The six mile stretch of the 120 Bypass is arguably the most crash-prone freeway in the Northern San Joaquin Valley.
An accident severe enough to require a response from the California Highway Patrol happens, on average, once every two days. That does not include fender benders that some daily commuters say happen with almost as much frequency.
There were 1,261 accidents handled by the CHP on the 120 Bypass during the past seven years. That included 11 fatal crashes and 815 injury accidents. The majority of those accidents are in the eastbound lanes within 1.5 miles of the Highway 99 interchange.
The human cost is staggering as is the economic cost.
A report issued in 2011 by the American Automobile Association put the economic cost of a fatal accident at an average of $6 million and the average cost of a serious injury accident at $126,000.
The AAA projections were made using Federal Highway Administration data. The FHA information  placed dollar values on 11 components: property damage; lost earnings; loss of household activities; medical costs; emergency services; travel delays; vocational rehabilitation; lost time at work; administrative costs; legal costs; and pain and lost quality of life.
Even if the actual loss was only a half of the AAA estimates — $3 million for a fatal accident and $63,000 for an injury accident — the seven years of carnage represents financial losses of $94.3 million.
Caltrans is working at getting in place short-range improvements such as enhanced signage to alert drivers of traffic slowing ahead as well as the upcoming eastbound lane split.
There’s money set aside for the design of a long-term solution but no money secured yet for the actual construction.
The solution is not as straight-forward as it may seem. The Austin Road interchange with its overpass built in 1955 poses a major roadblock.
Not only are there off and on ramps in close proximity to the 120 Bypass/99 interchange, but the Austin Road bridge makes it impossible to squeeze in another transition lane with a reasonable merging distance.
There are two alternatives are being considered for the long-term improvement.
The first could cost as much as $40 million. It would widen the connector to southbound 99 to two lanes, construct braided ramps (that are physically separated from freeway lanes) at the Austin Road interchange and replace the Austin Road crossing to provide an additional southbound 99 through lane. In some instances braided ramps require constructing bridge structures to send traffic above other lanes.
The second would cost upwards of $29 million would widen the connector to two lanes, permanently close Austin Road on and off ramps and replace the Austin Road overcrossing to provide an additional southbound 99 through lane.
The goal the San Joaquin Council of Governments and Caltrans has put in place to tentatively start work in the summer of 2021.

To contact Dennis Wyatt, email dwyatt@mantecabulletin.com