Steve Boggs: Diverging diamond design coming to Highway 84 corridor

The Texas Department of Transportation unveiled its plans to improve the Highway 84 corridor coming into Waco from the west last week at a public meeting in Woodway. There were the obvious crowd-pleasing projects in the overall plan, like a bridge over New Road at Franklin Avenue — eliminating, or at least alleviating, what has to be Waco’s No. 1 traffic hassle — as well as the proposed flyovers at Highway 6 and Highway 84. Those are needed improvements, and widely popular among Central Texas drivers.

It uses a crisscross pattern at both entrances to the intersection, with traffic flowing on the opposite sides of the traditional traffic pattern. Synchronized traffic lights control how traffic flows through the intersection, eliminating hard left-hand turns where possible. If you’ve driven through the Hewitt/Estates intersection, you know it’s fairly narrow, and the left onto Hewitt Drive from the westbound Highway 84 off-ramp is sharp and sometimes harrowing.

The new design incorporates the dynamics of the Texas turnaround without having to build a new bridge, a major selling point for a chronically underfunded state agency trying to stretch construction dollars as far as it can. A left onto Hewitt Drive can become a left onto the eastbound Highway 84 frontage road, much like it is now, but without having to wait for a left green arrow. The same dynamic exists from the other direction. But unlike the Highway 84 and Highway 6 intersection, no new Texas turnaround lanes and bridges will be added at the Hewitt/Estates intersection. Or, to be more specific, none are included in the plans at this point. There is a second community input meeting on the corridor project this summer.

Texas turnaround lanes are a fixture in most new construction, but their cost is making TxDOT more judicious in implementing them. The $46 million mall-to-mall effort incorporates them, but that is basically the point of the project in building continuous frontage roads from Bagby Avenue to Waco Drive along Highway 6.

While the traffic pattern within the diverging diamond design itself isn’t too drastically different, there will be a much larger impact on local traffic adjacent to the intersection. For starters, the frontage road at the top of the Hewitt Drive off-ramp from Highway 84 will be turn only — onto Hewitt Drive or toward Estates Drive — on both sides. Motorists will no longer be able to go straight through the intersection and get in line at Shipley Do-Nuts at the Crossroads West shopping center or hang a quick right into the Walgreens parking lot. And H-E-B shoppers will no longer be able to turn left onto Hewitt Drive from Oak Creek Drive, where the majority of cars enter and exit the busy grocery store now. Admittedly, that’s a tough left to come by on most days.

Traffic engineers who came up with this design expect pushback, but swear their diverging diamond design moves more traffic efficiently than what is in place now. I find that easy to believe. Afternoon rush hour on Hewitt Drive is brutal at times, and it’s all fed by that intersection. Who hasn’t sat through three traffic light cycles trying to make a left onto Hewitt Drive?

The Waco Metropolitan Planning Organization’s 2010 count put Hewitt Drive traffic at 30,000 cars a day.

The diverging diamond design will also effectively prevent traffic from getting across Hewitt Drive in the area of the busy intersection. With no left available from Oak Creek onto Hewitt Drive, it will force drivers to the right, and in search of a U-turn spot — presumably at Old McGregor Road, trying to get back to Highway 84, or into the surrounding neighborhoods. As a cheat, try driving behind H-E-B and hitting the frontage road from there. More on that below.

TxDOT has adopted longer on- and off-ramps in the name of safety in its newer designs. The rebuilt I-35 through downtown Waco employs this strategy. It’s fine for through traffic, but it doesn’t prioritize local connections, nor does it merge well with previous highway designs. That’s the main reason why the final section of I-35 should be a top priority — the New Road intersection is a mess and the unimproved stretch from 12th Street to South Loop 340 is where Waco is growing the fastest. In the Highway 84 corridor project the eastbound off-ramp to Texas Central Parkway is being pushed back beyond Hewitt/Estates drives. In fact, the two intersections will share the same off-ramp, with Texas Central traffic utilizing a new frontage road below the Hewitt/Estates bridge to get to its destination. Access to the under-the-bridge lane is not available from the parking lot in front of H-E-B. Those exits put you on the frontage road that merges at the diverging diamond. To reach the lower lane below the bridge, you’ll have to go behind H-E-B, or make your way back to Sunn Drive.

Local commuters will have to adjust to this new alignment, and it will take some time to find the cheats that keep them out of traffic. Expect Old McGregor Road to get a lot busier east of Hewitt Drive. It’s going to be a turnaround opportunity for some, and an increasingly important outlet utilized in getting to Texas Central Parkway.

Most commuters into town from the southern suburbs, myself included, are willing to take a wait-and-see approach when it comes to the diverging diamond design. As long as we can skip the wait at New Road on our way into work, we’re good. If TxDOT engineers can entice motorists to actually reach the speed limit on Hewitt Drive, they can roll out whatever design they want, as far as I’m concerned.

In the meantime, let’s discuss an overpass at Chapel/Imperial, shall we?