The project to build a four-lane toll road with a pedestrian trail that connects Loop 1 to FM 1626 in Hays County has been sent back into environmental evaluation, but the agency in charge of designing and constructing the project says construction is still on track for spring 2016.

The Central Texas Regional Mobility Authority made 10 revisions during final design work and sent the project back in June to the Texas Department of Transportation for re-evaluation, Mobility Authority Engineering Manager Sean Beal said. Some of the revisions included a reconfiguration of the interchange at Loop 1 and SH 45 SW, a reduction of shoulder width on Bliss Spillar Road and other footprint reductions.

As of mid-October, TxDOT is continuing its environmental re-evaluation, which may be complete with the final design by the end of the year, Mobility Authority Manager of Communications Rick L’Amie said.

Beal said the environmental re-evaluation will go through the same amount of rigor as the first environmental study, but the proposed changes will not lead to more significant issues that could affect the project.

L’Amie said the environmental re-evaluation will not delay the project. The SH 45 SW project is estimated to cost $100 million.

Previously, TxDOT completed the first environmental study in January so final design work could begin.

The need for the SH 45 SW project came about after neighborhoods and the population in Southwest Austin grew, L’Amie said.

“What this traffic solution aims to solve is a lot of the cut-through traffic in Southwest Austin neighborhoods,” L’Amie said.

Beal said once drivers get off neighborhood streets and get on commuter roads with no stoplights or signs, such as SH 45 SW and Loop 1, there will be travel time reductions. Drivers from FM 1626 who travel north on Manchaca Road and west on Slaughter Lane to reach Loop 1 will save about 17 minutes once SH 45 SW is built, according to the Mobility Authority.

Some groups, such as the South Brodie Neighborhood Alliance, support the SH 45 SW project.

Although Southwest Austin commuters may benefit from SH 45 SW reducing travel time, a local nature center off Loop 1 near the proposed toll road is concerned about its completion.

Mike Abkowitz, interim executive director of the Lady Bird Johnson Wildflower Center, at 4801 La Crosse Ave., said via email the additional vehicle traffic will likely result in more noise at the center. The noise could impact visitor attendance, rentals and resulting revenue, he said, adding that he is unsure at this time if the center could shut down.

“But [shutting down] is within the realm of possibility,” Abkowitz said.

A noise analysis was conducted as part of the environmental study, but testing was not conducted near the center because it was outside the study area, according to the Mobility Authority. The Mobility Authority anticipates a negligible noise increase at the center because of its distance from SH 45 SW, L’Amie said.

Bidding for a construction contractor is estimated to occur in January or February 2016, followed by a ground breaking in spring 2016.