User Guide

How to use the Zero Emission HGV Infrastructure Planner. A quick-reference guide for exploring charging scenarios across Scotland.

Heriot-Watt University

Launch Tool

What is this tool?

The ScotVolt is an interactive dashboard for exploring what happens when Scotland's heavy goods vehicles (HGVs) switch from diesel to electric. It uses simulation output from the MILES agent-based model to show where chargers would be needed, how much electricity they would draw, and whether the local electricity grid can handle it.

This dashboard covers 56 scenario cells drawn from a full year of MILES simulation, spanning summer and winter operations for Scotland's HGV fleet. A small number of additional cells are pending and will be added when available.

Indicative results. Numbers are based on a full year of MILES output but assume the grid in its current state, without scheduled reinforcement. Refer to the Phase 2 Technical Report for the full methodology and caveats.

Data & Sources

The demand data behind this tool comes from MILES, an agent-based simulation developed at Heriot-Watt University that models individual HGV journeys across Scotland. MILES is driven by real-world telematics data covering approximately 80,000 truck journeys, shared by commercial fleet operators.

Is the sample large enough? The telematics sample represents around 2% of Scotland's registered HGVs but captures approximately 12% of Scottish HGV kilometres. Because a small number of vehicles account for a large share of the distance driven, a sample of this size is statistically representative of how the fleet actually uses the road network. In transport modelling, samples of this scale are considered robust for capturing real-world demand patterns, the goal is to represent the movement of goods, not to survey every individual vehicle.

Charger locations come from several sources, shown in the Assumptions tab:

Existing and planned sites from operators and programmes including ScotZEB, ZEHID, and First Bus (already operational or in construction).
Identified-need sites flagged by the modelling and analysis as locations where charging will be required (from the HWU/Strathclyde research and by-hand corridor analysis).

Each charger's source is shown in its popup, and the full breakdown of location sources and counts is listed in the Assumptions tab.

Scenarios

The dashboard contains 56 scenario cells, each representing one combination of the following parameters across one full simulated year:

Parameter	Values
Season	Summer, Winter
Charger network	All chargers, Core chargers only
Depot variant	With depot charging, Without depot charging
Battery capacity	500 kWh, 1000 kWh
Charger power	350 kW, 500 kW
Energy intensity	Varies by season (summer 1.0 to 1.7 kWh/km, winter 1.26 to 2.15 kWh/km)

Energy intensity varies by season because cabin heating, denser cold air and battery efficiency losses push consumption per kilometre up in winter. The dashboard's efficiency dropdown therefore shows different values depending on the season you pick.

Eight of the 64 possible combinations are not yet populated and will be added once MILES output is available.

The 4 Tabs

The toolbar at the top of the dashboard switches between four views:

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Routing

Explore the 6 key freight corridors across Scotland. See which charger stops a truck would need on each route, based on vehicle range and charger locations. You can also build custom routes between any two hubs.

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Charging

The main analysis view. Two side-by-side maps show how many vehicles visit each charger and how much energy they draw from the grid. Select a scenario using the sidebar, then click any circle for detail.

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Bay Sizing

How many physical charging bays does each location need? Uses Erlang B queuing theory (the same maths used for phone networks) applied to MILES visit data, targeting less than 5% chance of arriving to find all bays occupied.

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Assumptions

Full list of vehicle assumptions, charger sources, routing methodology, and scope limitations. Read this first if you want to understand what's behind the numbers.

Reading the Charging Maps

The Charging tab shows two maps side by side. They show the same charger locations but sized by different metrics.

Left: Utilisation (Vehicle Visits)

Large = many visits, small = few visits, orange = grid constrained.

Circle size = number of vehicle visits per day. Blue = grid can handle the load. Orange = insufficient grid headroom.

Right: Grid Impact (Total Energy)

Large = high MWh per day, small = low, bright = exceeds headroom.

Circle size = total energy consumed (MWh) per day. Blue = within grid headroom. Purple = exceeds available headroom.

Why two maps?

A charger can be busy (lots of quick top-ups from passing trucks) without drawing much total energy. Or it can have fewer visitors but high total energy draw (long, heavy charges). The left map tells you which sites are popular; the right map tells you which sites stress the grid. A site that looks fine on the left might be a problem on the right.

What do the legends show?

Each map has a legend in the bottom-left corner. It explains the circle size scale, the colour coding (feasible vs constrained), and confirms that all values represent one simulated day from the MILES agent-based model.

What the Popups Show

Click any circle on either map to see the detail popup. The fields are:

Field	What it means
Usage count	How many vehicles visited this charger in the simulated day.
Peak simultaneous	The maximum number of vehicles charging at the same time during the day.
Total charge (MWh)	Total electricity delivered to all vehicles at this site during the day.
Substation	The nearest electricity substation that would supply this charger. If blank, no substation has been mapped to this location.
Headroom (MW)	How much spare capacity the substation has after existing demand. Higher is better.
Feasible	Yes = the grid can handle the charging load. No = the charger demand exceeds available grid capacity.

No substation linked? Some charger locations haven't been matched to a substation in the analysis yet. This doesn't mean they're infeasible; it means the grid assessment hasn't been done for that site. These appear as "No substation linked" in the popup.

Comparing Scenarios

You can compare multiple scenarios using the Scenario Comparison panel in the Charging sidebar:

Choose your first scenario parameters (efficiency, battery, power, network, season) and click Load Scenario.
Click + Scenario in the Comparison section. This saves the current scenario's key metrics.
Change the parameters to a different scenario and click Load Scenario again. The maps update.
Click + Scenario again. A comparison table appears showing both scenarios side by side: charger count, total MWh, peak simultaneous, feasible %, infeasible sites, and average headroom.

Note: The maps always show the most recently loaded scenario. The comparison table stores summary metrics so you can see how scenarios differ without switching back and forth. Different scenarios may show slightly different charger counts because the MILES simulation routes vehicles to different charger subsets depending on parameters.

Frequently Asked Questions

Is this showing data for one day or one year?: One simulated year. The figures in the dashboard are annual totals from a full-year MILES run. The Charging tab also shows hourly profiles where available. A separate testing dashboard exists for one-day MILES samples.
Why do some large circles show very small numbers when I click them?: The two maps scale circles by different metrics. Left scales by visit count, right scales by total MWh. A charger with high average power but few visits could appear large on one map and small on the other.
Why is the substation field blank or showing "No substation linked"?: Not all charger locations have been mapped to their nearest substation yet. The substation analysis requires running a separate post-processing step that matches each charger to the closest substation in the SPEN/SSEN network data.
Why does my chosen efficiency disappear when I switch season?: Energy intensity is season-dependent. Summer uses 1.0 to 1.7 kWh/km, winter uses 1.26 to 2.15 kWh/km. When you change season, the efficiency dropdown updates to show only the values available for that season.
Why do some scenario combinations return "no data"?: Eight of the 64 possible cells are not yet populated in the dataset. If you pick one of these, the dashboard reports no data found. These will be added as MILES output becomes available.
What does "Feasible: Yes/No" actually mean?: "Feasible" means the nearest substation has enough spare capacity (headroom) to supply the charger's peak demand without exceeding the substation's rated capacity. "No" means a grid upgrade would likely be needed before installing chargers at that location. This is based on current grid data and does not account for planned reinforcement.
What's the difference between the Charging tab and Bay Sizing tab?: The Charging tab shows what happens: how many vehicles visit, how much energy they use, and whether the grid can cope. The Bay Sizing tab shows what you would need to build: the minimum number of physical bays at each location so arriving trucks have less than a 5% chance of finding all bays occupied.
Can I use this tool offline?: The map tiles (background map images) require an internet connection. The simulation data itself is served from the application and doesn't need external access once loaded.