What is it?
Largest,most technically challenging
Most expensive public works project in US history($13B counting)
Third tunnel (Ted Williams) to Logan Airport
10-lane cable-stayed bridge over Charles River
New access bridge over Charles River
Depress Central Artery below ground
Reclaim land under current elevated Central Artery as park land
Why build it?
I-93 (Southeast expressway) originally designed for 75,000 trips/day;
By 1990, it was 192,000 trips/day
Ttraffic from west wants to go to Logan or downtown
Traffic from south wants to go to Logan or downtown
Ttraffic from north wants to go to Logan or downtown
Local traffic wants to stay local
All the above currently share I-93 in downtown Boston
Why is it so expensive?
One-third of cost is “mitigation” - keeping the CA/T neighbors satisfied
Construction continues without disrupting existing highway(s)
Commuter rail & subway public transit systems active during construction
Federally protected waterway
And much existing infrastructure in place during construction !