Tag Archive for: bridge

FM1485: What’s Wrong With This Picture?

I took this picture on May 26, 2021. It shows TxDOT construction of the new State Highway 99 (Grand Parkway) next to FM1485 in New Caney. The picture looks northeast toward Colony Ridge in Liberty County. The East Fork of the San Jacinto River flows under both bridges toward Lake Houston on the right.

Looking east toward Colony Ridge across FM1485 and the East Fork. Water flows left to right.

Note the huge backup of water trying to get under the FM1485 bridge. Also note how much taller and wider the new bridge is compared to the old one.

How Much Rainfall Caused This?

Here is rainfall for the month of May as measured by the Harris County Flood Control District Gage at this location.

The Harris County Flood Warning System shows that the largest rainfall for the month was 2.28 inches TWO days before the photo. But the ground was clearly saturated from steady, moderate rains the week before.

The gage upstream at FM2090 shows slightly more rain. It reported 14 inches for the month instead of 11, but it received exactly 2.28 inches on the same day this gage did. While 2+ inches in a day is substantial, few in this part of the world would consider it excessive – especially since it was spread out over 5 hours.

Likewise, according to Atlas-14 standards, the rain that fell in the week before would qualify as a 1- to 2-year rain – notable, but not historic.

Note the 7-day rainfall totals in columns 1 and 2.

Submerged 41 Times in 32 years

And after consulting Harris County Flood Control District records, I learned that FM1485 has gone under water 41 times since 1990 – an average of 1.32 times per year.

The East Fork came out of its banks and flooded this area twice in the week before the picture was taken.

Rainfall data, road flooding frequency and the photo all suggest that a 1- to 2-year rain is enough to flood FM1485.

What Should a Roadway over a Major River Withstand?

Yet the TxDOT standard suggests that such minor arterials and bridges over a major river crossing be built to withstand 25- to 50-year floods. Oops!

Obviously TxDOT built a much higher road and a much wider, taller bridge for its new highway. The new one is approximately five times wider than the old one. Construction standards for major highways could account for that. But so could TxDOT’s experience with FM1485.

So What’s Going on Here?

Why did TxDOT make the new bridge so much wider and taller?

  • Did TxDOT just get the engineering wrong on the old bridge?
  • Did bridge standards change over time?
  • Do state highways have higher standards than farm-to-market roads?
  • Did Atlas-14 increase the risk?
  • Did upstream development, such as Colony Ridge, alter the hydraulics of the watershed when the developer paved over wetlands and deforested thousands of acres while providing little detention-pond capacity?
  • Did the mischaracterization of soil types in Colony Ridge lead to more runoff than anticipated?
  • All of the above?
  • Some of the above?

Jeff Lindner, Harris County’s meteorologist, cautions that, “Water surface elevations depend on many variables…rainfall patterns, intensity, soil conditions, water level in the river when the rain started, ect. It is usually difficult to compare events as no two are exactly alike. You really need a hydrological analysis of the location to determine the amount of run-off from that site into the river per an amount of rainfall.”

Good luck with that! More than six months after the Liberty County Attorney launched an investigation into Colony Ridge drainage reports, we still are waiting for answers.

Posted by Bob Rehak on 7/15/2021

1415 Days since Hurricane Harvey

The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.

Bridge over Tracks, Upstream Detention on Friday’s Commissioners Court Agenda

Two Kingwood-related items are on Harris County Commissioner’s Court agenda for this Friday.

#60 Recommendation to execute a Partnership Agreement with TXDoT for preliminary engineering and environmental review for a railroad grade separation on Hamblen Road, from Loop 494 to Laurel Springs Lane.

#83 Authorization to negotiate an interlocal agreement for a partnership project with the SJRA, Humble, and five utility districts for a feasibility study and conceptual design on the Spring Creek Watershed Flood Control Reservoirs.

Bridge over UP Tracks

The first item relates to the development of Precinct 4’s new Edgewater Park at 59 and the West Fork. Hamblen Road will be re-routed during park construction so that it connects with the first bridge over US59 north of the West Fork and Sorters-McClellan Road.

This would improve traffic flow and expand the development area of the 90-acre park that will serve as a key anchor park along the Spring Creek Greenway trail.
The current two-lane asphalt segment of Hamblen Road runs across the Union Pacific Railroad track through the middle of the proposed park. Plans include rerouting the new segment diagonally from Loop 494 at Sorters-McClellan Road to Laurel Springs Lane and upgrading it to a four-lane concrete with a bridge over the railroad track. The previous Hamblen Road segment could then be repurposed to serve park visitors. If approved, construction will not affect the park’s cypress ponds.

Tentative plans for a new Edgewater Park at Hamblen Road and Loop 494. The proposed bridge across the railroad would be part of the diagonal segment.

The bridge would also provide an evacuation route from Kingwood in the event of a railroad accident. UP plans to increase the length of its trains making a bridge more important than ever. In the event of a derailment, the longer trains (without the bridge) could block all Kingwood exits to US59.

Also, the current intersection is one of the most dangerous in Kingwood. Danny Sullivan, of Sullivan’s Automotive, says he tows vehicles almost daily from this stretch of road. There are a number of blind turns with people trying to cut across multiple lanes as traffic zooms north off the San Jacinto bridge.

Spring Creek Reservoirs: Feasibility Study, Conceptual Design

The second item arose out of the San Jacinto River Basin Master Drainage Study and a Spring Creek Siting Study conducted in parallel. This current project would study the feasibility of alternative locations and provide conceptual designs for one or more reservoirs.

Additional upstream detention is one of the three main legs of the Lake Houston Areas flood-reduction strategy. Upstream detention would reduce the inbound flow; dredging is restoring conveyance of the West Fork; and additional gates on the Lake Houston Dam will help eliminate backups.

Peak flows from various tributaries during Hurricane Harvey. Source: SJRA.

During Harvey, Spring Creek provided one third of the flow coming down the West Fork between Humble and Kingwood. To put that in perspective, that was as much as the peak release from Lake Conroe. Retaining even a portion of Spring Creek’s floodwater upstream would benefit people in Precinct 3 and Precinct 4 all across northern Harris County.

So even though this would be far upstream and not in our area, it still has the potential to reduce flooding significantly in the Lake Houston Area. And that’s very good news.

Thanks to Precinct 4 Commissioner Jack Cagle, Harris County Flood Control and their partners for pushing this project forward.

Posted by Bob Rehak on 2/24/2021

1275 Days since Hurricane Harvey

New Union Pacific Railroad Bridge over San Jacinto Will Have Wider Spans

Many readers have asked what the Union Pacific Railroad (UP) is doing to its bridge over the San Jacinto near US59. According to the Houston Chronicle, UP is widening the spans to reduce the potential for catastrophic damage in the event of another storm like Harvey.

If you have children or grandchildren that love trains, cranes and building things, you’ll want to share this post with them. It’s a real life example of a massive (re)construction project in the middle of difficult circumstances and a testament to the kind of brainpower and brawn that built this country.

A New Bridge Rises from the Old

These photos taken on Monday of this week (11.4.2019) illustrate how a new Union Pacific bridge is rising in the same place as the old one. With wider spans, the bridge will now also require different construction.

Wider concrete supports and a steel bed will replace the old tubular supports. UP constructed a temporary bridge next to the new bridge to hold the construction cranes.
This wide shot taken on 11/4/2019 shows how much wider the new spans are compared to the old.

Problems with Old Union Pacific Bridge

Back in 2017, the supports of the old bridge caught many trees swept downstream by Harvey. As you can see in these photos, the old bridge had two or three times the number of supports. David Seitzinger, a Kingwood resident, identified the supports and the trees they caught as a contributor to flooding in this analysis of water levels, flows and timing during Hurricane Harvey.

Photo from September 14, 2017. Harvey knocked out the old bridge. It took weeks to repair and shut down northbound rail traffic.
During Harvey, those old supports caught debris floating downstream that partially dammed the river and destroyed the railroad. Photo from UP report on flood.

A Marvel of Engineering Ingenuity

Current photo shows how the narrow spacing of supports for the temporary bridge are still catching debris floating downstream.
When complete, the bridge will border Harris County Precinct 4’s new Edgewater Park (lower right).
The wider spans should help protect the commercial areas south of the river from flooding.

This presentation explains the importance of railroads to the region’s economy and damage that Harvey did to UP.

The progress of this construction is another encouraging sign of recovery from Harvey.

Posted by Bob Rehak on 11/6/2019 with thanks to the Union Pacific Railroad

799 Days after Hurricane Harvey