The Daily Sightline has a post today that finds constructing a deep-bore tunnel would result in more jammed downtown streets than building a surface alternative. The post by Clark Williams-Derry, based the state's traffic estimates and analysis by the city-funded firm Nelson\Nygaard, begins with this graphic:
- Nelson\Nygaard
There’s a lot of information in the chart, but you can ignore much of it. The only thing I want you to pay attention to are the orange and yellow bars:
The dark orange bars represent the state’s projections for 2015 traffic volumes under the most likely deep bore tunnel scenario, in which drivers would pay $5.00 to use the tunnel during the afternoon rush hour.
The yellow bars represent traffic volumes under the “ST5″ or “Streets, Transit, and I-5″ plan, using the same traffic model but with some different inputs. Under the ST5 plan, the city and state would make substantial investments in transit and “transportation demand management” to reduce traffic volumes, and also make improvements to city streets and I-5 to help improve traffic flows.[...]
The state’s own traffic models are projecting that a tolled deep-bore tunnel creates worse traffic downtown and on I-5 than the streets-and-transit plan. It’s simply devastating news for the deep-bore tunnel, because it means that the city and state are predicting that a multi-billion dollar tolled tunnel would actually make downtown gridlock worse.
