Route finder: how it works and how to use it

At a glance

Examples computed in November 2026 with the default settings; central estimates.

How a route is found

The map is divided into a grid of cells, and every cell is given a price: what one kilometre of this line would cost if it ran through that cell. The route finder then looks for the path through the grid with the lowest total cost. A step between neighbouring cells, including diagonally, costs the average price of the two cells times the distance.

1. Price every cellLine, terrain, land cover, sensitive areas, ground, land, access, water, crossings
2. Remove no-go areasProtected land, military land, airports, ground too steep to build on
3. Search from both endsThe cheapest route and its cost corridor
4. Find alternativesRoutes forced onto new ground
5. Search again at 100 mOver the corridor (contiguous US, GB, Europe)
6. Price each itemLow, central and high

Searching from both ends

For a line between two points, the search spreads out from both ends at once — a full least-cost search (Dijkstra's algorithm) from A and another from B — and the best route is where they meet. Adding the two searches together also gives, for every cell, the cheapest route forced through it. That is what draws the cost corridor: the ground a line could use for at most 5%, 10% or 20% more than the best route. The animation you see when results arrive is these searches spreading out, with the paths they followed.

Alternatives

Ask for more than one route and the finder makes the ground near each route already found more expensive, then searches again. A new route is kept only if at least 40% of it runs over new ground. You get the best route and up to nine alternatives, each with its own cost. If fewer come back than you asked for, the result says why: no other way differs enough, or every other way would cross more than 50 km of water by AC cable.

Long lines

For long lines the finder first searches a coarser version of the grid to find the broad corridor, then searches the detailed grid inside it. On six lines short enough for one full 100 m search as well, the answer searched along the line came within about 1.1% of that search's price, above it on some and below it on others. The longest lines have no full search to compare with.

100 m routes in the contiguous United States, Great Britain and Europe

Here the search runs in two passes. A 1 km pass over the whole area finds the best route and its cost corridor. The best route is then searched again on a 100 m grid, over as much of the corridor as the search can hold. On most lines that is one search from both ends, over all the ground a line could use for up to 10% more than the best route, and it usually takes a few seconds. A line too long for that search, or one that crosses water, is searched along its length instead, a stretch at a time, in a band up to 20 km either side of the 1 km route, which can take a minute or more. You see this as the second stage of the animation, “Refining at 100 m”. Alternatives are searched again at 100 m within about 3 km either side of them.

The 100 m pass uses 100 m slope (from the Copernicus 90 m elevation model), 100 m land cover, 100 m protected and sensitive areas, and the roads, railways, waterways and lines a route would cross — so the route follows real boundaries and terrain and avoids needless crossings. The line cost, the local price level, ground conditions and land values change slowly across the map and are taken from the 1 km cell around each 100 m cell. In the contiguous United States, Great Britain and Europe a route's land is at 100 m, however long the line. Water stays at 1 km, because the 100 m data covers land, and the result says so; on the 2 km and 5 km grids a route stays at that grid's resolution.

Stops along the way

A line between two points can pass through up to eight stops, in the order you give them. The finder routes each section between consecutive points, then puts the sections' own options together into whole routes, cheapest first. Each stop is one of:

• a pass-through point — the line simply passes through it, at no extra cost;
• a substation (AC lines) — a new substation on the line at that point, at the published cost for the voltage and region, the local price level and the local labour factor (on the 1 km and 100 m grids of the contiguous United States the labour factor alone, with no price level; on a section searched on the 2 km or 5 km grids the price level alone);
• a converter station (HVDC) — an extra converter at the link's rating, making a multi-terminal link: the ends and every converter stop each pay for one converter.

The result shows each section's length and cost as well as the whole route's. For an HVDC overhead line, the underground options are shown for the whole route as well.

Site to grid

From a site, the finder works out the voltage a project of your size would usually connect at, finds every substation and line at that voltage within 60 km (then 150 km), and searches outward from the site to all of them at once. It adds the cost of connecting — a bay at an existing substation, or a new substation on a line — and returns the cheapest options, each to a different connection point.

What a kilometre costs

Each cell's price per kilometre is built from the items below. Every item has a low, central and high value, and a route's range is the sum of its items.

Outside the contiguous United States, Great Britain and Europe, the easement and ground-condition items and the local labour factor are not included, because there is no consistent land-value, ground or local wage data. The result says so. The access tracks and the rise in the slope multiplier above 10° are not included there either, because those grids hold no distance to the nearest road and keep the plain slope classes.

The grid connection on the Site Development Cost map uses the same line costs, terrain and land-cover multipliers, sensitive-area costs and ground conditions and, since November 2026, in the contiguous United States, Great Britain and Europe, the steepness above 10° and the access tracks. The main differences: it has no easement, because that map prices the site's land separately; it has no allowance for significant crossings; it searches on the 1 km grid, with no 100 m search; and it prices the whole route at the site's local price level and labour factor, not each cell's. On protected land, military land and airports, which this route finder does not go through by default, on open water, which it crosses by cable by default, and on ground too steep to build on, which it does not cross, that map charges 10 times the line's cost per km instead: a heavy penalty rather than a block, so a connection goes round such ground when that is cheaper. A site on or behind too-steep ground keeps a figure, and that figure does not say the ground can be built on; on that map's click, and on the Grid Connection by Size and Site Value clicks, a site on such ground is told so. A site inside a no-go area, or with no grid of the connection voltage reachable over land, has no figure. A click at the edge of such a cell can still show a figure, read from the cells around it, and the card says so.

Obstacles and exclusions

Everything on the map falls into one of three treatments. No-go areas are removed from the search: on the 1 km and 100 m searches a route never enters them and goes round, however far (the 2 km and 5 km grids can cross a strip narrower than a cell and, where that is the only way through, an airport, and the answer then says so: see Coverage and resolution). Priced areas can be crossed but cost more, so a route goes round them when that is cheaper and through them when it is not. Weighted conditions raise the price of a kilometre without ever blocking it.

Narrow necks of land. On the 1 km first pass a cell that a no-go area touches is no-go whole: protected land, military land, an airport's outline or the square round its point. A cell too steep at 1 km is closed the same way. That can close a neck of land that is open on the ground. When the first pass finds no way out for a point, it checks at 100 m which of those cells the point's ground really reaches, and only the first pass may step through them. The final 100 m route goes round every no-go area by its true outline, or the line is refused. Those cells never count in a route's price, its corridor or the search picture. An answer found that way carries no note: the route goes round the outlines.

A click on an airport. When a site or an end of a line stands on an airport and the search cannot leave it, the answer says that the point is on an airport, names it where it can, and says what to do: move the point off the airport, or untick Airports. The same goes for protected land and military land. A point on an airport with clear ground beside it can still answer; if no route is found from it, the refusal keeps its own advice, on water crossings too, and adds that the point is on an airport. The other refusals keep their own words: a point on clear ground is told that no connection or no route was found.

Line types and water

Water can be crossed only where it is no deeper than the limit you choose — from 50 m to 1,000 m, with 200 m (roughly the continental shelf) as the default. Depths come from NOAA's ETOPO 2022 model; a lake's depth is measured from its own surface. Each landfall, where an overhead line meets its cable, adds the cost of a substation bay at the local price level and the local labour factor (on the 1 km and 100 m grids of the contiguous United States the labour factor alone, with no price level; on the 2 km or 5 km grids the price level alone), and the search weighs the cable and the landfalls against the way round on land. It makes that choice at 1 km, and the final price is worked out at 100 m, so the two can differ: a line with water allowed can come out dearer than the same line with it not allowed. To compare, run the line again with the box unticked.

An AC crossing is kept within 50 km because an AC cable's charging current limits how far it can run. If the cheapest route would need a longer AC crossing, the finder looks for another way round; if there is none, it says so and suggests HVDC. Each alternative route is held to the same limit.

Why an AC cable costs more in the contiguous United States. There the finder prices an AC submarine cable at four times ACER's European figure: about $11m per km, with a range of about $7m to $13m. ACER publishes one price across voltages, and its sample looks mostly lower-voltage. We found no public per-km price for a 345 kV AC submarine cable in the United States, so this is an estimate, and what it rests on is not like for like. Two US 138 kV projects, both replacements: $105m for two circuits across about 4 miles at the Straits of Mackinac in 2021, taking out the old cables too, and $140m for about 11 miles under Long Island Sound in 2008. Against those, a contract of about €68m in 2021 for the cable alone, 37 km at 132 kV, from Elba to the Italian mainland. New England's planners put an underground line at more than four times a new overhead line, the same gap ACER's figures show in Europe between its cable and its overhead line. The factor prices one circuit: a crossing that must carry as much as a large overhead line would need more, and at the lowest voltages it may read high. Great Britain, Europe and the 2 km and 5 km grids keep ACER's price, and the HVDC cable has its own price.

Why an HVDC cable costs more in the contiguous United States. There the finder prices an HVDC cable at 2.6 times ACER's European figure: about $4.3m per km at sea for a link of up to 1,400 MW, with a range of about $3.2m to $4.9m, and twice that on land, where it is two cables. New England's grid operator, in its 2050 Transmission Study, puts an HVDC cable at $10.5M per mile in 2023 dollars, a figure from the National Renewable Energy Laboratory with a 50 % contingency added; without the contingency that is about $4.3m per km. The finder adds no contingency to any other line, so it leaves this one out too, and it does not bring the 2023 dollars forward, so it may read a little low. The study does not say how large a link its cable carries; the offshore links it looks at are 1,200 MW. This is an estimate. An HVDC overhead line's water crossings and underground sections use the same cable price, and so does an HVDC link sent to Scenario Studio. Great Britain, Europe and the 2 km and 5 km grids keep ACER's price.

HVDC overhead lines: overhead, underground, or both

For an HVDC overhead line between two points, the route finder shows the options side by side, each labelled and sorted by cost:

• Overhead — the overhead route, and its alternatives.
• Underground HVDC cable — the cable buried the whole way.
• With underground sections — the overhead line going underground wherever a buried cable is cheaper or the only way through, when that differs from both of the above.

Underground sections may pass under airports, and under protected land priced as a cable in a sensitive area (1.25 times); they never cross strict wilderness or military land. Each change between overhead line and cable adds a substation bay. If no overhead route exists at all — for example, from a town inside a national park — the line goes underground where it must, and the result says so. On the 1 km grid a route with underground sections stays at 1 km for now, with no 100 m pass; on the 2 km and 5 km grids it stays at that grid's resolution. A very long line shows the options beside the overhead route only if the time allowed for the search lets them finish, and the result says when it does not.

Coverage and resolution

There is no fixed length limit. With both ends in the contiguous United States, or both in Great Britain, Northern Ireland and Europe, a line's land is routed at 100 m however long it is: a coarse search finds the way, a 1 km search the corridor, and the 100 m search runs along it. A long line, or one that crosses water, can take a minute or more, and shows at most three routes; a long line's corridor is shaded on 4 km blocks. Any other line takes the finest grid that holds both ends: 2 km, or the 5 km world grid for a line between continents or one too long for the 2 km grids. The result always states the resolution it used and, when it moved to a coarser grid, why. A line crossing the Pacific's date line cannot be routed.

What falls back, and says so. If the 100 m search runs out of the time allowed, a long line is answered from the 2 km or 5 km grid, and a shorter one crossing water stays at 1 km, each with a note on its result and on its print. The 2 km and 5 km grids' price table reads lower than the 100 m table on long lines, so a price from that fallback is not comparable with a 100 m answer, and trying again may give the 100 m answer. Such a price is marked provisional wherever it can be read: the saved route, the CSV, the GeoJSON, the KML and what goes to Scenario Studio. If no 100 m way exists on one part of a line, that part is drawn and priced at 1 km and not confirmed at 100 m, and a note says where and why. A part that would run through a cell the 1 km map closes, other than the cell an end of the line stands in, never stays at 1 km: the line keeps the 1 km answer its first search gave, or is refused if it had none. A search that covered the whole area round a line and found no way stands: no coarser grid overturns it, and where the AC crossing limit was the reason the answer says to try an HVDC line type. A line too long for that search, or whose search area could not widen as far as it asks, goes on to the 2 km or 5 km grid, with a note, when the ground at an end is too large to check at 100 m, or when the line may cross water by AC cable, and is refused if that grid finds no way either. Any other line with an end shut in on smaller ground is refused at once.

Why long lines cost more than they used to. A kilometre now costs the same however long the line. Long lines in the contiguous United States and Europe used to run on the 2 km and 5 km grids, on the international default price; they now run at 100 m on the same regional table as every shorter line. Their published prices rise: a 345 kV line from Dallas to New York, which the 2 km grid priced at its nearest class, 400 kV, goes from about $4.0bn to about $7.3bn, and it is also a shorter route. On other continents the international default stays, as there is no regional table.

A route answered from the 2 km or 5 km grid carries a note on its result and on its print: the line was searched at that resolution, so it can cross no-go areas narrower than a grid cell, which the 1 km and 100 m searches go round; and its line price uses the European cost table times a national level, which can differ widely from the finer grids' price. A 1 km or 100 m answer carries no such note.

On the 2 km and 5 km grids a line can cross an airport where that is the only way through. Those grids have no 100 m search. When the first search finds no way and Airports is ticked, it searches again with airport cells very expensive, so the line crosses as few as it can, and the answer says so on its result and on its print, naming the airport where it can, and saying the search was coarse. The result's Crosses row gives the distance. If that search finds no way either, the first refusal stands. With Airports unticked, or when the first search finds a way, none of this happens.

Accuracy and limits

The route finder is for screening. Use it to compare options, see where a line can and cannot go, and get an order-of-magnitude cost early, before a routing or feasibility study.

• Costs are unit-cost estimates from published sources, with the sources' own low and high values (for ACER, the 25th and 75th percentiles). The HVDC figures, the allowances for sensitive areas and crossings, and the rise in cost with steepness and its limits are screening assumptions.
• Not included: tower spotting, line-of-sight, landowner negotiation, crossing permits and agreements, and network or system studies. Crossings are an allowance, not a design.
• Data age: protected areas, land cover, transport and grid data are refreshed periodically; very recent designations, roads or substations may be missing.
• Outside the contiguous US and Europe: no easement or ground-condition costs, and protected areas, roads, railways and waterways come from OpenStreetMap, whose coverage varies by country. Alaska, Hawaii, Puerto Rico and the US Virgin Islands keep the US designations for protected areas (PAD-US). Alaska, Hawaii and Puerto Rico also keep the US sources for roads, railways and waterways, with OpenStreetMap's as well in Puerto Rico. Airports are no-go there too, from OpenStreetMap: its regional extracts and, in the United States (Alaska and Hawaii included), Puerto Rico and the US Virgin Islands, the airport points the Site Development Cost map reads, a 1.5 km disc round one with an IATA code and the grid cell it falls in for any other airfield (a point on a sea cell at this resolution takes the nearest land cell). The route finder also reads the outlines of the airports OpenStreetMap maps as areas, Honolulu, Juneau, Sitka and San Juan among them: the same disc or cell, and every land cell the airport's outline touches. On the 5 km grid, where a cell is 25 km², those points and outlines count only for an airport with an IATA code, in the United States and Europe, with Kosovo, the Isle of Man, the Channel Islands, Åland, the Faroes, northern Cyprus and Melilla; elsewhere that grid reads the regional extracts alone, which miss many small coded airstrips. That grid's Europe also takes in France's overseas land, Guadeloupe, Martinique, French Guiana, Réunion and Mayotte, and the Netherlands' Bonaire, as its country table holds them as France and the Netherlands. Great Britain and Europe read the same points and outlines on the 5 km grid, and on the 2 km grids where they reach southern and eastern Europe. The Site Development Cost map reads them too, in Alaska, Hawaii and Puerto Rico. Guam, the Northern Marianas and the Aleutians west of 180° on their 2 km grids read the regional extracts alone.

Finding a route

The route finder is in the sidebar under Markets, Economics & Analysis › Studies › Route finder, on desktop, for Desk subscriptions and above.

1. Choose a mode. Site → grid to connect a project, or Line between two points for a link.
2. Choose the line type. AC overhead (the default), HVDC overhead or HVDC cable. For HVDC between two points, set the link rating in MW (2,000 by default). For an HVDC overhead line, Show a route with underground sections is ticked by default; untick it to see the overhead route only (it still goes underground if there is no other way).
3. Set how many routes you want, from 1 to 10.
4. Water. For overhead lines, Cross sea and lakes by cable is ticked by default; untick it to make the line go round. Set the deepest water a cable may cross.
5. Pick your points. For a site, click Pick site, click the map and enter the project size in MW. For a line, pick A and B and choose the voltage.
6. Add stops (optional). For a line, click Add stop and click the map, once for each stop (up to eight); the line passes through them in order from A to B. For each stop choose what it is — a pass-through point, or a station (a substation on an AC line, a converter station on an HVDC line). Use ↑ to move a stop earlier and × to remove it.
7. Check the no-go and sensitive options. Every no-go layer is avoided by default. Untick any you want a route allowed to cross, or switch off sensitive-area pricing.
8. Click Find routes. The search plays out on the map — in the contiguous United States, Great Britain and Europe in two stages, the 1 km search and then the 100 m search over the corridor — then the routes draw themselves and the result opens.

Reading the results

On the map

• The best route is solid orange; alternatives are dashed in their own colours. For an HVDC overhead line, each route is labelled overhead, underground HVDC cable or with underground sections.
• The corridor is shaded in three bands: a line anywhere in the deepest band costs at most 5% more than the best route, the middle 10% and the palest 20%. Click a band for the figure.
• Red outlines are no-go areas the route went round (on the 2 km and 5 km grids, a part narrower than a grid cell can still be crossed); amber are designated areas it crosses. Click either for its name and designation.
• Stops are marked on the map: a station filled in purple, a pass-through point as a hollow circle.
• Hover anywhere in the shaded search area to see what a kilometre of this line would cost there and why: the line, the terrain and land-cover multiplier, the sensitive-area premium, ground conditions, easement and any access track — or the cable and the water depth at sea. Ground too steep to build on says so.

The result

Every route lists its length (and the straight-line distance), its total with a low–high range, and each cost item; with stops, each section's length and cost too. Click a route for what it goes over — named designations with their km, ground conditions, km by terrain difficulty, and the motorways, railways, waterways and power lines it crosses — and what it goes round: the named no-go areas within 10 km and how far away it passes.

Taking it further

• Save a result to your subscription's workspace, then open, print or delete it from the Saved tab.
• Print / PDF makes a one-page report with the map, the key, every route's costs and the sources.
• Download CSV (every cost item), GeoJSON (routes, corridor and points) or KML for Google Earth. The CSV and GeoJSON say which search a route came from (its resolution and grid, the data release and, where stated, the dollar year); the KML carries the coarser grids' note when it applies.
• Send to Scenario Studio to add the route to a power-system scenario — an AC route as a new line, an HVDC route as an HVDC link carrying the route's own costs — or Use in Connection Study to open the study at the route's start with the route drawn: the result shows the routed km and the route's indicative total (line, terrain, connection and the route's other items) beside the study's own price, which stays on the straight-line distance. A route with substations or converter stations at its stops goes as one line per section, from station to station (a pass-through stop stays a bend within its section); for HVDC, each converter at a stop is shared between the two sections either side, so the sections add up to the route's cost. Only an HVDC route on the contiguous US grid states a dollar year, and the Studio brings its price from that year to the run's. A route in Great Britain or Europe, a route on the 2 km or 5 km grids (its line and its stations can be in different years), or a route through stops whose sections do not share a year states none, and nor does a route saved before the year was kept, so the Studio asks you to type its cost in the run's money.

Data sources

Full attributions are on the licences page.