The Road reconfiguration is actually quite inexpensive and straight forward, because basically it is a matter of removing the current pavement markings and replacing with marked lanes for the new 3 lanes. Since the Alameda lanes currently are not painted, but instead marked with lane-bumps , only the bumps need to be removed and only a small amount of paint. That cost is roughly $5 per linear foot of road way.
Providing for added administration time, desigin/engineering, signage, and allowing for contigincies costs, the full price would be in the $35,000 range for our section of Alameda. (see FHWA Cost of Road Diet.)
Putting that into perspective, this cost is about the same as a non-injury accident and an order of magnitude less expensive than a moderate injury accident. If you can put a value on the cost of saving a school child from being hit, then please user your own judgement on applying that cost to this perspective.
The stats on a road change from 4 to 3 lanes can reduce accidents by 19 to 47%. With dozens of reported accidents in recent years, the road diet actually saves money and reduces liability and risk. Please add to the discussion by using the Comments section at the bottom of that Pro & Con page.
Why so inexpensive? The road diet from 4 to 3 lanes does not require much. Remove the current lane markings and paint the new lane markings. There is straight forward work for 'design layout' of the new lane markings to insure the design includes the provisional layout for the future sidewalk/curbs.
One of the reasons the road diet is not expensive is that it addresses the traffic lanes, bike lanes, and shorter crosswalks. Yet while allocating room for future improved and ADA compliant sidewalks, sidewalks are a different project and sidewalks are more expensive. Good news is that a road diet could be put in place while funding for the sidewalks is found and budgeted.