AI can be installed at all 9 of the intersections for a cost of only $440,000, while the 9 roundabouts will cost over $200 Million.
AI will use the current Opticom system at each intersection which allows the fire departments to turn the lights green in the direction that they are traveling and thus allow the fire trucks to maintain highway speeds through the intersections, while the 9 roundabouts will add as least 5 minutes (32 seconds per roundabout) to their emergency response times according to the Monterey County Regional Fire District, and that is assuming that the roundabouts are not clogged with drivers that are unfamiliar with exiting them in an emergency.
AI can be installed without any traffic disruption and without any impact to the environment or need for an Environmental Impact Report since it can use the existing intersections and the current signal lights, while the 9 roundabouts will require acquisition of land at each intersection, impact the environment significantly and cause years of extreme traffic congestion while the roundabouts are being built and commuters having no other option for travel.
AI has been shown to decrease traffic congestion by 25-40%, while TAMC says that 9 roundabouts will only reduce congestion by 5 minutes (13%) in the PM peak commute but actually increase commute time in the non-peak commute (20 hrs/day) by causing all vehicles to slow to 15 mph, 9 time in 8 miles.
AI has decreased vehicle emissions by 20% by optimizing traffic flow in real time, while 9 roundabouts will increase emissions by forcing all 30,000 vehicles per day to slow to at least 15 mph and then accelerate to 55 mph, 9 times in 8 miles and studies have shown that emissions from vehicle acceleration are 5-10 times more that emissions from idling and the only idling that the roundabouts claim to reduce is the 5 minutes in the PM commute.
AI can monitor actual traffic in real time, communicate between intersections and adjust the signals accordingly to provide efficient flow where and when it is needed most, thus decreasing congestion, while the single lane roundabouts are a permanent physical structure that cannot adapt in any way to changing traffic patterns during the day or adapt to unusual traffic challenges like Laguna Seca events.
AI can adapt and be upgraded as technology evolves and traffic increases and done so without any traffic disruption, while roundabouts are permanent structures that cannot adapt to anything without major construction demolition and rebuild which will cause even more congestion during the process.
AI can adapt better to changes along Hwy 68, such as airport expansion or additional housing being built since it can be programed for those changes including addition of more lanes at an intersection, while roundabouts are physical structures that cannot be changed without major demolition and construction.
AI will move traffic efficiently and not increase the number of times vehicles are required to slow down, thus decreasing the chance of rear end collisions which comprise 70% of the current collisions on this stretch of Hwy 68, while 9 roundabouts will force all vehicles to slow down to 15 mph or stop to yield to cross traffic, 9 times over 8 miles, 24/7, 365 day per year which increases the potential of more rear end collisions.
AI adapts to dominate traffic flows on the main line which is the case on Hwy 68 where that traffic volume is much greater that any side road traffic, while roundabouts work best in situations where traffic volume is balance in all four directions which is definitely not the case on Hwy 68. In non-balanced flows, traffic from the side streets has difficulty in entering the roundabout since needing to yield to the main flow.
AI uses existing signals which are very familiar to the driving public, while roundabouts are very new and challenging to many drivers, both local and out of town, thus they will not operate as the computer simulation does, and will not function as planned
Smart signals seem to be a short term no-brainer. If the result is not satisfactory, roundabouts should be considered, one at a time, and on a pay-as-you-go basis, responding to the actual residual congestion. I would expect roundabouts at Del Rey and Laureles might be useful since those are through-route junctions and subject to much greater use during track events. There is room to make them big enough to not cause a problem for trucks and emergency equipment.
If the bottlenecks in the middle are smoothed out, the two ends should become easier as well. The entrances to the airport and Ryan Ranch industrial park don’t seem to be enough of a problem at this time to warrant more than adjustability for the signals. That may change in the future, or it may not.
Wildlife passages are a good idea whenever they can be worked in.
All this should be viewed in perspective – anyone used to commuting in the Bay Area would view the Hwy 68 delays as minor. We do get spoiled.