Why Northgate Link Delay

Previous posts have questioned why Sound Transit's Agency Progress Report Program Schedules since June 2020 have shown the Northgate Link Revenue Service was Sept 26, 2022, a year's delay from the Sept 2021 in other charts in the reports.

The April 7th release of the February 2021 Progress report continues the delay and a potential explanation, the following number 2 "Risk Management"

If there is a problem during vibration certification testing and analysis, acceptance by UW may be delayed delaying RSD (Revenue Service Date)

This issue was originally included as the number 9 "Risk Management" concern in the July 2020 report"

Operation of the Light Rail system may exceed thresholds for noise and vibration or EMI as required by the U of W and are delayed to provide further mitigation for these impacts.

Light rail train noise had been a concern for years with homes along Central Link needing sound proofing and Bellevue requiring Sound Transit shield homes hundreds of feet away from tracks and across major roadway.  The concern over  vibration is the result of a "Master Implementation Agreement" (MIA) between Sound Transit and University of Washington regarding operation of light rail in a tunnel underneath campus.  

Nearly eight years ago a post on this blog "ST HighRisk/No Reward Northgate Extension" included the following regarding why the need to meet MIA requirements for any light rail tunnel under the campus:

Protects research and instruction by defining levels of vibration and magnetic field (MF) thresholds which ST shall not exceed without advance approval by the University includes a monitoring program to assure real time compliance as well as liquidation damages if any threshold is exceeded by ST.

The tunnel risks resulted in:

ST and UW agreed upon a lump sum payment of $20.000.000 by ST to the University as consideration for the terms, conditions and easement contemplated in the MIA as well as reflecting the allocation of risks and obligations afforded to each party associated with the first two segments of the Northgate Link program on and under the Seattle Campus east of 15th and south of 45th.

They also resulted in the following tunnel design requirements:

In order to minimize vibration and MF, Sound Transit shall have a continuing obligation to employ over the term of this Agreement, the most current and effective design and material, including but not limited to quadrupole mitigation techniques at least within the limits of the University's Seattle campus, floating slabs and ultra straight track designed to produce minimum undulation and vibration, particularly at low frequencies, from the University of Washington Station to at least the northwest boundary of the University's Seattle campus.

Even with these probably expensive design features the completed tunnel light rail must demonstrate compliance during "pre-Revenue Service Test"

In no event shall Sound Transit commence Revenue Service on University Properties if (Vibration and MF) Thresholds are exceeded.

Other parts of the MIA included huge fines if the tunnel took too long or if problems during service resulted in vibration or MF exceeding limits.  The MIA assured any disputes regarding these issues would likely be resolved in favor of the University.

Again this was a known risk in 2013. Sound Transit began University Link tunnel operation in 2016.  They had ample opportunity to obtain vibration levels and magnetic field(MF) thresholds for light rail operation in a tunnel.  It's not clear whether any of the proposed mitigation techniques were incorporated in the tunnel design under the campus.

One would have thought Sound Transit was confident of being able to operate light rail trains in the tunnel under the campus before spending billions extending light rail to Northgate and beyond to Lynnwood.  Again the first indication of the potential problem was the July 2020 Agency Progress Report. (A month after the June Progress Report first showed the year delay in revenue service)

Presumably testing to determine compliance with MIA was the reason for the March 10th January2021 Progress Report "Key Project Activities"

Pre Certification Vibration testing between University of Washington Station and U District Stations completed with K1 cars, Siemens Car Testing planned 2/1/21.

The January report didn't include the vibration issue in the 9 Risk Management issues suggesting the test had shown compliance.  Instead the April 7th February 2021 Progress Report, 2 months after initial testing, included the delay and the vibration demonstration as the number 2 concern,  raising all sorts of questions.

Sound Transit needs to provide answers as to whether vibration is the reason for the delay and if so how they intend to "mitigate" the problem.