RM 12 AND RM 150 INTERSECTION REALIGNMENT AND ROUNDABOUT

Hays County is working to create safety and mobility improvements at the intersection of RM 12 and RM 150 in Dripping Springs.

The effort will include shifting the existing intersection south to avoid impacts to Phillips Cemetery and align with a future roadway that would extend RM 150 to connect to US 290 west of Dripping Springs.

IMPROVEMENTS INCLUDE:

Shifting the intersection to the south to avoid impacts to Phillips Cemetery and align with the future roadway
Installing a one-lane roundabout with the capacity to expand to two lanes if needed in the future

There are currently nine different roundabouts planned in the County. One of these is under construction at the intersection of RM 150 and RM 3237. The video simulation below shows how traffic moves through the intersection.

BACKGROUND

The concept for this intersection realignment was first identified in the 2013 County Transportation Plan, which recommended a realignment from near Oak Springs Drive to connect to RM 12, a deeper cut than the current realignment. The concept included the idea to provide a town center and to align with a future extension of RM 150 to the west of RM 12.

The intersection improvement was vetted again in the development of the FM 150 West Character Plan, which began in 2014 and was completed in 2017. The Plan included recommendations for several intersections to be upgraded to roundabouts in the Dripping Springs and Driftwood areas, with the intent to preserve the natural character, calm traffic speeds, reduce the number of traffic signals, and offer gateway entrances to the cities. As a part of the Character Plan, the County received input from landowners and community members that roundabouts were preferred over traffic signals.

INTERSECTION DESIGN AND CONSTRUCTION

The design process began in 2018 and included additional analysis and traffic studies to compare a roundabout to a signalized intersection:

The roundabout will require approximately 1 acre of additional right of way compared to the signalized intersection to accommodate the intersection realignment. However, the roundabout shows improved long-term efficiency, more efficient flow of vehicles, and reduction of high-speed accidents compared to a signalized intersection. The construction of the roundabout will be more impactful but will result in fewer traffic bottlenecks, reduced congestion, and improved safety in the long term.

Based on this analysis, the roundabout was confirmed as the preferred solution to improve safety and mobility, considering the higher level of services for current and projected traffic.

LIGHTING PLANS

The consultant team, led by American Structurepoint, has included dark sky compliant lighting plans since the initial design submission. After the initial plans were approved, the team took additional steps and coordinated with the Driftwood Historical Conservation Society to identify additional strategies to preserve dark skies such as adjusting the lighting to a warmer color to reduce glare.

TIMELINE

2013 – Hays County Transportation Plan identifies realignment of the intersection
2014 to 2017 – Roundabout identified as preferred intersection treatment through FM 150 West Character Plan
2018 – American Structurepoint contracted to complete design and construction plans
2019 – Traffic counts collected at the intersection
2019 to 2020 – American Structurepoint completes traffic study indicating a roundabout will provide a higher level of service than a signalized intersection
2020 – TxDOT installs signal at the intersection to accommodate traffic volumes
2021 – The County and American Structurepoint evaluate additional alternatives provided by Howard Ranch, which could not be utilized as they do not meet TxDOT design standards
2022 – ROW to be acquired for the 3.7 acres needed for the project
2022-2023– Construction, which begins with utility coordination and relocation and then construction of the roundabout (approximately 10 months total).

All surrounding properties will maintain access during and after construction.

FUNDING

The RM 12 and RM 150 intersection realignment and roundabout design was funded from the County’s general transportation funds. Construction is funded utilizing available funds from the 2016 Road Bond – Safety and Mobility Projects. Bonds typically include a list of projects but are not limited to those projects, and the funds can be used for other transportation projects.