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Utrecht Uithoflijn: Development and challenges

27 CAF Urbos trams have been ordered for the Uithoflijn project, with an option for a further 20-26 to eventually replace the city’s existing high-floor fleet.

Utrecht is the fourth-largest city in The Netherlands with a population of 330 000. It has operated a single 20km (12-mile) high-floor tramline since the 1980s, which connects Centraal station with the southern suburbs of Nieuwegein and IJsselstein. Since opening there have been plans for expansion towards the historical centre and also to the ever-growing Utrecht Science Park De Uithof in the east.

The two main bus lines that connect Utrecht Centraal station and Utrecht Science Park are reaching capacity with ever-increasing passenger  numbers, mainly students. Bus line 28 runs through the crowded city and line 12 runs around the historic centre, partly on dedicated infrastructure, using double-articulated 25m vehicles with up to 30 buses/hour operating per direction during peak times. Bus priority at junctions is implemented to avoid bus queues along the route and at stops.

The original plan was for a dedicated bus lane for line 12 that required grade separation of several road junctions to ensure that the journey time of the longer route around the city centre was more attractive than the shorter route through the older streets. But as passenger numbers continued to grow, in April 2012 Utrecht City Council and the Regional Transport Authority decided to replace line 12 with a new 9km (5.6-mile) low-floor tramline from Utrecht Centraal station (CS) to the Utrecht Science Park to cope for future growth; this would also connect with the existing tram network.

Utrecht’s transport policy in 2012 indicated that even more bus lanes might be transformed into tramlines in the future; these would include a route through the middle of the city’s main shopping streets, also replacing bus line 28. This is just one of the reasons that the city decided to procure low-floor trams for the new route.

The existing high-floor fleet that runs between Nieuwegein, IJsselstein and Utrecht Centraal station is nearly life-expired and will also ultimately be replaced with low-floor vehicles, most likely the same ones ordered for the Uithoflijn project. This will give Utrecht the opportunity to operationally connect the new Uithoflijn with the existing tram network, called SUNIJ line.

Procurement of the Uithoflijn

So although the Uithoflijn started off as dedicated bus lane project, a business case was developed for a tramline during the enabling works and the land acquisition period. The civil contracts for construction of a new bus lane were already in place at the time of the policy change. As the business case highlighted that the large number of projected passengers could better be transported with a tram system, all contracts were modified in 2012 to take into account the new requirements. Fortunately the superstructure and the stops had not yet been procured.

Around the same time the Utrecht Regional Transport Authority awarded the regional bus and tram operating concession to Qbuzz, which commenced services in December 2013.

The maintenance contract for the SUNIJ line infrastructure had already been awarded to Strukton, while Stadler – formerly Voith Railservices – had undertaken maintenance of the existing high-floor trams at the current depot in Nieuwegein. To make best use of current practices in Utrecht it was decided to exclude tram operations and maintenance from the Uithoflijn contracts. Also, as financial support was secured, DBFM or DBFMO contracts were ruled out – instead, one contract for the new trams and one contract for the remaining infrastructure were tendered in 2014.

As well as ordering new vehicles for the Uithoflijn, an option for replacing the existing fleet was also requested by the current asset manager; as the rolling stock contract would take longer than the infrastructure contract to complete the two contracts were procured separately. The project team drafted a collaboration agreement to help ensure the integration risks between the trams and the infrastructure are being dealt with. Mott MacDonald was appointed technical advisor to the project team, with local consultant Movares acting as the back office support team for the infrastructure.

On 23 December 2014 a contract for infrastructure construction was signed with the Royal BAM Group – this includes the remaining civil works and the superstructure for the whole 9km (5.6-mile) route, including the stabling facility at the end of the line. A contract was signed on 30 January 2015 with CAF to supply a fleet of 27 five-section 33m low-floor trams; this also includes options to retrofit batteries and supercaps to enable operation without catenary in the university and medical centre area. Options also exist for a further 20-26 trams to replace high-floor trams on the SUNIJ line.

It is anticipated that the end-to-end journey time will be 17 minutes, with between 16 and 20 trams/hour in service during the peak in coupled pairs with an average operational speed of 26km/h (16mph). It is assumed that 24 trams will be required for operational use with three spares for maintenance and to achieve availability targets.

Procurement of the new trams and infrastructure design includes an option to buy longer units in the future to address the increase in passenger usage and offer a higher availability of seating capacity. The total project cost is EUR440m.

Normal daily passenger flow for the new line is estimated at 45 000, projected to rise by 2030 to 60 000, with 50-60% of the passenger flow attributed to student travel.

Utrecht Centraal station

Utrecht Centraal station is a major transport hub, the largest and busiest railway station in The Netherlands, welcoming around 88 million passengers per year (forecast to increase to 100 million by 2030).

The station and its surrounding environment are undergoing a major renewal and expansion programme, budgeted at EUR3.2bn, with overall completion scheduled for 2030. Current work comprises a new train, tram and bus terminal, covered bicycle parking areas (with capacity for 33 000 bikes around Utrecht Centraal station), and a new city hall building above the station.

The Uithoflijn snakes through Utrecht’s main station area, with a double-track length of almost 1.1km (0.7 miles) and stops at both the western and eastern sides of the station. While the tramline is being constructed, Utrecht City Council and its partners are building a new station area; this is much-needed as the area around the transport hub was built in the 1970s. When completed, Utrecht Centraal station will provide seamless connections between trains, buses and trams with an excellent cycle parking area.

Protecting sensitive equipment at Utrecht Science Park

The new line will run from Utrecht Centraal station to the central corridor in De Uithof, a public road that gives access to most buildings and is currently only accessible for public transport, emergency services, pedestrians and cyclists.

The area includes the University Medical Centre, a children’s hospital, university, college and numerous innovative companies and research organisations. As such, this 2.5km (1.55-mile) section of the route features institutions using incredibly sensitive equipment, varying from electron microscopes to the latest MRI scanners. A first review by the project team has identified at least 40 locations that might be affected by the new tramline, with eight in particular identified as ‘hot spots’ where more than one piece of sensitive apparatus is installed.

The project promoter considered a range of options to mitigate impacts to the sensitive equipment, with vibration and Electromagnetic Interference (EMI) issues of main concern. Moving the affected equipment further inside the buildings or to others away from the new tramline was seen to be the most effective solution, but the large number of apparatus involved made that option impractical. In 2013 it was decided to move the tramline 15m away from the original alignment to reduce EMI and vibration levels at one of the hospital buildings. An area of environmental heritage has been offered to construct the new tramline, which is shared with buses and emergency services.

The wheel/rail interface was studied in detail to reduce the vibration levels and trams with low unsprung mass were selected. The infrastructure will also receive dampening in specific areas. To reduce construction noise and vibration the bidders were invited to reduce their work period to a minimum resulting in a ‘big bang construction period’ during the summer of 2016, limiting disturbance in Utrecht Science Park.

To address the EMI issues catenary-free battery operation has also been considered; such operation will increase the weight of the trams but also significantly reduce EMI levels. The conclusions of a feasibility study in 2013 identified that there is considerable interest in the tramway market for battery operation and that the equipment is gradually being developed into ever more viable solutions. However, the decision was taken that whilst there are operational and environmental benefits from using this technology it was difficult to justify on economic and technical grounds.

The technology and operational experience are available to cover 2.5km without catenary in the university and hospital areas, but the charging points at stops would also require specific EMI mitigation measures. The three-minute turnaround time at the terminal stop ‘Park+Ride De Uithof’ is very short, thus limiting the time to charge the batteries. Therefore we have to calculate twice the length of the catenary-free section and operating 5km (three miles) of tramway without charging points was considered too technically risky at the time a decision was made. Another reason not to go for catenary-free operation is the associated cost to equip the whole fleet with battery packs and the associated high maintenance costs.

Sectioning: Proofing new technology

Rejecting a move to even partial battery operation, the promoter has instead chosen to adopt a new ‘sectioning’ technology to address the EMI issues in Utrecht Science Park. Sectioning of the catenary system is estimated to reduce the EMI to acceptable levels using a new patented system designed by the Technical University of Delft together with its partner EM Power Systems.

The implementation includes catenary masts situated every 20m along affected parts of the route and isolated connections in the wiring. This new technology was intended for tramline 19 in Delft, but due to problems with an existing bridge this project has been postponed and Utrecht will be the first place it is installed in full operation.

Extensive testing is included in the Utrecht project programme to confirm that the sectioning system is effective, while the project team has also drafted plans to deal with the eventuality that things may not go to plan. Retrofitting rolling stock with small battery packs is also considered as a last resort and the rolling stock contract is drafted to cater for this event.

In summer 2018 the Uithoflijn will enter operation for passengers, with EMI and vibration testing take place in 2017 and temporary bus lanes to smoothly introduce the service.

Feature originally appeared in August Tramways & Urban Transit (932).