Today I'm talking construction costs. I did some breakdown of the costs for the soon-to-be-built first tramway line in Bologna. A recap:

16.8 km

511m€, including 26 32m-long vehicles

The "gross costs" is 30m€/km

Bu the itemized breakdown is more interesting

Out of 511m€:

63m€ (12%) are soft costs for management, land acquisition (only 3.5 m€, essentially for the depot and maintenance center) contingencies, design and technical services, etc.

43m€ (8%) are sales taxes, accounted separately in public works for reasons

The remaining 404m€ are the actual HARD infrastructure and the rolling stock

Rolling stock accounts for 78m€ (15%), 3m€/each for 32m-long vehicle with battery for the 2km long wireless central section

The remaining 326m€ (63%) is the actual hard infrastructure.

But even more interesting is the breakdown of the hard infrastructure:

roughly 245m€ (47%) are for the civil engineering (tracks, stops, roadworks, depot, etc.)

the remaining 80m€ (15%) are for OLE, ESS, electrical, signaling, security etc.

If you take the civil works only (245 m€):

-79 m€ (33%), are for the maintenance& control center, headquarters, depot, etc. for both this line and the second one (there is enough place for 40 vehicles).

-3 m€ are for a secondary depot at the other terminus

Other big civil engineering costs not directly related to the line are:

13m€ for a new grade separated car intersection near the terminus

14m€ for the "mobility center"+park&ride+green area+other amenities at the western terminus

All the elements of the two previous tweets, that accounts for 45% of the civil works, are almost all concentrated at the western terminus (see image).

The 16.8km of the actual civil works along the line account for 131m€

That is 8M€/km compared to a 30m€/km gross cost

If we break down the costs even further, 100m€ are for the actual tramway RoW: the tracks (80m€) and the track bed (20m€).

The tramway structure itself costs 6m€/km.

Oversimplifying, we can say that this is the real extra costs of a tramway compared to a Trolleybus-BRT

40m€ are the costs for redesigning the road corridor: paving, sidewalks etc. That is 2.4m€/km for associated roadworks

Utilities relocation is quoted at 13m€, that is less than 1m€/km

Electric traction is 38m€ (2.3m€/km), with 15m€ for OLE (< 1m€/km) and 18m€ for the 10 electric sub stations (1.8m€/each)

considering only tramway platform and electrification, the additional cost of a tramway vs a diesel BRT infrastructure is 8.3m€/km

I could add that there are other costs not directly related to the transit project itself but are accounted for in the budget: a short section of the canal in the city center will be opened up and redesigned together with the tramway. This will cost 3.2m€

Other interesting elements: stations, which have 42m-long island or side platforms with a small shelter, benches, vending machines etc., will costs between 250-400k/each, roughly half for civil works, the rest for electronics/electrical/information system etc.

The depot an maintenance center is indeed a very large part of the final costs (but, in these case, it includes also the capacity for the second line). The actual tramway RoW and electrical equipment are a small part of overall cost:
8.3m€/km out of 30m€/km, roughly a third

Of course those are hastily made calculations, and you cannot really separate the costs for the depot from the line (both are needed for a functioning infrastructure), as are the costs for redesigning the streets (many with new cycle lanes, trees, sidewalks etc.)

Indeed, there are some costs not directly related to the line itself: parking places built to partially replace the ones lost along the line, new roads and a large grade separation for some 20-30m€ in total. The line would have worked perfectly even without that.

It is important to understand that a large infrastructure project is in reality many bounded projects and gross costs can hide many details that are important to understand

Little addendum. Those costs are based on calculations based on itemized unit costs listed in yearly updated regional reference costs for public works.

When costs are not listed, a breakdown analysis is produced, adding factors: materials/hours worked/tools rent etc.