Corridor Access Improvements

Drivers on I-35 use ramps to access mainlanes and frontage roads. Some of the existing ramps do not meet current design standards because they are too short or located too close to other ramps, posing access challenges. Potential solutions under consideration include:

  • Moving ramps
  • Modifying ramps
  • Adding extended entrance/exit lanes
  • Adding intersection bypass lanes

The combination of these modifications will improve mobility and safety along the corridor.

Ramp Modifications

In some areas, such as downtown Austin, the entrance and exit ramps are outdated. They are too short, steep, curved or close together for optimal performance. Some exit ramps end too close to heavily congested intersections, which force drivers to make sudden movements between frontage road lanes after exiting or cause ramp traffic to back up due to frontage road congestion. The I-35 Capital Express Program proposes to modify ramps in these areas to:

  • Better manage traffic flow
  • Maximize operational performance
  • Increase safety
Extended Entrance/Exit Lanes

The I-35 Capital Express Program proposes to add extended entrance/exit lanes in several locations along the corridor. Extended entrance and exit ramps allow a lane for drivers to match traveling speeds between mainlanes and frontage roads before merging. These lanes are typically installed within the distance between an on-ramp and an off-ramp. Extended entrance/exit lanes:

  • Make merging safer
  • Reduce disruption in traffic flow from merging traffic

illustration of extended entrance/exit lanes

Intersection Bypass Lanes

An intersection bypass lane is a one-way road separate from the mainlanes that allows entering and exiting traffic to merge without disrupting mainlane traffic. Intersection bypass lanes allow traffic to bypass frontage road traffic signals at cross streets without being on the mainlanes. Although many area drivers are unaware of having used them, intersection bypass lanes are already in place in several locations within the three-county area, including southbound I-35 at Hester’s Crossing, northbound I-35 at Parmer Lane and southbound MoPac at Duval Road. Intersection bypass lanes are often used between closely spaced interchanges and are vital to the functionality of diverging diamond interchanges, another proposed concept. Intersection bypass lanes:

  • Keep through-traffic separated from merging traffic to avoid disruptions in traffic flow
  • Promote safer lane changes between mainlanes and frontage roads
  • Allow traffic to bypass frontage road traffic signals at cross streets without being on the mainlanes

illustration of intersection bypass lanes

High-Mast Illumination

To improve safety on I-35, TxDOT is installing high-mast lighting, an advanced illumination technology, as part of the I-35 Capital Express Program. Conventional highway lights are typically 50 feet in height and include one to two light fixtures. This requires more poles spaced closer together to properly illuminate the roadway. High-mast lighting can reach up to 150 feet in height and uses six LED bulbs, reducing the number of poles needed and improving visibility. This type of illumination improves safety for roadway users, requires less long-term maintenance and reduces light pollution along the I-35 corridor.

  • Improves safety: High-mast lights are four times more radiant and cast light over both the mainlanes and frontage roads
  • Lowers maintenance cost: LED bulbs are expected to last 15 years, which ensures continued performance and requires less maintenance
  • Lowers energy consumption: LED bulbs use less energy than high-pressure sodium bulbs used in conventional highway lights
  • Reduces light pollution: Light patterns are evaluated before high-mast lights are calibrated and adjusted to focus light directly on the public right of way

Several Mobility35 projects include high-mast illumination, and it will continue to be used in future projects. For more information read the high-mast illumination fact sheet.