I feel that it makes no sense to address your leading questions.
If you want to argue that retrofitting schools to address line of sight issues will cost about the same as all the fortifications you suggested, please do so.
Is there some sort of case study? As far as I can tell, there is no verifiable data showing how effective these policies are. So, while many of these policies make sense, and we should implement those that have little cost or drawback (because why not), it is unfeasible to do major retrofits to most schools in unproven hopes of protection.
Meanwhile, finding out and addressing the root causes of mass shootings and other forms of gun violence seems like a more practical way to get effective solutions.
Yes, there are case studies. Let me repost
this joint report from Every Town (a gun control advocacy organization), AFT and NEA (major teachers/educators unions) that mentions some:
Every Town Research, AFT & NEA - Keeping our Schools Safe wrote:...
Implement Basic Security Upgrades
In 2017, as the sound of gunshots echoed across campus, school administrators at Rancho Tehama Elementary School in Rancho Tehama Reserve located in Tehama County, California, made a critical decision. They immediately put their campus on lockdown, ushering students and teachers inside, locking internal doors, and locking out anyone who would try to enter.79 As a shooter approached, crashing through an external gate, he was unable to access the school building. Frustrated, he gave up and left school grounds before ultimately being stopped by law enforcement.80
Physical security is a critical intervention point to keep guns out of schools. The most effective physical security measures—the ones that are agreed on by most experts—are access control measures that keep shooters out of schools in the first place. As a secondary measure, internal door locks, which enable teachers to lock doors from the inside, can work to deter active shooters who do achieve access, protecting students and allowing law enforcement time to neutralize any potential threat.
Of course, one of the biggest challenges with security upgrades is maintaining a welcoming school environment. Schools cannot become prisons. Everytown, AFT, and NEA endorse basic security measures universally recommended by school safety experts, like access control and internal door locks, while recommending that schools also consider other expert-endorsed security measures based on local conditions.
In 2018, as the shooter arrived on the campus of Marjory Stoneman Douglas High School in Parkland, Florida, several critical access control failures gave him easy access to the school. He was dropped off outside of a perimeter fence. This fence had a gate that was open and left unstaffed.81 The shooter took advantage of this and entered the school campus. As he entered Building 12, where the shooting happened, he exploited another critical safety failure, as the door was left unlocked and accessible to all.82 In fact, the Marjory Stoneman Douglas Public Safety Commission found that “The overall lack of uniform and mandated physical site security requirements resulted in voids that allowed [the shooter] initial access to MSDHS and is a system failure.”83
Most experts, including the Marjory Stoneman Douglas High School Public Safety Commission and the Sandy Hook Advisory Commission, agree that access control should be a component of any school security plan.84 Preventing unauthorized access to schools through fencing, single access points, and by simply ensuring doors are locked can keep shooters out of schools. State legislatures should provide funding for access control measures for schools to make sure that would-be shooters cannot have easy access.
INTERIOR DOOR LOCKS
In the shootings at both Sandy Hook Elementary School and Marjory Stoneman Douglas High School, teachers had to step outside of their classrooms while the shooting was underway in order to lock their doors. This exposed the educators and students to danger. Doors that were left unlocked were unsecured and vulnerable. That is why school safety experts, like the Sandy Hook Advisory Commission, agree that schools should make sure that classroom doors lock from the inside as well as the outside.85 Interior door locks can mean the difference between life and death in an active shooter situation. Everytown, AFT, and NEA recommend that all schools equip doors with interior door locks to help prevent shooters from gaining access to classrooms.
So how did you come up with the cost?
This California Dept of Education guide
recommends sizing a senior high school serving 2,400 students at 52.7 acres. This would amount to a little under 2.3m sqft, if the site is a square then it would amount to around 6,060 linear feet of a security fence. This site says a "high-end" security fence costs $100-$400 per linear foot
, so just taking the cheapest would mean a very large high school require some $600k for high-end security fencing. The Uvalde Consolidated School District has 10 schools
so taking this estimate would amount to devoting ~$6m for fencing 10 large high schools each serving 2,400 students. The only school in UCSD I could find information about was Uvalde High, which has an enrollment of 1,250 students so chances are it would be substantially cheaper than @BlutoSays's estimate of $75m to fence all the schools in the district unless I'm missing something.
If we took Texas' minimum recommended area site from the American Planning Association
of 15 acres for high schools costs obviously come down proportionally, and if we stopped assuming they're all high schools (only 3 out of 10 are) then costs come down by even more. Same if we take CA's guide keeping actual enrollment for each school into account.
A full-blown wall would probably be better, yes, but a security fence would probably suffice for stopping an external shooter from entering the classrooms and killing 20 people in a single go. And no, it doesn't cost $75m, it probably costs far less than $6m, maybe even less than $2m. According to the District's last budget (the budgets are available here
), the federal government is contributing a bit over $1.9m to the current one.