On Tuesday, a deadly crash shut down key State Highway 45 on-ramps to southbound MoPac in Williamson County, turning the evening drive into a slow grind as investigators worked the scene. Deputies and Texas Department of Public Safety troopers closed the ramps while they processed what officials described as a collision involving a fatality, and drivers headed toward Loop 1 ran into heavy delays.
The closure included the County Road 172 on-ramp near the La Frontera area, a busy funnel for commuters trying to reach southbound Loop 1. Authorities said they did not have an estimated time for reopening as the investigation continued.
In a public post, the Williamson County Sheriff's Office urged drivers to steer clear if possible, writing that motorists should "use caution in the area, expect delays, and seek alternative routes" and that no reopening time was yet available, according to the Williamson County Sheriff's Office. The agency said its traffic unit, along with Texas DPS troopers, is investigating the earlier crash that left at least one person dead.
Officials described the incident as a "previous collision involving a fatality" as they put ramp closures in place from SH 45 to southbound MoPac, including the CR 172/La Frontera on-ramp. As of the time of the sheriff's post, they had not released the name of the person who died, information on any additional injuries, or what might have caused the wreck.
Where the closure is
The shutdown affects ramps at the SH 45 and Loop 1 (MoPac) interchange in the La Frontera and CR 172 area of western Round Rock, a major connector for drivers moving between the SH 45 toll lanes and southbound Loop 1. County mapping shows CR 172 (La Frontera Blvd) feeding traffic onto SH 45 and toward the MoPac ramps, which is why that specific on-ramp is highlighted in the sheriff's alert. Williamson County GIS and regional toll maps both identify CR 172/La Frontera as the primary connector for that interchange.
How to reroute
Drivers aiming for southbound MoPac should be ready for detours and leave extra time. Alternate options include using I-35 or nearby arterials like McNeil Road and La Frontera Boulevard to work around the blocked ramps. The City of Round Rock transportation plan identifies McNeil and La Frontera as key links between SH 45 and the I-35 and MoPac corridors, routes that are likely to pick up spillover traffic while the closure is in place. Expect slowdowns on surrounding surface streets as diverted drivers seek a way around the scene.
Investigators at the scene
Williamson County deputies and DPS troopers remained on site to investigate and clear the crash, and the Sheriff's Office asked anyone with information or dashcam footage to contact its investigators. So far, agencies have not released detailed findings about what led up to the collision, and no estimated reopening time was included in the department's advisory.
This story will be updated if Williamson County officials or TxDOT release additional information or announce when the SH 45 to southbound MoPac ramps are expected to reopen.
