Bridges

Going through ALPR data, I noticed how some ALPR cameras were not positioned in typical areas or near the intersection of roads. Rather, these were installed at the intersection of roads and rivers. These bridges represent chokepoints in the road network that are unavoidable. For example, South of the Ohio river there are only 18 crossings (excluding ferries) along the Mississippi river wikipedia page. That is an area of ~800km / ~500miles. Thus, to observe all interstate traffic would use a trivial number of cameras. The same vulnerability exists on smaller rivers as well.
There is also the aspect that rivers tend to delineate the municipal boundaries. Municipalities/states will tend to place ALPRs around their perimeter. Although not a deliberate effort to monitor these “chokepoints”, the end result is the same.

Example:

Most of the ALPRs in the example above are on one side of the river. Thus, the county on the left is likely putting ALPRs all around the perimeter of the county.

What are Typical areas? (with overpass turbo queries):
In vicinity of ramps of large roads
nwr[highway=primary_link]({{bbox}});
nwr[highway=secondary_link]({{bbox}});
nwr[highway=motorway_link]({{bbox}});

Hospitals
nwr[amenity=hospital]({{bbox}});
nwr[healthcare=hospital]({{bbox}});

Parks
nwr[leisure=park]({{bbox}});

Shopping Malls
nwr[shop=mall]({{bbox}});

Sports Pitch
nwr[leisure=pitch]({{bbox}});

Warehouses
Police Departments / Correctional Facility
Lowes/Home Depot
Higher density housing (HOA areas/new builds)

The following ALPRs were detected within 100 meters of a bridge that crossed over a river.

Code

import pandas as pd
import geopandas as gpd
import folium
import itables
from datetime import datetime
from folium.plugins import MarkerCluster

m = folium.Map([35, -100], zoom_start=4)

bridgegdf = gpd.read_file("../../../osmetc/bridges.gpkg")
bridgegdf = bridgegdf.drop(["man_made", "river_waterway"], axis=1).rename({"alpr_osmid":"ALPR ID","alpr_highway":"ALPR highway","camdir":"Direction 1","camdir2":"Direction 2","road_osmid":"Road ID","road_name":"Road Name","road_highway":"Road Type","river_osmid":"River ID","river_name":"River Name"}, axis=1)

marker_cluster = MarkerCluster(disableClusteringAtZoom=10).add_to(m)

for idx, row in bridgegdf.iterrows():
    popup_html = f"<style> th\
                {{border:1px solid black;\}}</style>\
                <table><tr>\
                    <th>Road: </th>\
                    <th>{row['Road Name']}</th>\
                </tr><tr>\
                    <th>Road Type: </th>\
                    <th>{row['Road Type']}</th>\
                </tr><tr>\
                    <th>ALPR ID: </th>\
                    <th>{row['ALPR ID']}</th>\
                </tr><tr>\
                    <th>Road ID: </th>\
                    <th>{row['Road ID']}</th>\
                </tr><tr>\
                    <th>River ID: </th>\
                    <th>{row['River ID']}</th>\
                </tr><tr>\
                    <th text-align='center' colspan='2'><a href='https://www.openstreetmap.org/node/{row['ALPR ID']}' target='_blank'>https://www.openstreetmap.org/node/{row['ALPR ID']}</a></th>\
                </tr></table>"
    folium.Circle(
        location=[row.geometry.y, row.geometry.x], 
        popup=popup_html, fill=True, radius=20, weight=9,color="#9E2F02",opacity=0.8,fillOpacity=0.5
    ).add_to(marker_cluster)

m

<string>:17: SyntaxWarning: "\}" is an invalid escape sequence. Such sequences will not work in the future. Did you mean "\\}"? A raw string is also an option.
<>:17: SyntaxWarning: "\}" is an invalid escape sequence. Such sequences will not work in the future. Did you mean "\\}"? A raw string is also an option.
<string>:17: SyntaxWarning: "\}" is an invalid escape sequence. Such sequences will not work in the future. Did you mean "\\}"? A raw string is also an option.
<>:17: SyntaxWarning: "\}" is an invalid escape sequence. Such sequences will not work in the future. Did you mean "\\}"? A raw string is also an option.
/tmp/ipykernel_438935/1471398686.py:17: SyntaxWarning: "\}" is an invalid escape sequence. Such sequences will not work in the future. Did you mean "\\}"? A raw string is also an option.
  {{border:1px solid black;\}}</style>\
<string>:17: SyntaxWarning: "\}" is an invalid escape sequence. Such sequences will not work in the future. Did you mean "\\}"? A raw string is also an option.

Make this Notebook Trusted to load map: File -> Trust Notebook

Code

itables.show(pd.DataFrame(bridgegdf.drop(["geometry"], axis=1)), maxBytes=200000, allow_html=True)

^ⓘALPR ID	ALPR highway	Direction 1	Direction 2	Road ID	Road Name	Road Type	River ID	River Name	url
13461160002	NaN	175	NaN	107666714	11th Street	primary	766536158	Kishwaukee River	https://www.openstreetmap.org/node/107666714
12463240809	NaN	0	NaN	203503870	120th Avenue	primary	135591280	Macatawa River	https://www.openstreetmap.org/node/203503870
12474351315	NaN	160	NaN	203503870	120th Avenue	primary	135591280	Macatawa River	https://www.openstreetmap.org/node/203503870
13695559201	NaN	37	NaN	136354516	12600 South	primary	1422835174	Jordan River	https://www.openstreetmap.org/node/136354516
13672847501	NaN	265	NaN	5634625	126th Street	primary	319533454	Hudson River	https://www.openstreetmap.org/node/5634625
12639395803	NaN	145	NaN	127775221	12th Avenue	secondary	1494843949	Rock River	https://www.openstreetmap.org/node/127775221
13479789302	NaN	0	NaN	9452482	13th Street	primary	585253806	Savannah River	https://www.openstreetmap.org/node/9452482
13346618901	NaN	99	NaN	71070656	15th Avenue	secondary	1500117248	Rock River	https://www.openstreetmap.org/node/71070656
13346618201	NaN	270	NaN	71070656	15th Avenue	secondary	1500117248	Rock River	https://www.openstreetmap.org/node/71070656
13346617901	NaN	102	NaN	71070656	15th Avenue	secondary	1500117248	Rock River	https://www.openstreetmap.org/node/71070656
(1,565 more rows not shown)

Road name is missing?

Some bridges lack the “name” tag that is available in other bridges/roads. However, YOU can help correct the OpenStreetMap data by copying over the tag from the other segments of the road.