diff --git a/add-tag/Cargo.lock b/add-tag/Cargo.lock
new file mode 100644
index 0000000..456ee48
--- /dev/null
+++ b/add-tag/Cargo.lock
@@ -0,0 +1,133 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "add-tag"
+version = "0.1.0"
+dependencies = [
+ "rayon",
+]
+
+[[package]]
+name = "autocfg"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "crossbeam-channel"
+version = "0.5.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf2b3e8478797446514c91ef04bafcb59faba183e621ad488df88983cc14128c"
+dependencies = [
+ "cfg-if",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-deque"
+version = "0.8.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ce6fd6f855243022dcecf8702fef0c297d4338e226845fe067f6341ad9fa0cef"
+dependencies = [
+ "cfg-if",
+ "crossbeam-epoch",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-epoch"
+version = "0.9.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "46bd5f3f85273295a9d14aedfb86f6aadbff6d8f5295c4a9edb08e819dcf5695"
+dependencies = [
+ "autocfg",
+ "cfg-if",
+ "crossbeam-utils",
+ "memoffset",
+ "scopeguard",
+]
+
+[[package]]
+name = "crossbeam-utils"
+version = "0.8.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3c063cd8cc95f5c377ed0d4b49a4b21f632396ff690e8470c29b3359b346984b"
+dependencies = [
+ "cfg-if",
+]
+
+[[package]]
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+
+[[package]]
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+checksum = "ee512640fe35acbfb4bb779db6f0d80704c2cacfa2e39b601ef3e3f47d1ae4c7"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.139"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "201de327520df007757c1f0adce6e827fe8562fbc28bfd9c15571c66ca1f5f79"
+
+[[package]]
+name = "memoffset"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d61c719bcfbcf5d62b3a09efa6088de8c54bc0bfcd3ea7ae39fcc186108b8de1"
+dependencies = [
+ "autocfg",
+]
+
+[[package]]
+name = "num_cpus"
+version = "1.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0fac9e2da13b5eb447a6ce3d392f23a29d8694bff781bf03a16cd9ac8697593b"
+dependencies = [
+ "hermit-abi",
+ "libc",
+]
+
+[[package]]
+name = "rayon"
+version = "1.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1d2df5196e37bcc87abebc0053e20787d73847bb33134a69841207dd0a47f03b"
+dependencies = [
+ "either",
+ "rayon-core",
+]
+
+[[package]]
+name = "rayon-core"
+version = "1.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4b8f95bd6966f5c87776639160a66bd8ab9895d9d4ab01ddba9fc60661aebe8d"
+dependencies = [
+ "crossbeam-channel",
+ "crossbeam-deque",
+ "crossbeam-utils",
+ "num_cpus",
+]
+
+[[package]]
+name = "scopeguard"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
diff --git a/add-tag/Cargo.toml b/add-tag/Cargo.toml
new file mode 100644
index 0000000..d6ab931
--- /dev/null
+++ b/add-tag/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "add-tag"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+rayon = "*"
diff --git a/add-tag/src/main.rs b/add-tag/src/main.rs
new file mode 100644
index 0000000..1af8df3
--- /dev/null
+++ b/add-tag/src/main.rs
@@ -0,0 +1,63 @@
+use std::env;
+use std::fs;
+use std::fs::File;
+use std::collections::HashSet;
+use std::io::BufReader;
+use std::io::BufWriter;
+use std::io::prelude::*;
+
+use rayon::prelude::*;
+
+fn main() -> std::io::Result<()> {
+    let args: Vec<_> = env::args().collect();
+    let map_file_path = args[1].clone();
+    let cam_file_path = args[2].clone();
+    let out_file_path = args[3].clone();
+    println!("In file {}", map_file_path);
+
+    let camera_ids_content = fs::read_to_string(cam_file_path)
+        .expect("Should have been able to read the file");
+
+
+    let seen_from_camera_ids: HashSet<_> = camera_ids_content.lines().map(|l| format!("w{}", l)).collect();
+
+    println!("Loaded {} way ids seen from camera", seen_from_camera_ids.len());
+
+    let input = File::open(map_file_path)?;
+    let input = BufReader::new(input);
+
+    let output = File::create(out_file_path)?;
+    let mut output = BufWriter::new(output);
+
+    let mut line_iter = input.lines();
+
+    loop {
+        let mut batch = vec![];
+        for _ in 0..3_000_000 {
+            if let Some(line) = line_iter.next() {
+                batch.push(line?);
+            } else {
+                break;
+            }
+        }
+
+        if batch.is_empty() {
+            break;
+        }
+
+        let out_batch: String = batch.into_par_iter()
+            .map(|line| {
+                if line.starts_with('w') && seen_from_camera_ids.contains(line.split(' ').next().unwrap())  {
+                    line.replace(" T", " Tcamera=yes,")
+                } else {
+                    line
+                }
+            })
+            .reduce(String::new,
+                    |mut a, b| { a.push_str(&b); a.push('\n'); a });
+
+        output.write_all(out_batch.as_bytes())?;
+    }
+
+    Ok(())
+}