Thornton staff outline process for permanent road closures; Glen Eagle residents seek relief from school-related cut-through traffic

Brett, a city staff member, introduced a presentation on the authority and process for permanent closures of city-owned streets and then turned the briefing over to Daryl Olsen, Thornton's traffic engineer, who reviewed legal constraints, process steps and a Glen Eagle Estates case example.

Olsen told the council the city has general authority to change street layout and close city-owned connections, but closures can conflict with approved plats and the city's development design standards (cited in city code section 18-6-677). He said a permanent closure of an existing roadway connection is considered a matter of significant impact and that a public hearing pursuant to city code section 2-54 should be held; any vacating of right-of-way would require an ordinance adopted by council.

Using Glen Eagle Estates and the adjacent Villages at Riverdale as an example, Olsen described how recently opened schools (Riverdale Ridge High School and a nearby school) increased congestion at the 120th Avenue and Riverdale Road intersection and prompted drivers to use neighborhood streets as cut-throughs. Olsen presented plat history showing the Villages at Riverdale connection (100th/130th Place) was platted in September 2002 and Glen Eagle recorded shortly after; temporary cul-de-sac easements were included in the plats and were intended to be removed once future connections were completed.

Traffic counts in the study area show roughly 82% of neighborhood traffic enters from 120th Avenue and Riverdale Road and about 18% from Villages at Riverdale, indicating drivers are avoiding the intersection. Olsen noted potential costs and impacts of constructing cul-de-sacs where the connection would be removed: full reconstruction, curb and gutter, drainage work, right-of-way acquisition and potential effects on adjacent properties and utilities (including an oil and gas utility easement that requires notification). He also warned that closing a connection may redistribute traffic and create issues elsewhere, such as parking or illegal dumping.

Olsen recommended two parallel tracks: continue working with Adams County to pursue intersection improvements (Adams County is pursuing an NAA PME grant aimed at congestion and pollution mitigation and a roundabout was discussed as a preferred solution) and pursue interim options with the school district and police (staff described traffic-flow changes for the nearby schools that would be implemented over spring break). He also recommended that, if the city seeks a closure, it first pursue a one-year temporary closure (using substantial barricades) to evaluate impacts before committing to permanent changes, and only proceed with cul-de-sac construction after assessing right-of-way and drainage needs.

Councilmembers asked about cost estimates (staff said none had been prepared but that cul-de-sacs would likely require substantial reconstruction), outreach to Villages at Riverdale residents (staff said they had not yet heard from that neighborhood and would engage them), and the mechanics of a temporary closure (one-year trial using concrete barricades or similar measures). Staff said an iWatch neighborhood meeting with Glen Eagle is scheduled and that Tony and other staff members have met with an Adams County commissioner to explore partnership options.

Staff concluded that the priority is partnership with Adams County to address the root congestion issue at the intersection; if Adams County does not pursue the grant/project, staff will return with finer planning (including costs, outreach plan and potential impacts) before the council considers any permanent vacation of right-of-way.