Attachment_06_StructureSummaries.xlsx

XLSX spreadsheet 35 KB Posted Mar 16, 2026

Attached to: Sam Houston Trail Bridge Replacement Federal contract opportunity
Solicitation number: 127EAV26R0009
Issued by: Department of Agriculture Forest Service R3-Southwestern Region

About this file

Written by GovTribe AI · Mar 16, 2026

This is a structural assessment and recommendations document for 18 trail bridges located on the Sam Houston National Forest Multi-Use Trail west of New Waverly, Texas. The file provides detailed field survey data including geographic coordinates, structural conditions, dimensional specifications, geomorphological characteristics, and engineering recommendations for each bridge site.

The document details specific conditions for each of the 18 bridges, noting issues such as abutment failures, bank erosion, scour undermining, insufficient clear heights for flood flows, timber deterioration, and settlement problems. Key dimensions recorded include overall structure length (ranging from 20 to 50 feet), structure width (6 to 8 feet), clear height (3.1 to 12 feet), active channel width, and floodplain width. Geomorphological analysis identifies soil types (primarily fine sand, mottled clay, and various gravel compositions), channel characteristics (entrenched, meandering, braiding), and stability concerns (vertical and lateral instability, erosion, headcut migration). Engineering recommendations for each site include specific interventions such as relocating crossings upstream or downstream (ranging from 30 to 300 feet), constructing new trail bridges with increased span lengths (30 to 65 feet), installing deep foundations, hardening trail approaches, removing debris, and in some cases implementing stream mitigation measures. The assessment provides the technical foundation for the design and construction phases outlined in the federal solicitation for full replacement of crossing infrastructure across the 18 sites.

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Other files for this federal contract opportunity

Other files attached to Sam Houston Trail Bridge Replacement, newest first.
File	Type	Posted
127EAV26R0009 Pre Bid Meeting Sign In.pdf	PDF	May 9, 2026
trails 5-5-25.pdf	PDF	Apr 10, 2026
Amendment 127EAV26R0009 P00002.pdf	PDF	Apr 10, 2026
127EAV26R0009 Responses to Questions.pdf	PDF	Apr 10, 2026
127EAV26R0009 P0001 3.26.pdf	PDF	Mar 26, 2026
Attachment_04_VicinityMaps.pdf	PDF	Mar 16, 2026
Attachment_03_SOI.xlsx	XLSX spreadsheet	Mar 16, 2026
127EAV26R0009 Sam Houston Trail Bridge Replacement 3.16.pdf	PDF	Mar 16, 2026

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Abbreviations

Abbreviations Used
US	Upstream
DS	Downstream
NOB	Not Observed
DNE	Does Not Exist
A1	Abutment 1 (flow from right)
A2	Abutment 2 (flow from left)
TB	Trail Bridge

Overview

Overview
Bridge No. or Name	Trail No. & Name	X	Y	Location Overview
1	NFST 833 Lake Loop	-95.54660354	30.52203417	Pre-storm superstructure damage from fallen tree. Debris evident in truss members, appears to have nearly overtopped.
1 or C-57	NFST 871 NWCC- North Loop	-95.52234993	30.65666786	Bridge failure @ A2. Helical piers reinforce both abutment backwalls, but significant bank slump caused bridge to collapse further @ A2.
10	NFST 833 Lake Loop	-95.59096004	30.53388075	Railings in poor condition but otherwise bridge functional. Towards end of design life.
11	NFST 833 Lake Loop	-95.59127634	30.54405386	Existing bridge undermined @ A2. Stream is significantly entrenched and causing lateral and vertical instability of banks.
12	NFST 833 Lake Loop	-95.58933837	30.54660601	Fair condition structure with minor bank instability due to trail drainage impacting substructure.
13	NFST 830 Zebra	-95.58966674	30.55119921	In-service FRP spanning massive channel in significant floodplain. Sandy bottom terrain. Significant erosion@ A1 but not yet undermined. Overtopped at some point. Possibly due to debris damming downstream?
16	NFST 831 Fern	-95.56545268	30.5458509	Severe vertical instability. A1-US failing. A2 in fair condition. Banks near vertical both US & DS.
17	NFST 834 YCC	-95.57121798	30.56036165	A1 failure from trail drainage. Insufficient clear height for high flow.
18	NFST 834 YCC	-95.57100916	30.55958925	Heavy flooding with A1 undermined and collapsed. Past retrofits unsuccessful, possible migration of stream further towards A1.
19	NFST 834 YCC	-95.56534734	30.5481487	Timber bridge towards end of service life. A1 bearing on a combination of pavers, fleximat, and curbs. A2 on timber sill. Vertical instability evident in channel.
23	NFST 836 Boyscout	-95.54369822	30.54674385	A1 and approach @ A1 failure with significant settlement. Woody debris deposit DS and headcut approaching crossing. Bridge super good condition.
24	NFST 836 Boyscout	-95.54304855	30.53606042	Timber bridge in sandy low gradient valley. Overtopped and significantly settled at A2. Extensive floodplain. Large meander just downstream.
37	NFST 844 String	-95.66546967	30.54563732	In-service timber bridge at end of service life. Single main span plus 2 approach spans. Apparent settlement @ both approaches but especially A2.
38	NFST 844 String	-95.66617106	30.5470246	In-service timber bridge misaligned and settled due to bank erosion.
39	NFST 844 String	-95.6717591	30.554269	In service timber bridge with insufficient span. Settlement at both approaches.
4	NFST 833 Lake Loop	-95.55318895	30.51732354	Wide floodplain in valley with multiple drainage channels. Primary structure substructure failure due to location in a stream curve.
6	NFST 833 Lake Loop	-95.56059841	30.51684016	Existing structure overtopped and carried downstream.
800.1192	NFST 800 LSHT- Lone Star	-95.6760997	30.52103243	Log stringer bridge set on piles spanning large channel. Banks show signs of overflowing recently but no apparent impacts to structure.
8-A	NFST 833 Lake Loop	-95.58433581	30.52502769	Bridge in low gradient valley, overtopped with flood flows and debris and washed slightly downstream.
9	NFST 833 Lake Loop	-95.58849274	30.53381344	Bridge in low gradient valley overtopped with flood flows and debris.
Cagle Bridge	NFST 825 Cagle Loop	-95.5912751	30.52387241	2-span bridge with scour due to constrained channel. Failure of retrofit sheetpile protection.

Key Dimensions

Key Dimensions (in Ft.)
Bridge No. or Name	Overall Structure Length	Structure Width	Clear Height	Active Channel Width	Flood Plain Width
1	45	6	8.3	23	0
10	20	6	3.5	16	35
11	20	8	18	10 entrenched	35 top of banks
12	40	6	7.5	20	30
13	50	8	10.3	0	0
16	35	8	12	0	0
17	30	7	7	13	0
18	30	7	12	17	44
19	20	6	6.25	13	0
23	20	7	3.1	10	10
24	20	6	3.3	15	45
37	20	6	7.5	20	0
38	20	6	6	25	0
39	20	6	7.5	21	0
4	20	0	0	9	9
6	0	0	0	21	38
8-A	20	6	0	20	0
9	0	0	0	40	0

Geomorphology Geomorphology

	Bridge No. or Name	Channel Characteristics	Channel
Concerns	Soil

Description

1	Well-established channel with isolated lateral instability. Curve with bank erosion 125' US. Heavily vegetated.	Progressing bank erosion at A1- US possible. In extensive floodplain.	Fine sand.
1 or C-57	Significant instability both laterally and vertically. Choked with debris from storm events and mass wasting of banks.	Unknown at what width banks will stabilize. A1 located 100' south of private land boundary so no option to reroute US of existing instability. Increased runoff from surrounding urban development likely a major contributing factor. Bank instability extends well beyond bankfull or floodplain widths.	Mixture of organics, clean clay, and sandy deposits.
10	Meandering, low velocity lake tributary in sandy bottom. Lake possibly backs up to this point.	Backflooding from lake. Varying aggradation and degradation. Significant vertical instability.	Predominantly fine sand.
11	Entrenched with headcut migrating US. Unstable banks.	Headcut has destabilized banks and further migration within cross section is expected. Banks will find new angle of repose as stream reacts.	Mottled clay.
12	Well-defined overall. Some minor lateral and vertical movement.	None	Mottled clay with fine sand. Some pebbles.
13	Floodplain is hundreds of feet wide. Channel: incised. Laterally and vertically unstable. Scour hole between large magnolia and A1-DS. Bank particularly unstable @ A1.	Floodplain. Significant flow potential. Scour @ A1.	Fine sand.
16	Significant vertical instability that has not yet reached equilibrium. Original headcut approx. 100' US. Banks near vertical.	Vertical instability, bank stability.	Primarily clay with some fine sand and gravel.
17	Significantly incised. Minor vertical instability. Exposed roots on banks and root ladders typical.	Continued erosion @ A1.	NOB. Suspect mottled clay with sandy and gravelly deposits.
18	Note due to steepness of channel, active channel width recorded here is actually true bankfull. Steep-banked, well-vegetated, well defined. Signs of natural bank instability (slumping).	Bank instability (slumping). Meandering and significantly entrenched.	Mottled clay with some sandy and gravely deposits.
19	Significantly incised, meandering channel with steep banks of mottled clay. Heavy vegetation.	Vertical instability leading to widening of channel at crossing.	Mottled clay and fine sand deposits
23	Significant lateral and vertical instability, especially at crossing. Heavy woody debris deposit along banks and in stream. Headcut 40' DS.	Damming from loose debris. Instability. Trail drainage.	Silty, fine, sandy soil underlain by mottled clay and rounded gravel (1"-).
24	Moderate lateral and vertical instability. Meandering stream in large floodplain area.	Lateral instability and soil type.	Riffled sand in stream bed underlain by some mottled clay and subangular gravel (2"-).
37	Lateral and vertical instability evident. Braiding potential at bridge due to trees along banks. Blank slump evident in many locations US and DS.	Hummocky banks. Significant overall instability.	Sandy clay with gravel (1"-) in stream bed.
38	Vertically unstable but moderately laterally stable.	Vertical instability.	Sandy, silty clay with some gravel in stream bed.
39	Hummocky banks. Moderate vertical and lateral instability.	Overall channel instability.	Sandy, silty clay.
4	Well-defined primary channel in extensive floodplain with secondary channel(s) evident during high flows.	Erosive material due to flood plain deposition. Secondary channels require additional consideration.	Sand underlain by mottled clay. Heavy veg along primary channel banks.
6	Some minor channel instability due to damaging storms but overall healthy floodplain.	Channel itself is healthy overall. Former bridge was likely undersized. Slight lateral instability.	Mottled clay and sand.
800.1192	Wide channel in sandy bottom. Some vertical and lateral instability.	In floodplain. Likely frequent overtopping of banks.	Fine sand.
8-A	Well-defined, low angle sandy channel in delta. May be a newer channel with old channel serving as flood overflow just to the left. In delta area prone to flooding and possible backflooding from lake.	Flooding and backflooding. In flood plain.	Depositional zone. Primarily fine sand.
9	Wide floodplain w/ braiding channel type, low gradient, possible backwater effects from lake nearby.	Large floodplain. Future lateral instability and structure overtopping likely.	Depositional zone. Fine sand.
Cagle Bridge	Incised and entrenched with slight lateral movement. Meandering typical. Densely vegetated banks.	Constricted by abutments.	Mottled clay and sand.

Recommendations

Recommendations
Bridge No. or Name	For Stream	For Structure	For Trail/Alignment	Location- Alternative Crossing
1	None	50' TB with increased clear height, deep foundations, minimally elevated approach spans to accommodate floodplain.	Hardened approaches and consider approach spans.
1 or C-57	None.	Options either very long structure or low-tech crossing with routine maintenance. High tech will require significant investment and geotechnical evaluation. Due to nature of trail use, building switchbacks to a low water crossing is recommended until channel shows evidence of stabilizing. Be conscientious that further disturbance is likely to have high consequences.	None. If high-tech solution selected, match approaches to new alignment.
10	None	Replace with 60' boardwalk system and deep foundations designed to overtop. Elevated on approaches to accommodate floodplain.	Hardened approaches.
11	Entrenched channel will widen as stream stabilizes. Mitigations likely not feasible.	Reroute 220' upstream above headcut with shorter TB or ~300' downstream where banks have stabilized with longer TB.	Reroute trail 220' US. Some tread hardening may be necessary due to small ephemeral draws.	220' US
12	None	40' existing. Proposed 50' TB, additional length located beyond existing A2. Deep Foundations.	Improve trail drainage at approaches, especially @ A2.
13	Remove large magnolia to save structure at either current or proposed location.	Highly unstable banks, A1 undermined, relocate 40' DS with deep foundations and existing structure or new min. 50' TB	Hardened approaches.
16	None.	Highly unstable, similar to #11. Relocate 100' US (200' would be better) with deep foundations and existing 30' FRP TB.	Hardened approaches. Potential realignment if bridge relocated.	200' US
17	None.	30' existing, 40' proposed TB shifted towards A1 approach. Elevate for clear height and approaches to accommodate floodplain.	Improved trail drainage and hardened approaches. Slight realignment of trail approach @ A2 (currently tight curve).
18	None	Reroute upstream 40', away from DS curve. 60-65' TB on deep foundations, maximize clear height in constricted channel.	Slight 40' reroute to new bridge location. Harden approaches.
19	Remove fallen pavers and fleximat.	20' existing timber TB. Vertical instability with fleximat, pavers, curbs all cobbled together. Replace with 30' TB on deep foundations.	Hardened approaches.
23	Remove woody debris from channel 100' US and DS. Install log/rock vein DS to prevent further mobilization of headcut. Harden drain dip and drain-dip-caused side channel/leadout ditch from trail above crossing. Harden 5' above trail all the way to stream bed.	20' existing, A1 failure and DS headcut approaching. Relocate 80' upstream, 35-40' TB with deep foundations.	See note for stream recs.	80' US
24	None.	20 ex, approaching end of service life. 30' proposed (boardwalk/TB). Standard abutment with anchor.	Relocate crossing approximately 50' US to avoid meander. Hardened approaches.	50' US
37	None	20' existing. Very unstable banks, 45'-50' TB proposed with deep foundations.	Improve drainage. Hardened approaches.
38	None	20' with 5' approach spans existing. Unstable banks, 40' TB proposed with deep foundations.	Hardened approaches.
39	None.	20' with 5' approach spans existing. Unstable banks, 40' TB proposed with deep foundations.	Hardened approaches. Slight realignment of trail @ A2-US (5' US) to make more perpendicular to stream.
4	None	Realign trail US, 20-30' TB on deep foundations, 130' hardened approaches & secondary channel (4a) on east.	Extensive tread hardening as part of secondary channel (Designated 4a).	115' US
6	None.	Hardened crossing with extended hardened approaches (or 65' TB on deep foundations)	Standard drainage features on approaches.
800.1192	None.	TB has been reset and anchored. No obvious issues. Replace if desired with 35' truss on deep foundations and approach spans or stairs.	None.
8-A	None.	50-60' boardwalk system over primary channel, additional hardening to secondary channel	Hardened approaches, focusing especially on overflow stream to the left where pavers currently exist and function well.
9	None.	Relocate crossing 30' downstream with boardwalk system and deep foundations designed to overtop.	Relocate 30' DS. Hardened approaches.	30' DS
Cagle Bridge	None.	30' existing, 45' proposed TB. Standard abutments likely feasible.	Hardened rolling dips on both approaches.

File details come from the government source that posted it. Updated Mar 16, 2026.