This nugget in the RFP tells us why the road was open.
3. Traffic Control Restrictions:
Lane closures shall occur only during non-peak hours on non-event nights. Non-peak hours are 9:00PM to 5:30AM Sunday through Thursday and 11:00PM to 7:00AM on Friday and Saturday Nights. A lane may only be closed during active work periods. Pacing Operations will be allowed during the approved lane closure hours. All lane closures, including ramp closures, must be reported to the local emergency
agencies, the media and the OWNER. Also, the Design-Build Firm shall develop the Project to be able to provide for all lanes of traffic to be open in the event of an emergency.
I suspect that Tamini Trail is very heavily used and there are probably no go detours. Local govt dictated that traffic should be minimally impacted. Maybe even the state.
My opinion is that for the most part this bridge was not going to solve the problem they were looking to solve. That is to provide a safe passageway that people would used. Unless you put up barriers to pedestrians on the streets, they will still use the fastest and most direct route. In creating this preferred alternative route they were/are going to create obstacles to use. They wanted it to become an “event space”. How would people cross if such space was being used and passage blocked. It certainly would limit the types of events.
It would have been far cheaper to build drop gates such as at rail crossings creating safe passage lanes. But that would not be sexy.
Lastly, the max of the bridge contract is $9,388,076. The rest of the $15 is for other costs. You can’t build bridges for that amount.