The Texas Department of Transportation began the search this year for the best long-term solution to improve the heavily-travelled I-45 and Woodlands Parkway/Robinson Road interchange.

TxDOT started a planning and environmental linkage study along I-45 from Beltway 8 to Loop 336 in Conroe that could take up to three years to complete. The interchange is severely over capacity, which must be addressed by TxDOT and Montgomery County Precinct 3 with both short- and long-term solutions, according to the Houston-Galveston Area Council’s South Montgomery County Mobility Study, which was completed in September 2015.

“The interchange of Woodlands Parkway/Robinson Road and I-45 is one of the most congested corridors in all of south Montgomery County,” said Matt Beasley, Montgomery County Precinct 3 chief of staff. “The existing interchange was designed for rural use. As the volumes in the area continue to grow, there is severe congestion at the ramps intersecting the frontage roads.”

Interchange issues

The intersection, which currently controls traffic with stop signs, is defined in the South Montgomery County Mobility Study as “severely over capacity” because traffic exceeds the roadway’s capacity, the road has unacceptable delays, unstable traffic flow, and stop-and-go conditions.

During a traffic count on the intersection in 2014, Robinson Road between I-45 and Hanna Road had a count of 16,170 commuters, while the capacity of the road is set at 17,800 vehicles per day, according to the Highway Capacity Manual.

Meanwhile, during a traffic count study in 2017, Woodlands Parkway between I-45 and Grogan’s Mill Road had a count of 63,859 commuters over 24 hours, while its capacity is set at 55,300 vehicles per day.

“The interchange at I-45 and Woodlands Parkway/Robinson Road needs to be improved, because the current interchange does not support the average daily traffic counts in the area,” TxDOT spokesperson Deidrea George said.

During a public meeting conducted in 2014 as part of the South Montgomery County Mobility Study, residents submitted comment cards about their local transportation concerns. Robinson Road received the third most comments of any south Montgomery County road with 203 comments, while Woodlands Parkway received the fifth most with 68 comments.

“Vehicles are unable to enter the frontage roads due to the high traffic volumes and high speeds on the frontage roads,” Beasley said. “Short spacing between the ramps create weaving conflicts with the frontage road [and] currently, the existing direct connectors serve the west side of I-45, but not the east side of I-45—[meaning] Oak Ridge North has limited access. Improving the interchange will improve access for all movements.”

In addition to traffic flow, local officials are also concerned about the safety of the intersection. According to the TxDOT’s Crash Records Information System, from 2010 to 2017, the Woodlands Parkway/Robinson Road stretch between Six Pines Drive and Hanna Road experienced a total of 382 crashes involving 890 vehicles and 1,227 people.

For comparison, during that time, the intersection of Research Forest Drive/Tamina Road—a similar east-west corridor in The Woodlands area with the same limits—experienced a total of 207 crashes involving 429 vehicles and 610 people.

“The Woodlands Parkway overpass feeds directly onto Robinson Road, which is the main street of Oak Ridge North,” City Manager Vicky Rudy said. “The overpass is in the city limits, [so] any improvements directly affect our community.”

A quick fix

Precinct 3 initially proposed a single-point urban interchange years ago to alleviate traffic at the intersection as a long-term solution. The project was included as one of the projects in the $280 million Montgomery County bond election approved by voters in November 2015.

However, upon learning that TxDOT was planning to initiate a potentially three-year planning and environmental linkage study this year, TxDOT advised the precinct to wait until the study was completed to determine the best long-term solution.

In the meantime, TxDOT officials said the county still must address the heavy traffic in the corridor with an interim project until the PEL study is completed, George said.

The most probable interim solution under consideration for the intersection is a diamond interchange, which would cost about $3 million, funded by Precinct 3 and Oak Ridge North, and which would take approximately 14 months to complete.

“A diamond traffic signal allows the interchange to function at a better level of service as TxDOT continues their evaluations of the I-45 corridor,” Beasley said. “This short-term improvement is cost-effective and will greatly benefit mobility in the area. A broader solution will be needed in the long-term.”

A diamond interchange is a road junction in which a freeway crosses a minor road. This junction has two traffic signals, one on each side of the freeway, which are synchronized, allowing for better traffic flow.

However, because this type of junction is most effective in areas of light traffic, implementation of a diamond interchange at this intersection would serve only as an interim solution until TxDOT and Precinct 3 can fund and construct a long-term solution, according to Beasley.

Beasley said a construction timeline on the interim solution has not been determined, because design on the project cannot begin until TxDOT gives Precinct 3 an advanced funding agreement—an accord between TxDOT and a local government entity to implement a transportation project.

Beasley said it is too early in the process to estimate when a diamond interchange could be feasible.

Down the road

The primary long-term solution under consideration for the intersection is a single-point urban interchange including U-turn lanes, which would cost $60 million. Precinct 3 would fund $3 million and TxDOT would submit the remaining $57 million. Construction on this project would take an estimated 24 months to complete, Beasley said.

“Oak Ridge North is happy with the design of this diamond interchange as proposed by Commissioner [James] Noack,” Rudy said. “The SPUI design may be appropriate many years down the road, but this design addresses current issues in real time and at a reasonable cost.”

A SPUI is similar to a diamond interchange, but has one traffic signal in the middle of the freeway, either on top or under the freeway bridge. With this design, vehicle delays related to signal operation are typically less than with the diamond interchange, Beasley said.

The junction design is most effective in areas that have heavy traffic, which drivers who travel the I-45 and Woodlands Parkway/Robinson Road interchange experience daily, Beasley said.

However, the SPUI project has not been approved, and a final decision will be determined by recommendations made in TxDOT’s PEL study. George said conducting a PEL study serves to minimize duplication of efforts, promote environmental stewardship, encourage public engagement and reduce delays in project implementation.

“The purpose of the I-45 PEL study is to conduct analysis and planning activities with resource agencies and the public in order to produce a transportation planning product that effectively serves the community’s transportation needs,” George said.

Phase I of the PEL study began in spring 2017 and is expected to be completed by summer 2018.

Phase 2 may follow if Phase 1 deems it necessary and could take an additional two years. With this timeline, a long-term recommendation could be anticipated by mid-2020.