About the Henley Street Bridge

Today, TDOT announced that the Henley Street Bridge won't open until February, 2014, almost 8 months after the initial deadline.

The reason is that the piers are more structurally deficient than previously believed.  TDOT claims that they couldn't have known this until now.  However, I question why they didn't start pounding the piers the day the bridge was mostly demolished (which would have been quite a few months ago).  They could have known the state of piers then and started rebuilding those with a different contractor as Britton built the approaches and safe piers.

Back on topic.

At the TDOT James White Parkway Meeting, TDOT claimed that 75% of the vehicles travelling across the Henley Street Bridge made their way to highway, thus bypassing downtown.  They were claiming that vehicles were using Henley were using it as an access to the highway, thus justifying a bypass of downtown.

However, let's look at the data from 2011 via the Knox Trans website.

There were 42,000 cars traveling Henley Street Bridge in 2011.  We'll assume that 21,000 (half) were going northbound and 21,000 were going southbound.

There were 47,00 vehicles on Henley north of Clinch, so 23,500 cars each direction.

That means that between the bridge and Clinch, NB traffic increased by 2,500.

The report states that 11,000 vehicles are observed on the NB side of the Henley Connector.

So if 21,000 vehicles cross the bridge, and 11,000 are observed at the interstate offramp,  that would mean that 53% of the vehicles crossing the bridge end up at the interstate.  And if you technically include the fact that some percentage turn onto Cumberland or on to Main, this number would be even less.  If you think that 10% of the cars between the bridge and Clinch turn off Henley, the percentage would be less than 48%.

Not bad for TDOT math.  Only a 25% error.