3 “Glue-in-the-Road” Tram Track Systems versus Conventional Deep Excavation Methods

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Bristol Trams Need Not Be Like Edinburgh: How Strasbourg Showed a Better Way

(Prepared for councillors and regional transport officials — November 2025)

  1. Introduction – Why This Matters

The Edinburgh Problem: When people think of UK trams, they think of Edinburgh Phase 1 — years of disruption, roads torn up, utilities diverted, businesses suffering, and massive cost overruns. This was not only due to project management issues (7), but also the choice of a deep-excavation construction method (typically 900–1500 mm) requiring wholesale utility diversions.

The Key Point: Modern track systems work differently. They sit shallower (250–400 mm), often above existing utilities, and can be installed much faster with less disruption.

Even Edinburgh learned from its mistakes: Edinburgh’s Newhaven extension (Phase 2, opened 2023) used modern shallow track methods and was delivered on time and within its £207 million budget (8) — a stark contrast to the Phase 1 disaster. The system is now so successful that Edinburgh is planning a major north-south extension estimated at £2 billion, with public consultation launched in August 2025 (9). These methods have been copied to some extent in Birmingham.

And it’s not just about cost — trams transform cities economically: When Croydon introduced its tram system, car traffic in the tram corridor reduced by 20%, demonstrating how trams can genuinely reduce congestion rather than just adding another transport option (10). The tram was specifically designed to connect the isolated New Addington estate — which had high unemployment and was poorly served by buses — to central Croydon, dramatically improving job prospects and accessibility for socially excluded residents (10).

The Trautmann Lesson – Trams as Electoral Winners, Not Losers: When Catherine Trautmann became mayor of Strasbourg in 1989, conventional political wisdom held that trams were an electoral liability. Shopkeepers opposed the tramway, fearing that construction disruption and loss of parking would drive away customers. The right-wing incumbent majority favoured an expensive underground VAL metro system instead (11). Trautmann championed the tramway anyway, emphasising its cost-efficiency (one kilometre of VAL cost as much as four kilometres of tramway) and the city centre revitalisation it would enable (11). The tram opened in November 1994. Rather than being punished at the polls, Trautmann was triumphantly re-elected in 1995 with a first-round victory (11, 12).

  1. Background: Strasbourg’s Tram Revival (1994)

Strasbourg’s modern tram system reopened on November 25, 1994, after a 34-year hiatus. The city faced a challenge similar to Bristol and Bath’s: how to introduce modern tram infrastructure in a dense urban environment with extensive existing underground utilities.

According to White (2009), Strasbourg pioneered the extensive use of slab track and shallow construction methods during its mid-1990s revival. Engineers intentionally designed the tram lines to be built with minimal excavation, laying track directly over existing utilities to avoid expensive diversions (1). These methods have been copied to some extent in Birmingham and Edinburgh Phase 2

This approach has been recognised as best practice in later transit planning analyses (2).

Important UK context: continental practice may not fully transfer to the UK and the utility owner must agree to have its apparatus retained beneath the track. Nevertheless, since most utility damage is caused by the pressure of road vehicles, a concrete slab confers far greater protection — and in Bath would also protect vulnerable cellars. Slab tracks are designed for rapid removal to access utilities and are much easier and cheaper to replace.

  1. The Bottom Line: What This Means for Bristol and Bath

Documentary evidence confirms that Strasbourg pioneered shallow-excavation, embedded track construction designed to lay tram tracks directly above utilities (1). This avoided the cost and disruption of extensive utility diversions and contributed to rapid deployment and cost-effectiveness.

What this means for Bristol and Bath: Many concerns about utility relocation may be addressed through appropriate shallow-slab construction methodology.

UK caveat: Utility owners must agree to retention in place, but modern shallow slabs offer enhanced protection and longer service life.

UK precedents: Strasbourg’s methodology has influenced tram construction across Europe and is already demonstrated in modern UK projects:

  • Edinburgh Newhaven extension (2023): Delivered on time and within £207M using shallow track methods (8), prompting a planned £2B extension (9)
    • Birmingham West Midlands Metro: Successfully uses minimal-dig embedded track systems (2)

This shows clear applicability to Bristol and Bath.

  1. Technical Characteristics of Embedded Track Systems

Modern embedded track systems feature:

  • Shallow installation depth: 150–250 mm
    • Minimal excavation: designed to bridge over utilities
    • Modular construction: pre-cast slabs or thin in-situ concrete
    • Rapid installation: 30–144 m per day (4, 13)
    • Cost advantages: £1.5M–£3M per km versus £5M–£10M for deep-dig (4)

Installation Rate Reference:
Pandrol QTrack® allows installation up to 144 m of single track per team per day, demonstrated on the Tamhai LRT (Taiwan) and Sydney Light Rail (13, 14). It provides vibration mitigation and electrical isolation.

Conventional deep excavation requires 400–600 mm depth, achieves 4–8 m/day, and requires extensive utility relocation (4).

  1. Strasbourg’s Results

Construction Outcomes:

  • Line A opened on schedule in 1994 (9.8 km)
    • Chosen as a cost-effective alternative to VAL metro
    • Tram construction cost ~¼ of the proposed metro (5)
    • Half of total project cost was urban realm improvements (3)

Operational Performance (1995):

  • Daily public transport use rose from 155,000 to 206,000
    • 63,000 new tram riders
    • 30% total ridership increase (6)

The project delivered a functional, high-capacity, low-disruption system.

References

(1) White, P. (2009). Public Transport: Its Planning, Operation and Economics. Routledge.
(2) Bristol & Bath Area Trams Association (2025). Birmingham Tramworks Show Utilities Don’t Always Need to Be Moved: Minimal-Dig Track Methods in Action – A UK & International Perspective.
(3) Freemark, Y. (2010). Envied the World Over, Strasbourg’s Tram Expands Again. The Transport Politic.
(4) Bristol & Bath Area Trams Association (2025). Glue-in-the-Road Tram Track Systems versus Conventional Deep Excavation Methods.
(5) Wikipedia contributors (2025). Strasbourg tramway.
(6) P2 InfoHouse. The Tram as a Key Element of Urban Transport Policy.
(7) Bristol & Bath Trams (2025). Why Was the Edinburgh Tram Fiasco So Expensive and Late?
(8) Edinburgh Trams (2023). Newhaven Extension Project.
(9) City of Edinburgh Council (2025). Tram North-South Extension Public Consultation.
(10) Bristol & Bath Area Trams Association (2024). Beneficial Effect of Croydon Tram.
(11) Wikipedia contributors (2025). Strasbourg tramway.
(12) France Télévisions (2020). Municipales 2020 : Catherine Trautmann.
(13) Pandrol (2025). QTrack® Embedded Ballastless Track Fastening System.
(14) Pandrol (2019). Pandrol Awarded CTCI Supplier of the Year

 

Links to other memoranda in this series:

    1. ComparativeBenefits of Trams and Buses in Urban Public Transport
    2. Dispelling the myth that trams need special seperate segregated path through traffic

 

  1. Why trams are essential to improve city productivity
  2. Overhead wire-freeTechnologies for Tram Propulsion
  3. Birmingham Tramworks Show Utilities Don’t Always Need to Be Moved: Minimal-Dig Track Methods in Action – A UK & International Perspective

Technical Memorandum 3 – Embedded “Glue-in-the-road” Tracks

 

Appendix: List of Embedded Tram Track Systems

7. Other Shallow Track Installs

Europe
Germany: Berlin, Munich, Dresden, Leipzig, Frankfurt (Main), Cologne, Düsseldorf, Stuttgart, Karlsruhe, Hannover, Nuremberg
France: Bordeaux, Nice, Lyon, Strasbourg, Montpellier, Nantes, Paris
UK: Manchester (Metrolink), Birmingham (West Midlands Metro), Edinburgh, Sheffield, Nottingham, Croydon, Coventry (VLR), Bradford
Poland: Kraków, Poznań, Warsaw, Bytom, Wrocław, Gliwice, Łódź, Toruń, Gorzów
Austria: Vienna
Switzerland: Various modern tram extensions
Netherlands: Various tram lines with double-block concrete slab track
Spain: Barcelona, Madrid
Italy: Florence, Rome, Milan, Turin
Turkey: Istanbul, Ankara

North America
USA: Portland (Oregon), Seattle (Washington), Dallas, Houston, Charlotte, Tucson
Canada: Toronto

Asia
China: Tianjin, Shanghai
South Korea: Seoul, Busan
Japan: Urban tram systems

Australia
Melbourne, Sydney, Gold Coast

South America
Rio de Janeiro (VLT Carioca)

Links to other memoranda in this series:

  1. ComparativeBenefits of Trams and Buses in Urban Public Transport
  2. Dispelling the myth that trams need special seperate segregated path through traffic
  3. “Glue-in-the-Road” TramTrack Systems versus Conventional Deep Excavation Methods
  4. Why trams are essential to improve city productivity
  5. Overhead wire-freeTechnologies for Tram Propulsion
  6. Birmingham Tramworks Show Utilities Don’t Always Need to Be Moved: Minimal-Dig Track Methods in Action – A UK & International Perspective

 

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