src="image_1.png" /></figure>

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# Accessibility data of the island of Nantes

Nicolas Roelandt, F. Serhan Daniş, Valerie Renaudin, Min Wang, Thomas

Leysens, Olivier Dumas

<figure><img src="image_2.png" /></figure>

## To cite this version:

Nicolas Roelandt, F. Serhan Daniş, Valerie Renaudin, Min Wang, Thomas Leysens, et al., Accessibility data of the island of Nantes. 2025. hal-05156851

HAL Id: hal-05156851

https://univ-eiffel.hal.science/hal-05156851v1

Preprint submitted on 10 Jul 2025

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Distributed under a Creative Commons Attribution - ShareAlike 4.0 International License
# Accessibility data of the island of Nantes

Nicolas Roelandt
Univ. Eiffel/AME

F. Serhan Daniş
Univ. Eiffel/GEOLOC

Valérie Renaudin
Univ. Eiffel/GEOLOC

Min Wang
Univ. Eiffel/GEOLOC

Thomas Leysens
Univ. Eiffel/AME

Olivier Dumas
Nantes Métropole

2025-07-07

## Value of the data

* this data is rare, as it is the first standardized geospatial dataset dedicated to accessibility to be created by public authorities in France

* this data will be useful in helping disabled people to plan their journeys, and in assisting the development of disability-specific route planners

* although have been provided for research purposes, this data gives a glimpse of what the CNIG Accessibility geostandard will look like.

## Background and motivation

In 2025, pedestrian navigation remains underdeveloped, with no dedicated databases available. Databases, whether public like BD TOPO from the French National Geographic Institute (IGN), private like the Here Maps (formerly Navteq), or collaborative like OpenStreetMap (OSM), focus on automobile traffic. Efforts are underway to take disability and pedestrian navigation into account in the OSM database, but most of the time only the presence of sidewalks along the road is indicated.

Yet pedestrian paths are used not only by able-bodied users, but also by the disabled. Developing navigation services that take into account the specific needs of the disabled requires the more detailed information on the environment such as sidewalk width, slopes and obstacles. Since 2019, the Mobility Orientation Act requires municipalities and inter-municipal public establishments in France to collect data on the accessibility of people within a 200-meter radius of priority stops as defined by the Transportation Code, to enable the development of guidance tools that take into account all disability families.

In 2020, this law led to the creation of a working group dedicated to accessibility, by the Ministerial Delegation for Accessibility (DMA) of the Ministry of Ecology and Transport. Also attached to the Data Commission of the National Council for Geographic Information (CNIG), the working group defined a standard for geospatial data collection dedicated to accessibility, the first version of which was published in 2021.
The Accessibility standard has been developed taking into account the European NeTEx standard, dealing with the exchange of public transport information such as stops, networks, timetables, and feedback from work carried out in 2018 and 2019 as part of the “GIS & Accessibility” partnership between Center for Studies and Expertise on Risks, the Environment, Mobility and Development (CEREMA), the local authorities of the Grenoble Alpes Métropole, Lorient Agglomération and Toulouse Métropole. Its aim is to describe data on the movement chain for people with reduced mobility or disabilities in public spaces, on roads and in establishments open to the public. The CNIG standard is accompanied by a comprising 18 GeoPackage files and a QGIS project.

Visually impaired people use different landmarks from the general population, favoring tactile and sound cues M. Wang, A. Dommes, V. Renaudin, and N. Zhu [1]. Several initiatives aim to help the visually impaired prepare their itinerary G. Touya, S. Braikeh, R. Campbell, J.-M. Favreau, and J. Kalsron [2], J. Kalsron, J.-M. Favreau, and G. Touya [3] with the help of a mobility instructor. In 2021, GEOLOC Laboratory and Okeenea Digital partnered in a LabCom<fnref n="1" /> project, called INMOB, dedicated to the mobility of people with disabilities and aims to allow the creation and sharing of theoretical and experimental skills in order to meet the challenges and needs of new mobility services, especially for visually impaired people in urban environments. Several works undertaken by the LabCom relies on a navigation graph (M. Wang, F. S. Daniş, V. Renaudin, and M. Serviéres [4]; F. S. Daniş, M. Wang, and V. Renaudin [5]) and the location of landmarks (see M. Wang, A. Dommes, V. Renaudin, and N. Zhu [1]) to refine the subject’s location. While open data includes some of these landmarks, such as buildings, crosswalks, certain obstacles) within the Nantes Metropole, a graph dedicated to pedestrian mobility was lacking, particularly considering sidewalks.

## Data description

LabCom INMOB chooses the city of Nantes as the urban setting for its experiments. As seen in Figure 1, the specific area of the dataset is located on a river island called “Île de Nantes” surrounded by two arms of the Loire river, the Madeleine arm to the north and the Pirmil arm to the south. It lies to the south of the city of Nantes, bordering the communes of Rezé and Saint-Sébastien-sur-Loire.

<footnote n="1">¹Joint laboratories between research organizations and SMEs or intermediate-sized enterprises (Labcom).</footnote>
<figure><img src="image_4.png" /><figcaption>Figure 1: Situation map</figcaption></figure>

The dataset is a single GeoPackage file containing 7 layers:

- bridge.adm_quartier_s ( 1 features)

- escalier ( 29 features)

- stationnement_pmr ( 62 features)

- traversee ( 383 features)

- noeud_cheminement ( 1058 features)

- obstacle ( 1788 features)

France has a set of legal coordinate reference systems for all its territories. The use of these coordinate reference systems is mandatory for the transmission of localized data by and for the public administration. RGF93/Lambert93 has been the projected reference system valid for mainland France. However, the extent of Lambert93 leads to linear deformations. For precision work, it is possible to use one of the so-called Lambert93 9-zone projections. These are flat projections centered on parallels running from the 42nd to the 50th degree north. Each zone has an area of one degree north and south of the parallel. As RGF93 v1 / CC47 designates zone 6, centered on the 47th parallel, within which the city of Nantes is located, all the coordinates used in the dataset follow the RGF93 v1 / CC47 coordinate reference system. Dimensions of features are in metric units with a centimeter resolution.
All layers have a `OBJECTID` field which stores a unique identifier of the features. It does not share information otherwise, so this field won't be described below. Same goes for the `geom` variable as the geometry type of the features is explicit.

<table><caption>Table 1: Layers general description</caption><thead><tr><th>name</th><th>geom-type</th><th>features</th><th>fields</th><th>crs</th><th>short_description</th></tr></thead><tbody><tr><td>bridge.adm_quartier_s</td><td>Polygon</td><td>1</td><td>14</td><td>RGF93 v1 / CC47</td><td>Administrative contour</td></tr><tr><td>escalier</td><td>Point</td><td>29</td><td>14</td><td>RGF93 v1 / CC47</td><td>Stairs</td></tr><tr><td>stationnement_pmr</td><td>Point</td><td>62</td><td>13</td><td>RGF93 v1 / CC47</td><td>Parkings for disabled persons</td></tr><tr><td>traversee</td><td>Point</td><td>383</td><td>13</td><td>RGF93 v1 / CC47</td><td>pedestrian crossings</td></tr><tr><td>noeud_cheminement</td><td>Point</td><td>1058</td><td>6</td><td>RGF93 v1 / CC47</td><td>Waypoints</td></tr><tr><td>obstacle</td><td>Point</td><td>1788</td><td>12</td><td>RGF93 v1 / CC47</td><td>Obstacles</td></tr><tr><td>troncon_cheminement</td><td>Line String</td><td>1795</td><td>10</td><td>RGF93 v1 / CC47</td><td>Pathways</td></tr></tbody></table>

As Table 1 shows, most layers are of the Point type, with the exception of pathways (which are Linestrings) and the study area polygon.

Most fields are coded with 2 characters ranging from `00` to `99`. Several lists exist to decode these characters, for example: `état` (condition), `coté` (side), etc. A dictionary of those coded values is available in part 3.5 "Description des types énumérés" of the standard (@2021AccessibiliteCNIG).

Some variables present in the standard are absent from the dataset supplied. This is either because they have not been collected (since they were collected before the standard was written) or because they were forgotten when the data was formatted. These missing variables will be indicated.

Whenever possible, a snapshot of one of the entities is displayed, extract from the Panoramax project, together with the associated data.

The companion notebook describes the different layers and their discrete and continuous variables in greater detail.

### `bridge.adm_quartier_s`

This layer corresponds to the study area mask. It is not one of the layers defined by the CNIG Accessibility standard. It was sent to us by Nantes Métropole. The layer contains only one feature,
the outline of the Ile de Nantes. The various variables present correspond to creation and update dates of this feature.

<table><caption>Table 2: Numerical variables summary</caption><thead><tr><th>skim_variable</th><th>n_missing</th><th>complete_rate</th><th>min</th><th>max</th><th>median</th><th>n Unique</th></tr></thead><tbody><tr><td>date_creazione_bd</td><td>0</td><td>1</td><td>1996-01-25 14:52:00</td><td>1996-01-25 14:52:00</td><td>1996-01-25 14:52:00</td><td>1</td></tr><tr><td>date_modificazione_bd</td><td>0</td><td>1</td><td>2018-06-04 10:46:44</td><td>2018-06-04 10:46:44</td><td>2018-06-04 10:46:44</td><td>1</td></tr><tr><td>date_creazione</td><td>0</td><td>1</td><td>2021-10-21 12:00:45</td><td>2021-10-21 12:00:45</td><td>2021-10-21 12:00:45</td><td>1</td></tr><tr><td>date_modificazione</td><td>0</td><td>1</td><td>2021-10-21 12:00:45</td><td>2021-10-21 12:00:45</td><td>2021-10-21 12:00:45</td><td>1</td></tr></tbody></table>

## escalier

This layer corresponds to the staircases identified during data collection.

* Available variables

* idescalier: unique identifier

* largeurUtile: Usable sidewalk width (in meters)

* nbMarches: Number of steps

* nbVoleeMarches: Number of flights of stairs

* hauteurMarche: Step height (in meters)

* giron: Tread length (in meters)

* etatRevetement: coating condition

* mainCourante: Presence or absence of a handrail

* dispositifVigilance

* prolongMainCourante

* mainCouranteContinue

* contrasteVisuel

* Supplementary variables

* id_troncon

As stairs are pathways, they are related to the corresponding feature by the id_troncon.
<table><caption>Table 3: Numerical variables summary</caption><thead><tr><th>skim_vari-<br>able</th><th>n_miss-<br>ing</th><th>com-mean<br>plete_rate</th><th>sd</th><th>p0</th><th>p25</th><th>p50</th><th>p75</th><th>p100</th><th>hist</th></tr></thead><tbody><tr><td>largeurUtile</td><td>0</td><td>1 1.40</td><td>0.00</td><td>1.40</td><td>1.40</td><td>1.40</td><td>1.40</td><td>1.40</td><td>■</td></tr><tr><td>nbMarches</td><td>29</td><td>0 NaN</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td></td></tr><tr><td>nbV-<br>oleeMarches</td><td>29</td><td>0 NaN</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td></td></tr><tr><td>hauteur-<br>Marche</td><td>0</td><td>1 0.17</td><td>0.01</td><td>0.14</td><td>0.17</td><td>0.17</td><td>0.17</td><td>0.17</td><td>■</td></tr><tr><td>giron</td><td>0</td><td>1 0.30</td><td>0.13</td><td>0.28</td><td>0.28</td><td>0.28</td><td>0.28</td><td>1.00</td><td>■</td></tr></tbody></table>

<figure><img src="image_5.png" /></figure>

<figure><img src="image_6.png" /><figcaption>Figure 2:</figcaption></figure>

<table><thead><tr><th>OB-<br>JEC-<br>TID</th><th>idescali<br>con<br>eta-<br>tRevet<br>ment ante<br>ilance</th><th>main dis-<br>chargeu<br>positifV<br>gaste-r-U<br>Visueltile</th><th>main-<br>Cour-<br>ante-<br>Continue</th><th>nbMarches<br>long-<br>Marche</th><th>nbV-<br>hgamma<br>Marche teur-<br>Marche</th><th>geom</th></tr></thead><tbody><tr><td>84</td><td>44109:ES-062094<br>C:1629194:LO</td><td>NA 05 05 1.4</td><td>NA</td><td>NA</td><td>NA</td><td>0.10.28<br>POINT (1355113<br>6233071)</td></tr></tbody></table>

### stationnement_pmr

Parking spaces reserved for people with disability or reduced mobility.

* Available variables

* idstationnement : unique identifier

* typeStationnement : Type of parking (angled, parallele, perpendicular)

* etatRevetement : wear and tear of the pavement affecting walkability
* largeurStat : parking space width

* longueurStat : parking space length

* banLatSecurite : Presence of a secure side band for moving the person to the pedestrian walkway

* surLongueur : dimension of over-length on traffic lane

* signalPMR : presence of signs indicating PRM parking

* marquageSol : statutory road markings

* pente : slope in the longitudinal direction of the parking space

* devers : slope of the lot in the lateral direction of the parking space

* typeSol : surfacing material

<table><caption>Table 4: Numerical variables summary</caption><thead><tr><th>skim_vari-<br>able</th><th>n_miss-<br>ing</th><th>com- mean<br>plete_rate</th><th>sd</th><th>p0</th><th>p25</th><th>p50</th><th>p75</th><th>p100</th><th>hist</th></tr></thead><tbody><tr><td>largeurStat</td><td>0</td><td>1 3.05</td><td>0.12</td><td>3.0</td><td>3</td><td>3.0</td><td>3.00</td><td>3.3</td><td>■</td></tr><tr><td>longueurStat</td><td>0</td><td>1 5.59</td><td>0.94</td><td>4.2</td><td>5</td><td>5.1</td><td>6.48</td><td>7.8</td><td>■■■</td></tr><tr><td>banLatSecu-<br>rite</td><td>62</td><td>0 NaN</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td></td></tr><tr><td>surLongueur</td><td>62</td><td>0 NaN</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td></td></tr><tr><td>signalPMR</td><td>0</td><td>1 0.97</td><td>0.18</td><td>0.0</td><td>1</td><td>1.0</td><td>1.00</td><td>1.0</td><td>■</td></tr><tr><td>marquageSol</td><td>0</td><td>1 0.79</td><td>0.75</td><td>0.0</td><td>0</td><td>1.0</td><td>1.00</td><td>3.0</td><td>■■</td></tr><tr><td>pente</td><td>0</td><td>1 1.00</td><td>0.00</td><td>1.0</td><td>1</td><td>1.0</td><td>1.00</td><td>1.0</td><td>■■</td></tr><tr><td>devers</td><td>0</td><td>1 1.45</td><td>0.84</td><td>1.0</td><td>1</td><td>1.0</td><td>1.00</td><td>3.0</td><td>■</td></tr></tbody></table>

<figure><img src="image_7.png" /><figcaption>(a) Example of a stair flight</figcaption></figure>

<figure><img src="image_8.png" /><figcaption>(b) Location of the example
Figure 3:</figcaption></figure>
<figure><img src="image_9.png" /><figcaption>(a) Example of a crosswalk</figcaption></figure>

<figure><img src="image_10.png" /><figcaption>(b) Location of the example

Figure 4:</figcaption></figure>

<table><thead><tr><th>OB-JEC-TID</th><th>idtraverse</th><th>iron-con</th><th>etatRevetemar</th><th>ecartage</th><th> aide</th><th> repere</th><th> prchaussee</th><th> co-geom</th></tr></thead><tbody><tr><td>2936</td><td>44109:-</td><td>44109:TR-04</td><td>NA</td><td>02</td><td>01</td><td>0</td><td>01</td><td>NA</td><td>0</td><td>NA</td><td>NA</td><td>POINT<br>(1354596<br>6232943)</td></tr><tr><td></td><td colspan="10">TRA:191624191824:LOC</td></tr></tbody></table>

### noeud_cheminement

Waypoint in the pathway. These are junction points between pathways and don't have no physical reality.

Figure 5a shows the (fictitious) junction of two pedestrian crosswalks (in blue) and a section of pathway (in red).

* Available variables

* idnoeud: unique identifier

* controleBEV: tactile paving condition

* bandeEveilVigilance: visually and tactilely contrasting surface to signal danger

* abaisseTrottoir: distance over which the height of the kerb is reduced to its maximum, excluding ramps.

* Missing variables

* altitude: waypoint elevation

* hauteurRessaut: height of the vertical projection of the kerb

* abaissePente: slope due to inclination of sidewalk towards curb cut

* bandeInterception: presence of interception strip (optional)

* Supplementary variables

* id_noeud: unknown, not present in standard (possibly an export artifact)
<table><caption>Table 6: Numerical variables summary</caption><thead><tr><th>skim_variable</th><th>n_missing</th><th>complete_rate</th><th>com-mean</th><th>sd</th><th>p0</th><th>p25</th><th>p50</th><th>p75</th><th>p100</th><th>hist</th></tr></thead><tbody><tr><td>abaisseTrottoir</td><td>308</td><td>0.71</td><td>1.19</td><td>0.09</td><td>0</td><td>1.2</td><td>1.2</td><td>1.2</td><td>1.2</td><td>_________■</td></tr></tbody></table>

<figure><img src="image_11.png" /></figure>

<figure><img src="image_12.png" /><figcaption>Figure 5:</figcaption></figure>

<table><thead><tr><th>OB-JEC-TID</th><th>idnoeud</th><th>control-BEV</th><th>bandeEveil-Vigilance</th><th>id_noeud</th><th>abais-seTrottoir</th><th>geom</th></tr></thead><tbody><tr><td>5920</td><td>44109:N-OD:8928:LOC</td><td>02</td><td>02</td><td>8928</td><td>1.2</td><td>POINT (1354602 6232944)</td></tr></tbody></table>

## obstacle

* Available variables

* idobstacle : unique identifier

* typeObstacle : nature of the element located in the passage

* largeurUtile : usable passage width at obstacle location

* positionObstacle : position of element in passage

* longueurObstacle : length of obstacle in direction of travel

* reperabiliteVisuelle : visual contrast between the obstacle and its surroundings

* rappelObstacle : presence of an obstacle warning element

* largeurObstacle : width of obstacle on the ground (optional)

* hauteurObsPoseSol : height from ground to top of obstacle (optional)
* hauteurSousObs: height from floor to bottom of overhead element (optional)

* Supplementary variables

* gid_ssf: unknown, not present in standard (export artifact ?)

<table><caption>Table 7: Numerical variables summary</caption><thead><tr><th>skim_vari-<br>able</th><th>n_min<br>ing</th><th>complete_rate</th><th>mean</th><th>sd</th><th>p0</th><th>p25</th><th>p50</th><th>p75</th><th>p100</th><th>hist</th></tr></thead><tbody><tr><td>largeurUtile</td><td>0</td><td>1</td><td>1.36</td><td>0.12</td><td>0.8</td><td>1.40</td><td>1.4</td><td>1.40</td><td>1.4</td><td></td></tr><tr><td>longueurOb-<br>stacle</td><td>0</td><td>1</td><td>12.96</td><td>25.41</td><td>1.0</td><td>1.00</td><td>1.0</td><td>14.00</td><td>269.0</td><td></td></tr><tr><td>reperabilite-<br>Visuelle</td><td>0</td><td>1</td><td>0.71</td><td>0.45</td><td>0.0</td><td>0.00</td><td>1.0</td><td>1.00</td><td>1.0</td><td></td></tr><tr><td>gid_ssf</td><td>0</td><td></td><td>22147.67</td><td>8408.453541</td><td>0.0757.751</td><td>2017.5</td><td>6870.25</td><td>3319.0</td><td></td></tr><tr><td>largeurOb-<br>stacle</td><td>1788</td><td>0</td><td>NaN</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td></td></tr><tr><td>hauteurOb-<br>sPoseSol</td><td>1788</td><td>0</td><td>NaN</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td></td></tr><tr><td>hauteur-<br>SousObs</td><td>1788</td><td>0</td><td>NaN</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td>NA</td><td></td></tr></tbody></table>

<figure><img src="image_13.png" /><figcaption>(a) Example of an obstacle (lamp post)</figcaption></figure>

<figure><img src="image_14.png" /><figcaption>(b) Location of the example</figcaption></figure>

<caption>Figure 6:</caption>
<table><thead><tr><th>OB-JEC-TID</th><th>idob-stacle</th><th>type largeur</th><th>position longitudinal</th><th>repart</th><th>rapport</th><th>hauteur</th><th>geometrie</th></tr></thead><tbody><tr><td>19712</td><td>44109:OB04</td><td>1.4</td><td>01</td><td>1</td><td>10960</td><td>NA</td><td>NA</td><td>POINT (1354530 6232937)</td></tr></tbody></table>

### troncon_cheminement

* Available variables

* `idtroncon`: unique identifier

* `longueur`: path length

* `from`: section start node identifier

* `to`: section end node identifier

* `typetronçon`: section type

* `statutVoie`: way type

* `pente`: most unfavorable slope in the direction of travel

* `devers`: worst-case slope, perpendicular to the direction of travel (departure node to arrival node)

* `accessibiliteGlobale`: Overall assessment of section accessibility

<table><caption>Table 8: Numerical variables summary</caption><thead><tr><th>skim_vari-able</th><th>n_miss-ing</th><th>com-plete_rate</th><th>mean</th><th>sd</th><th>p0</th><th>p25</th><th>p50</th><th>p75</th><th>p100</th><th>hist</th></tr></thead><tbody><tr><td>longueur</td><td>0</td><td>1</td><td>155.83</td><td>272.18</td><td>2</td><td>13</td><td>37</td><td>161</td><td>1568</td><td>■</td></tr></tbody></table>

<figure><img src="image_15.png" /><figcaption>(a) Example of a pathway</figcaption></figure>

<figure><img src="image_16.png" /><figcaption>(b) Location of the example</figcaption></figure>

<caption>Figure 7:</caption>
<table><thead><tr><th>OB-JEC-TID</th><th>type-tron-con</th><th>statut</th><th>ville</th><th>acces-vers</th><th>sibilite-globale</th><th>from</th><th>to</th><th>idtron</th><th>longueur</th><th>geom</th></tr></thead><tbody><tr><td>20220</td><td>18</td><td>02</td><td>2</td><td>3</td><td>03</td><td>44109:NOD-21800:NOC44109:TR-393<br>OD:8827:LOC191836:LOC</td><td>LINESTRING<br>(1354492<br>6232933...)</td><td></td><td></td><td></td></tr><tr><td>20220</td><td>18</td><td>02</td><td>2</td><td>3</td><td>03</td><td>44109:NOD-21800:NOC44109:TR-393<br>OD:8827:LOC191836:LOC</td><td>LINESTRING<br>(1354492<br>6232933...)</td><td></td><td></td><td></td></tr><tr><td>20220</td><td>18</td><td>02</td><td>2</td><td>3</td><td>03</td><td>44109:NOD-21800:NOC44109:TR-393<br>OD:8827:LOC191836:LOC</td><td>LINESTRING<br>(1354492<br>6232933...)</td><td></td><td></td><td></td></tr><tr><td>20220</td><td>18</td><td>02</td><td>2</td><td>3</td><td>03</td><td>44109:NOD-21800:NOC44109:TR-393<br>OD:8827:LOC191836:LOC</td><td>LINESTRING<br>(1354492<br>6232933...)</td><td></td><td></td><td></td></tr></tbody></table>

## Experimental Design, Materials and Methods

Data collection for the database was carried out by specialized teams from ADERA and AXE-SIG companies. Data collection was carried out on foot, and included a blind person able to make a relevant diagnosis. Two types of primitive data were collected:

* travel patterns, the source of the pedestrian graph supporting the travel system

* accessibility-specific qualifications: obstacles to the path, technical elements of road crossings, staircases, reserved parking spaces, etc.

The collection teams were equipped with digital and manual equipment: GPS antenna, camera, electronic level, laser meter and, above all, tablet. GIS work was organized around the open-source tools QGIS and Qfield Nomad module. The data collected was then consolidated in the office and delivered to the customer (local government) in the agreed formats. The latter then carried out quality checks and integrated the data into its GIS. Updates are scheduled every two years.

## Limitations

### Missing data

The original data was collected before the Accessibility standard was written, so some items are missing. Table 9 compares the object name as in the standard's conceptual data model, the layer name extracted from the QGIS template, its presence in the delivered dataset and the layer name in the dataset.
<table><caption>Table 9: Comparison between of the standard and the provided dataset</caption><thead><tr><th>Object name</th><th>Name in template</th><th>Presence</th><th>Layer name</th></tr></thead><tbody><tr><td>ASCENSEUR</td><td>ascenseur</td><td>No</td><td></td></tr><tr><td>CHEMINEMENT</td><td>cheminements</td><td>No</td><td></td></tr><tr><td>CHEMINEMENT_ERP</td><td>cheminement_erp</td><td>No</td><td></td></tr><tr><td>CIRCULATION</td><td>circulation</td><td>No</td><td></td></tr><tr><td>ELEVATEUR</td><td>elevateur</td><td>No</td><td></td></tr><tr><td>ENTREE</td><td>entree</td><td>No</td><td></td></tr><tr><td>ERP</td><td>ERP</td><td>No</td><td></td></tr><tr><td>ESCALATOR</td><td>escalator</td><td>No</td><td></td></tr><tr><td>ESCALIER</td><td>escalier</td><td>Yes</td><td>escalier</td></tr><tr><td>NOEUD</td><td>noeuds</td><td>Yes</td><td>noeud_cheminement</td></tr><tr><td>OBSTACLE</td><td>obstacles</td><td>Yes</td><td>obstacle</td></tr><tr><td>PASSAGE SELECTIF</td><td>passage_selectif</td><td>No</td><td></td></tr><tr><td>QUAI</td><td>quai</td><td>No</td><td></td></tr><tr><td>RAMPE</td><td>rampe</td><td>No</td><td></td></tr><tr><td>STATIONNEMENT_PMR</td><td>stationnement_pmr</td><td>Yes</td><td>stationnement_pmr</td></tr><tr><td>TAPIS ROULANT</td><td>tapis_roulant</td><td>No</td><td></td></tr><tr><td>TRAVERSEE</td><td>traversee</td><td>Yes</td><td>traversee</td></tr><tr><td>TRONCON_CHEMINEMENT</td><td>troncons</td><td>Yes</td><td>troncon_cheminement</td></tr></tbody></table>

We can see that not all the objects defined by the standard were delivered in the dataset.

There are a few differences between the conceptual data model and the object class name (notably the absence of underscores between two words), but also in the QGIS template that accompanies the standard (nodes and obstacles in the plural, troncon_cheminement becomes troncons). The names of layers supplied by Nantes Métropole follow the object name in lower case.

## General standard versus specific use cases

The Accessibility standard aims to provide “essential data to ensure a non-blocking path for people with disabilities or reduced mobility” [6, p. 8]. But mobility behaviors vary greatly from one individual to another, even if they have the same disability. For example, a visually impaired person, depending on whether he or she uses a cane or a guide dog, may walk along buildings, follow the kerbs or stand in the middle of the path.

The Accessibility standard, by construction, considers the path centered on the roadway and will only take into account obstacles on this path. Other obstacles (advertising hoardings, bicycle
parkings, letterboxes) placed on the edge of the path will not be taken into account if the width
of the path is sufficient.

Spatial coverage

The Accessibility standard specifies that local authorities with more than 10,000 inhabitants are obliged to survey the accessibility within a 200-meter radius of priority stops [6, p. 13].

Nantes Métropole has chosen to go beyond the regulatory obligation and make this census 300 meters around priority stops. And yet, even in a small area such as the Ile de Nantes, not everything is covered. Some streets have not been inventoried and a large area, which will be home to the future university hospital, has not been covered. As our project was based on a pedestrian mobility graph, these shortcomings severely limited the possibilities, and some elements were even disconnected from the main network due to their remoteness. In real-life use, this assumes that the user uses the public transport network to get from one priority stop to another in order to reach his or her destination. Depending on the situation, the algorithm may not be able to find a possible solution due to discontinuities, or due to the need for long detours.

Data accuracy

Given that the dataset was generated from data collected several years previously, semantic ac-
curacy (accuracy of object type surveyed) and presence/absence were not checked. Nor was the
geometric accuracy (accuracy of geographic coordinates of surveyed objects) analyzed. We were
able to make do with the raw data as there was no *in situ* experimentation, but when using this
type of data in a real-life situation,the dataset will have to demonstrate exemplary quality control.
This will have to be done in future studies.

Acknowledgements

The authors would like to thank Nantes Métropole for making the data available and for the dis-
cussions we were able to have.

We would also like to thank the authors of R language [7] and the R packages DataExplorer [8], here [9], mapsf [10], sf [11], skimr [12], targets [13], tidyverse [14] and xfun [15], which were used extensively in the preparation of this article.

Finally, we would like to thank the OpenStreetMap community [16], and in particular the Panora-
max project [17] from which the images illustrating the objects presented are taken, and more
particularly their respective authors (Carto’Cité and Koreller).

Data Availability

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