diff --git a/README.md b/README.md
index 065aae4..fca93b1 100644
--- a/README.md
+++ b/README.md
@@ -60,7 +60,8 @@ podman compose run --rm importer /app/scripts/03_import_pois.sh
 podman compose run --rm importer /app/scripts/04_import_geocoding.sh
 
 # Step 5: Preprocess OSRM routing graphs — run on the HOST, not in the container
-# (OSRM tools only exist inside the osrm/osrm-backend image)
+# Builds a local ARM64 OSRM image on first run (~30-60 min), then preprocesses
+# car/foot/bicycle profiles. Subsequent runs skip the image build.
 bash backend/scripts/05_import_routing_host.sh ~/dev/maps/data
 
 # Step 6: Register offline regions in the database
@@ -145,6 +146,8 @@ podman compose up -d postgres
 
 **Exec format error on Pi** — The postgres image is built locally from `postgis.Dockerfile` using `arm64v8/postgres` as base. Run `podman compose build postgres` to rebuild it.
 
+**OSRM exec format error** — `osrm/osrm-backend` is amd64-only. The project uses `osrm-arm64.Dockerfile` to build a native ARM64 image. Run `podman compose build osrm-driving` (builds once, shared by all three OSRM services) or let `05_import_routing_host.sh` build it automatically.
+
 ---
 
 ## Attribution
diff --git a/backend/docker-compose.yml b/backend/docker-compose.yml
index f4536e7..842fbcf 100644
--- a/backend/docker-compose.yml
+++ b/backend/docker-compose.yml
@@ -72,25 +72,40 @@ services:
       - "2322:2322"
 
   osrm-driving:
-    image: docker.io/osrm/osrm-backend:latest
+    build:
+      context: .
+      dockerfile: osrm-arm64.Dockerfile
     networks:
       - maps-net
     ports:
       - "5000:5000"
+    volumes:
+      - ../data/osrm/car:/data
+    command: osrm-routed --algorithm mld /data/region.osrm
 
   osrm-walking:
-    image: docker.io/osrm/osrm-backend:latest
+    build:
+      context: .
+      dockerfile: osrm-arm64.Dockerfile
     networks:
       - maps-net
     ports:
       - "5001:5000"
+    volumes:
+      - ../data/osrm/foot:/data
+    command: osrm-routed --algorithm mld /data/region.osrm
 
   osrm-cycling:
-    image: docker.io/osrm/osrm-backend:latest
+    build:
+      context: .
+      dockerfile: osrm-arm64.Dockerfile
     networks:
       - maps-net
     ports:
       - "5002:5000"
+    volumes:
+      - ../data/osrm/bicycle:/data
+    command: osrm-routed --algorithm mld /data/region.osrm
 
   importer:
     build:
diff --git a/backend/osrm-arm64.Dockerfile b/backend/osrm-arm64.Dockerfile
new file mode 100644
index 0000000..5ed8065
--- /dev/null
+++ b/backend/osrm-arm64.Dockerfile
@@ -0,0 +1,41 @@
+FROM docker.io/arm64v8/debian:bookworm AS builder
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    build-essential cmake git pkg-config \
+    libboost-all-dev libtbb-dev liblua5.4-dev \
+    libxml2-dev libzip-dev libbz2-dev \
+    && rm -rf /var/lib/apt/lists/*
+
+ARG OSRM_VERSION=v5.27.1
+RUN git clone --depth=1 --branch ${OSRM_VERSION} \
+    https://github.com/Project-OSRM/osrm-backend.git /osrm
+
+RUN cd /osrm && mkdir build && cd build && \
+    cmake .. -DCMAKE_BUILD_TYPE=Release && \
+    make -j$(nproc) osrm-extract osrm-partition osrm-customize osrm-routed && \
+    make install
+
+# ---- runtime ----
+FROM docker.io/arm64v8/debian:bookworm-slim
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    libboost-filesystem1.81.0 \
+    libboost-iostreams1.81.0 \
+    libboost-regex1.81.0 \
+    libboost-date-time1.81.0 \
+    libboost-thread1.81.0 \
+    libboost-program-options1.81.0 \
+    libtbb12 liblua5.4-0 libxml2 libzip4 libbz2-1.0 \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY --from=builder /usr/local/bin/osrm-extract \
+                    /usr/local/bin/osrm-partition \
+                    /usr/local/bin/osrm-customize \
+                    /usr/local/bin/osrm-routed \
+                    /usr/local/bin/
+
+# Lua profiles (car.lua, foot.lua, bicycle.lua, etc.)
+COPY --from=builder /osrm/profiles/ /opt/
+
+WORKDIR /data
+EXPOSE 5000
diff --git a/backend/scripts/05_import_routing_host.sh b/backend/scripts/05_import_routing_host.sh
index a1e0dcb..3c72025 100755
--- a/backend/scripts/05_import_routing_host.sh
+++ b/backend/scripts/05_import_routing_host.sh
@@ -1,13 +1,17 @@
 #!/bin/bash
 # scripts/05_import_routing_host.sh
 # Run this directly on the Pi host (not inside the importer container).
-# OSRM tools only exist inside the osrm/osrm-backend image.
+# Builds a local ARM64 OSRM image if it doesn't exist, then preprocesses
+# routing graphs for car, foot, and bicycle profiles.
 
 set -euo pipefail
 
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+BACKEND_DIR="$(dirname "$SCRIPT_DIR")"
 DATA_DIR="${1:-$HOME/dev/maps/data}"
 OSRM_DIR="${DATA_DIR}/osrm"
 PBF_FILE="${DATA_DIR}/osm/region.osm.pbf"
+OSRM_IMAGE="maps-osrm-arm64:latest"
 
 if [ ! -f "$PBF_FILE" ]; then
     echo "ERROR: PBF file not found at $PBF_FILE"
@@ -15,6 +19,15 @@ if [ ! -f "$PBF_FILE" ]; then
     exit 1
 fi
 
+# Build the ARM64 OSRM image if not already present
+if ! podman image exists "$OSRM_IMAGE"; then
+    echo "=== Building ARM64 OSRM image (one-time, ~30-60 min on Pi) ==="
+    podman build \
+        -f "${BACKEND_DIR}/osrm-arm64.Dockerfile" \
+        -t "$OSRM_IMAGE" \
+        "$BACKEND_DIR"
+fi
+
 for PROFILE in car foot bicycle; do
     PROFILE_DIR="${OSRM_DIR}/${PROFILE}"
     mkdir -p "$PROFILE_DIR"
@@ -24,17 +37,17 @@ for PROFILE in car foot bicycle; do
 
     podman run --rm \
         -v "${PROFILE_DIR}:/data" \
-        docker.io/osrm/osrm-backend:latest \
+        "$OSRM_IMAGE" \
         osrm-extract -p "/opt/${PROFILE}.lua" /data/region.osm.pbf
 
     podman run --rm \
         -v "${PROFILE_DIR}:/data" \
-        docker.io/osrm/osrm-backend:latest \
+        "$OSRM_IMAGE" \
         osrm-partition /data/region.osrm
 
     podman run --rm \
         -v "${PROFILE_DIR}:/data" \
-        docker.io/osrm/osrm-backend:latest \
+        "$OSRM_IMAGE" \
         osrm-customize /data/region.osrm
 
     echo "OSRM $PROFILE profile ready."