squealing on curves. Twenty greasing installations were installed in IJsselstein, in Nieuwegein and at several places in the city of Utrecht. In 2023, the rails are to be ground so that tram wheels will optimally contact the rails. These efforts are to reduce noise and noise complaints. SUNIJ renovation (2020–2021) Between 31 May and 4 July 2020, the SUNIJ line was shut down in stages in order to renovate the line. The main work was to lower and lengthen tram platforms to accommodate new low-floor CAF trams. The project also included upgrades to the line's infrastructure (signals and switches) and work to stabilize the tram roadbed. Tram service was replaced by buses. Passenger service from Utrecht to Nieuwegein Zuid was originally to have resumed on 21 September, and to IJsselstein Zuid on 26 October. However, the Dutch rail safety authority ILT (Inspection Leefomgeving en Transport) blocked the opening declaring that the project was not a renovation but rather new construction, which required different documention to proceed to opening. There was an extra delay in opening line 61 due to work to reinforce the tram roadbed near IJsselstein Zuid. The opening dates were then revised to January 2021 for line 60 to Nieuwegein Zuid and February 2021 for line 61 to IJsselstein Zuid. From 10 November 2020, day time tests resumed running a coupled pair of CAF trams between Utrecht and Nieuwegein. (Previously, tests had been done at night in the summer of 2020.) Technical tests were carried out such items as for traffic signals and turnouts. At each tram stop, the exact position where a , two-tram consist should stop was determined in order to reserve a boarding location for wheelchair users on the platform. During this test phase, trams operated below . After ILT granted an operating permit, tram operators were trained and system testing conducted, timed against an operating schedule. Line 60 from Utrecht Centraal to Nieuwegein Zuid reopened on 3 January 2021 using 7-section CAF trams running 8 times per hour from Monday through Saturday. (The frequency would be reduced to 4 times per hour after line 61's reopening.) Prior to the renovation, the Stadscentrum tram stop was located on the south side of the street Passage at the entrance to the Cityplaza shopping mall. After the line reopened on 3 January 2021, the stop had been temporarily relocated north of Passage between the streets Schouwstede and