The logic behind Hwy 1 auxiliary lanes instead of through lanes

Dear Street Smarts, Q: While I believe that the lanes being added between Soquel Drive and Morrissey Boulevard are done in a manner that avoided certain regulations that apply to general highway widening, it escapes me how the northbound lane, which ends abruptly at Morrissey only to continue on the other side of Morrissey as an existing lane, will be of any help. It might have been if a large percentage of northbound traffic exits at Morrissey -- like it does at 41st Avenue -- but clearly it doesn't. So we added a third lane, increasing highway capacity by 33 percent, at the cost of millions of taxpayer dollars. Only perhaps 2 to 5 percent of the traffic will exit there, making this expensive addition essentially useless as northbound through traffic backs up at that exit. There is, however, a seemingly easy and inexpensive solution. Since there is already a lane that continues under the Morrissey bridge as part of that very weird Morrissey interchange, perhaps the new outer northbound lane could be routed to that existing under-bridge lane, allowing through traffic all three lanes to aid northbound traffic flow. What were the 'powers that be' thinking? And what can be done - without replacing the Morrissey bridge - to allow all three northbound lanes to flow through? Bruce Koehler via email A: Cost and available right of way at the primary reasons why the Santa Cruz County Regional Transportation Commission opted to construct an "auxiliary lane" rather than a "through lane," said Karena Pushnik, spokesperson and senior transportation planner for the agency. "An auxiliary lane connects an on ramp with the next off ramp, and does not change the intersection, which is what would be needed to create continuous through lanes," she explained. "While auxiliary lanes are not considered capacity increasing, they can improve congestion by pulling the weaving and merging movement out of the through lanes resulting in better flow. As your readers can imagine, costs increase greatly when the interchange needs to be rebuilt because not only is the structure more expensive, but also additional right of way is frequently needed. The cost estimate for replacing the Morrissey Interchange alone is approximately $35 million." Your suggestion to use the lane that goes under the bridge to create a through traffic lane "would create new problems for those wanting to get onto the west or mountain-side of Morrissey," she continued. "This is one reason why changing one connection at this location is not an option." Highway 1 has seen a number of projects in recent years, aimed at improving traffic flow, Pushnik recapped. Those are Mission Street, completed in 2005; Highway 1/17 Interchange Merge Lanes, completed in 2008; and the current Highway 1 Soquel/Morrissey Auxiliary Lanes, which was constructed mostly on property owned by the state. Now the commission is gearing up to install a pair of auxiliary lanes between Soquel and 41st Avenue in 2016-17. "This project is in the environmental clearance phase," said Pushnik. "The estimated $27.5 million for final design and construction of this next auxiliary lane project has not yet been identified. Unless there is a massive infusion of funding, our region will be proceeding with this phased approach to projects in the Highway 1 Corridor, starting with auxiliary lanes." When the commission turns its gaze to improving the interchanges along Highway 1, "almost all of them would have to be rebuilt to allow the space for new through lanes including Morrissey, Soquel, 41st, Bay Porter, and Park, then a new lane the length of the corridor between Santa Cruz and Aptos," Pushnik said.
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