TxDOT Item 247 Spec

Texas Road Base Calculator — TxDOT Specifications

Q: What is TxDOT Item 247 Flexible Base?

TxDOT Item 247 is the official Texas Department of Transportation specification for crushed stone and caliche road bases used under highways, commercial parking lots, and driveways.

Q: What is the difference between TxDOT Grade 1 and Grade 2 base?

Grade 1 is the highest specification, requiring higher compressive shear strength (Triaxial Class 1.0) and lower plasticity (PI < 10) for heavy highway traffic. Grade 2 is the standard commercial specification used for residential driveways and city roads.

Calculate Texas Department of Transportation (TxDOT Item 247) flexible road base tonnage, cubic yards, and commercial truck deliveries across Grade 1, Grade 2, and Grade 3 limestone and caliche specifications.

ASTM / AASHTO Verified

Compaction & Waste Factors Included

Dump Truck Capacity Dispatcher

Imperial Standard (yd³ & Tons)

Texas TxDOT Item 247 Flexible Base Calculator

Calculate Type A Limestone, Type C Caliche & Type D RCA with Texas Belly Dump / End Dump freight logistics

TxDOT Item 247

1. Texas Project Dimensions & Base Depth

Length (Feet)

Width (Feet)

Depth (Inches)

Texas Presets:

2. TxDOT Item 247 Flexible Base Type

Texas Freight & Hauling Logistics: Belly Dump Windrowing

Quarry Haul Radius

Hauling Truck Type

TxDOT Flexible Base Output

Total Texas Flexible Base Required

181.8

Tons (approx. 8 Belly Dump Loads)

Compacted In-Place Vol 79.0 yd³ 2,133 cu ft in place

Loose Delivery Volume 98.8 yd³ +25% compaction factor

Water Required (OMC) 2,990 Gal 8.5% water for cementing

Estimated Total Cost $5,825 Material + Freight

TxDOT Construction Guidelines:

Windrow material with belly dumps and blade to 4" loose lifts.
Apply water thoroughly with spray bar to achieve 100% Tex-114-E.
Compact with sheepsfoot roller followed by pneumatic rubber tires.
Cut a 3% crown (3/8" per foot) to prevent rain puddling.

TxDOT Highway Specification

TxDOT Item 247 Flexible Base (Grade 1, 2, 3) Engineering Specifications

TxDOT Standard Specifications Item 247

TxDOT Specification Type A (Crushed Stone) | Type D (Crushed Caliche)

Typical Depth 6.0" (Driveways) | 8.0"–12.0" (Highway Subgrade)

Target Proctor 100% Tex-113-E Modified Compaction

Moisture Target Test ±1.5% of Optimum Moisture (Tex-113-E)

Triaxial Class Class 1.0 (Grade 1) | Class 1.5–2.3 (Grade 2)

Compacted Dry Density 138 lb/ft³ (2,210 kg/m³)

Weight per Volume 1.86 Tons / yd³

Plasticity Index PI < 10 (Grade 1/2) | PI < 12 (Grade 3)

Texas Civil Engineering Math

How to Calculate Texas Flexible Base Tonnage, Cubic Yards & Belly Dump Loads

Mathematical equations for TxDOT flexible base volume conversions, compaction shrinkage (+18–22%), and Texas belly dump load division.

1 Surface Area

Area Geometry

Area = Length (ft) × Width (ft)

Determine the square footprint of your driveway, patio, slab, or pad. For curved shapes, break the area into offset rectangles.

2 In-Place Volume

Compact Volume

Vol (yd³) = (Area × Depth_in ÷ 12) ÷ 27

Convert design depth to volumetric units. This represents the final solid in-place compacted volume required after rolling.

3 Compaction Loss

Gross Loose Volume

Loose Vol = Compact Vol × (1 + 20%)

Quarries sell aggregate in its loose, aerated state. Adding 20% accounts for void compression under mechanical vibration.

4 Weight & Ordering

Quarry Tonnage

Tons = Vol (yd³) × 1.82 × 1.05 Waste

Convert volume to bulk weight using dense-graded stone density, adding 5% for site grading tolerance and edge bevel waste.

Real-World Numerical Example

Worked Calculation: 1,000 sq ft Driveway at 6" Compacted Depth

Target Material: Texas Road Base Calculator

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Step 1 — Calculate In-Place Volume:

1,000 sq ft × (6 ÷ 12 ft) = 500 cu ft ÷ 27 = 18.52 cubic yards

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Step 2 — Apply +20% Compaction & +5% Waste:

18.52 yd³ × 1.20 (shrinkage) × 1.05 (waste) = 22.95 loose cubic yards

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Step 3 — Multiply by Quarry Bulk Density (1.86 Tons / yd³):

18.52 compacted yd³ × 1.24 combined factor × 1.82 Tons/yd³ = 41.8 Tons total order weight

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Step 4 — Calculate Hauling & Estimated Material Cost:

42 Tons ÷ 20-ton Tri-Axle = 3 Dump Truck Loads | Quarry Stone Cost: ~$1218

Order Sheet Summary

Total Order Weight: 41.8 Tons

Loose Volume: 23.0 yd³

Truckloads Required: 3 Tri-Axle Loads

Estimated Quarry Price: $1218

Tex-110-E Particle Size Test

TxDOT Item 247 Flexible Base Particle Size Distribution & Sieve Analysis

Laboratory sieve curve analysis for TxDOT Item 247 Grade 1 and Grade 2 flexible base showing distribution from 1-3/4" down to #200 fines.

Standard Sieve Size % Passing (Design Target)

1 1-3/4" (45.0 mm)

Spec: 100% 100%

2 7/8" (22.4 mm)

Spec: 65% – 90% 78%

3 3/8" (9.5 mm)

Spec: 40% – 70% 55%

4 No. 4 (4.75 mm)

Spec: 25% – 55% 40%

5 No. 40 (425 µm)

Spec: 15% – 30% 22%

6 No. 200 (75 µm)

Spec: 4% – 12% 7%

Selected Sieve Analysis Spec: 100%

1-3/4" (45.0 mm)

Target Percent Passing

100%

Geotechnical Function:

TxDOT Item 247 top size.

Dense-Grading Principle: Continuous particle distribution from top size to sub-75µm fines locks stone voids, reducing empty space from 35% to <12% under vibration.

Civil Estimating & Geotechnical Engineering Review

Peer-Verified

Formulas, density conversions, and lift recommendations are modeled after AASHTO M147 (Materials for Aggregate and Soil-Aggregate Subbase) and ASTM C33/D2922 standards. Reviewed by licensed civil engineers and heavy highway earthwork estimators.

• AASHTO M147 Compliant • ASTM C136 Sieve Analysis • ASTM D698 / D1557 Proctor Compaction

Texas Pavement Cross-Section

Texas Highway & Driveway Flexible Base Structural Layer Profile

Cross-sectional structural profile for Texas roadways over high-plasticity Texas Blackland Prairie expansive clay soils.

TxDOT Two-Course Surface Treatment

AC-15P Asphalt + Grade 4 Aggregate

0.75" – 1.0" Surface Seal

TxDOT Item 247 Flexible Base (Top Lift)

Crushed Limestone Grade 1/2

3.5" Compacted 100% Tex-113-E

TxDOT Item 247 Flexible Base (Bottom Lift)

Crushed Limestone Grade 1/2

3.5" Compacted 100% Tex-113-E

Class 1 Geotextile Membrane

Non-Woven Polypropylene Fabric

6 oz / yd² Subgrade Stabilizer

Lime-Stabilized Texas Clay Subgrade

Native Clay + 4% Hydrated Lime

6.0" – 8.0" 95% Tex-114-E

Layer Inspection 0.75" – 1.0"

TxDOT Two-Course Surface Treatment

AC-15P Asphalt + Grade 4 Aggregate

Compaction Standard: Surface Seal

Engineering Function & Placement:

Waterproof seal protecting flexible base.

Subgrade Rule: Never place aggregate over uncompacted or organic subsoil. Proof-roll native soil with a loaded dump truck before laying the geotextile separation membrane.

Structural Depth Schedules

TxDOT Flexible Base Thickness Schedules for High-PI Texas Blackland Clays

Recommended layer thicknesses for Texas ranch roads, residential driveways, oilfield pads, and highway sub-bases over swelling clay.

Structural Depth & Lift Schedule by Use Case

Recommended compacted thickness and placement lift sequences

AASHTO / ICPI Guidelines

Project Application	Recommended Depth	Lift Sequence	Target Compaction	Engineering Note
Pedestrian Walkways & Garden Paths	3.0 – 4.0 inches	1 Lift (3–4" loose)	95% Standard Proctor	Edge restraints recommended to prevent foot-traffic gravel scatter. Geotextile optional on firm soil.
Paver Patio & Outdoor Living Slabs	4.0 – 6.0 inches	1–2 Lifts (3" compacted each)	98% Modified Proctor	Top with 1.0 inch of ASTM C33 concrete bedding sand. Screed flat without compacting sand prior to paver placement.
Light Residential Driveways (Cars & SUVs)	6.0 inches	2 Lifts (3" compacted each)	98% Modified Proctor	Crown driveway 1/4" per foot from center to edges. Install 4–6 oz non-woven geotextile over clay subgrades.
Heavy Vehicle, RV & Boat Storage Pads	8.0 – 10.0 inches	3 Lifts (3" compacted each)	100% Modified Proctor	Over-excavate pad footprint 12 inches beyond parked tire footprint for lateral edge confinement.
Shed, Pole Barn & Equipment Foundations	5.0 – 6.0 inches	2 Lifts (3" compacted each)	98% Modified Proctor	Extend gravel pad 12–18 inches beyond shed drip edge to capture roof runoff without foundation erosion.
Commercial Parking Lots & Highway Sub-Base	10.0 – 14.0 inches	3–4 Lifts (3–4" compacted each)	100% AASHTO T180	Requires proof-roll QA testing with loaded dump truck (20-ton axle) and nuclear density gauge verification.

Geotechnical Subgrade Rule

Subgrade Soil Adjustments & Geotextile Requirements

ASTM D1883 Subgrade Evaluation

CBR > 15%

Dense Gravel / Coarse Sand Subgrade

Base Depth Mod: Standard design depth (0" added)

Geotextile: Optional / Not Required

CBR 6% – 10%

Firm Silt / Sandy Loam Subgrade

Base Depth Mod: +1.0 to +2.0 inches extra base

Geotextile: Recommended (4 oz Fabric)

CBR 2% – 4%

Expansive Clay / Black Cotton Soil

Base Depth Mod: +2.0 to +4.0 inches extra base

Geotextile: Mandatory (6 oz Non-Woven Geotextile)

CBR < 2%

Wet Saturated / Organic Muck Subgrade

Base Depth Mod: +4.0" to +6.0" Base + 4" Surge Stone

Geotextile: Mandatory (Class 1 Geotextile + Biaxial Geogrid)

TxDOT Tex-113-E Compaction Standard

TxDOT Tex-113-E Compaction Testing, Moisture Conditioning & Triaxial Class

Texas compaction simulator demonstrating how 6.5% OMC achieves 100% Tex-113-E density and Triaxial Class 1.0 structural strength.

1. Loose Lift Thickness (Inches) 4.0" Loose Lift

2.0" (Hand Tamper) 4.0" (Max Plate Compactor) 6.0" (Small Roller) 8.0" (Heavy 5-Ton Roller)

2. Moisture Content (% by Dry Weight) 6.5% OMC (Optimum)

2% (Too Dry / Friction) 6.5% (Optimum Peak) 12% (Over-Saturated / Pumping)

Compaction Result: Optimal 98% Proctor

At 6.5% moisture and 4.0" loose lift, stone dust particles lubricate under vibration, packing completely into rock voids without excess pore water pressure.

Field Compaction Parameters

Target Proctor Density: 100% Tex-113-E Modified Compaction

Compaction Shrinkage: +20% extra loose volume

Water Dosage per 100 sq ft: ~18 Gallons

Compactor Passes: 6 to 8 passes with heavy vibratory compactor or pneumatic roller

Recommended Machinery:

Heavy 5-ton vibratory steel roller or 15-ton pneumatic multi-tire roller.

Texas Hauling Logistics

Texas End Dump, Belly Dump & Tandem Hauling Logistics

Calculate Texas truckload capacities across tandem axle dumps (14–16 tons), tri-axle end dumps (18–22 tons), and belly dumps (24–26 tons).

Selected Vehicle Specification

Tri-Axle Commercial Dump Truck

Most economical rate per ton (Contractor standard)

Payload Weight 18–22 Tons

Payload Volume 11–13.5 yd³

Clear Gate Width 12 ft Min

Overhead Wire Clear 24 ft Raised

Site Access Rule: A loaded tri-axle weighs ~65,000 lbs (32.5 tons gross). Ensure driveway culverts and bridges are rated for this axle weight before scheduling delivery.

Delivery Site Checklist:

Check overhead tree branches and power/phone wires.

Mark septic tanks, leach fields, and sprinkler heads.

Never dump on a cross-slope >8% (dump bed tip-over risk).

Have driver tailgate-spread stone in a thin pass to save shovel time.

Budget & Labor Estimator

Texas Flexible Base Material Cost, Freight & Contractor Estimator

Estimate Texas quarry pricing ($22–$36/ton), rural mileage hauling fees, motor grader grading, and turnkey contractor installation budgets.

1. Total Project Area (Square Feet) 1,000 sq ft

100 sq ft (Walkway) 600 sq ft (2-Car Pad) 1,200 sq ft (Driveway) 10,000 sq ft (Acre Lane)

2. Material Quarry Price ($ / Ton) $29 / Ton

$15/Ton (Pit Direct Caliche/RCA) $29/Ton (Avg Crusher Run) $75/Ton (Imported Granite)

Equipment & Hauling Options:

Delivery Fee (per truckload)

Equipment Rental

DIY vs Contractor Cost Comparison

DIY Total Cost (Materials + Rental + Delivery)

$1,444

~$1.44 per square foot

Contractor Turnkey Cost (Excavation + Install + Base)

$5,500

~$5.50 per square foot ($4.50 – $7.50 / sq ft range)

DIY Labor Savings: You save approximately $4,056 in contractor excavation and installation labor on this project.

TxDOT Grade Comparison Matrix

TxDOT Item 247 Grade 1 vs Grade 2 vs Grade 3 vs Texas Caliche Comparison

Direct comparison between TxDOT Grade 1 (high strength), Grade 2 (standard road), Grade 3 (commercial/driveway), and pit caliche.

Material Type	CBR Bearing Ratio	Compacted Density	Permeability	Avg Cost / Ton	Recommended Application
TxDOT Item 247 Grade 1 (Limestone) This Page	Triaxial Class 1.0 (CBR > 100%)	138 lb/ft³	Low	$28 – $36	State highways, heavy commercial aprons, heavy truck pads
TxDOT Item 247 Grade 2 (Commercial)	Triaxial Class 1.5–2.3	136 lb/ft³	Low	$24 – $32	City streets, residential driveways, parking lots
Texas Pit Caliche (Type D)	Triaxial Class 2.3–3.0	132 lb/ft³	Impermeable	$16 – $24	Ranch roads, oilfield pads, budget rural lanes
Recycled Concrete Base (Type E)	Triaxial Class 1.5	126 lb/ft³	Low-Moderate	$18 – $26	Industrial staging yards, budget driveway foundations

Quality Assurance & Failure Prevention

TxDOT Quality Assurance: Triaxial Compressive Strength, Tex-110-E & Proof-Rolling

Verification methods for Tex-117-E Triaxial classification, Tex-106-E plasticity index (< 10), and proof-rolling with heavy water trucks.

4 Contractor Field Tests to Verify Density (Without Nuclear Gauge)

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Hand-Squeeze Moisture Test

Field Test

Target: Verify Optimum Moisture Content (OMC) before rolling

Execution Procedure: Grab a handful of spread base material and squeeze tightly in a closed fist. Open your hand.

Pass: Aggregate forms a dense, solid clump with zero crumbling and leaves palm damp without dripping liquid. Fail: Crumbles to dust (too dry) or oozes watery mud (too wet).

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Proof-Roll Axle Deflection Test

Field Test

Target: Identify weak subgrade pockets and verify base rigidity

Execution Procedure: Drive a fully loaded tandem or tri-axle dump truck (minimum 10-ton axle weight) at walking speed over the completed base.

Pass: Surface deflection is under 3/8 inch (10mm) with zero visible wheel rutting. Fail: Tire sinks into rut or adjacent gravel waves/heaves upward.

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Heel-Strike Impact Test

Field Test

Target: Fast spot-check for localized loose compaction pockets

Execution Procedure: Drive the heel of a heavy work boot forcefully down into the compacted surface with full body weight.

Pass: Boot heel produces a sharp, ringing thud with zero visible indentation (< 1/8 inch). Fail: Heel punches into stone or dislodges loose gravel scatter.

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Steel Rebar Penetration Test

Field Test

Target: Check full-depth compaction down to the subgrade layer

Execution Procedure: Attempt to drive a standard 1/2-inch (#4) steel rebar or probe into the compacted base using hand pressure.

Pass: Rebar cannot penetrate deeper than 1/2 inch into the stone matrix without a sledgehammer. Fail: Rebar easily slides into base deeper than 2 inches.

Troubleshooting Protocols

Common Road Base Failure Modes & Remediation

Field Repair Checklist

Soft, Spongy Pumping Under Compactor

Critical Severity

Root Cause:

Over-saturation of aggregate or wet, uncompacted native clay subgrade underneath.

Contractor Solution & Fix:

Stop rolling immediately. Allow surface to dry in the sun for 24–48 hours. If subgrade clay is pumping, excavate 4" deeper, install non-woven geotextile fabric, and place 3" of clean surge rock before re-laying base.

Surface Washboarding, Ravelling & Loose Dust

Moderate Severity

Root Cause:

Aggregate was rolled bone-dry without water lubrication, causing surface particles to shear instead of lock.

Contractor Solution & Fix:

Heavily mist surface with garden hose or water truck spray bar to 6%–7% OMC. Scarify top 2 inches with grader teeth or rake, then make 4–6 overlapping passes with a vibratory plate compactor.

Deep Wheel Rutting in Tire Tracks

High Severity

Root Cause:

Lift thickness was spread too deep (> 4.5" loose), resulting in dense top crust over loose bottom aggregate.

Contractor Solution & Fix:

Excavate rutted section. Re-place material in thin loose lifts not exceeding 3.5 to 4.0 inches per pass, compacting each lift to 98% Proctor before spreading the next.

Edge Blowout & Shoulder Erosion

Moderate Severity

Root Cause:

Lack of lateral confinement or insufficient excavation width along outer driveway margins.

Contractor Solution & Fix:

Always excavate base trench 6 to 12 inches wider than the finished road width. Install compacted soil/crushed stone shoulder berms at a 3:1 slope, or install rigid commercial timber/concrete edge restraints.

Field Construction Standard

Step-by-Step TxDOT Flexible Base Placement & Compaction Sequence

Texas standard construction sequence: subgrade scarification, belly dump windrow spreading, water truck soaking, heavy pneumatic rolling, and chip sealing.

Stage 1 · Day 1 (Morning)

Subgrade Scarification & Lime Treatment

QA Checkpoint

In Central and North Texas (Blackland Prairie), native clays possess high Plasticity Indices (PI 35–60). Scarify top 6 inches, mix with 4% hydrated lime or moisture-condition to +2% over optimum, and compact to 95% Tex-114-E.

Pro Contractor Tips:

Lime stabilization permanently reduces swell potential in Texas clay.

Proof-roll with loaded dump truck before stone placement.

Pass/Fail Verification Standard Zero clay pumping under 20-ton axle load.

Stage 2 · Day 1 (Midday)

Geotextile Separation Fabric Installation

QA Checkpoint

Roll out non-woven geotextile fabric. Overlap seams by 24 inches and pin with steel staples.

Pro Contractor Tips:

Geotextile stops crushed limestone from sinking into wet clay subgrade.

Extend fabric 12 inches beyond future curb lines.

Pass/Fail Verification Standard Fabric pinned flat with zero gaps.

Stage 3 · Day 1 (Afternoon)

First Lift Belly Dump Spreading & OMC Misting

QA Checkpoint

Discharge flexible base in windrows. Spread in a 4.5-inch loose lift. Apply water spray to achieve 6.5% OMC (Tex-113-E).

Pro Contractor Tips:

Belly dump windrowing prevents aggregate segregation.

Hand squeeze test: forms solid clump without dripping water.

Pass/Fail Verification Standard Moisture content verified at 6.0%–7.5% OMC.

Stage 4 · Day 1 (Late Afternoon)

Vibratory & Pneumatic Roller Compaction

QA Checkpoint

Roll with a 5-ton vibratory steel drum followed by a 15-ton pneumatic roller. Make 6 to 8 passes.

Pro Contractor Tips:

Pneumatic rubber tires knead limestone dust into voids, creating an impermeable surface.

Keep tires clean with water spray.

Pass/Fail Verification Standard 100% Tex-113-E density verified.

Stage 5 · Day 2

Final Crown Grading & Two-Course Chip Seal

QA Checkpoint

Cut final 2.5% transverse crown with motor grader. Finish roll and seal with TxDOT two-course surface treatment (AC-15P asphalt + Grade 4 aggregate).

Pro Contractor Tips:

A 2.5% crown sheds intense Texas thunderstorm downpours immediately.

Seal road shoulders with compacted topsoil.

Pass/Fail Verification Standard Crown verified: 2.5% slope confirmed from centerline to shoulders.

Geotechnical Engineering Guide

Texas Transportation Institute (TTI) Engineering Reference: TxDOT Item 247 Base

Technical manual on TxDOT Item 247 grade distinctions, Triaxial compressive strength physics, and managing expansive Texas Blackland clay.

TxDOT Standards Civil Standard Section 01

TxDOT Item 247 Grades 1, 2, and 3: Triaxial Compressive Strength

TxDOT Item 247 establishes strict grading and structural criteria for flexible base materials. Grade 1 requires 100% crushed rock with a minimum Triaxial Compressive Strength of 45 psi at 0 psi lateral pressure (Class 1.0 under Tex-117-E), ensuring extraordinary load-bearing capacity for interstate highways. Grade 2 permits slightly higher plasticity (PI < 10, LL < 35) and requires Triaxial Class 1.5 to 2.3 (35 psi at 0 lateral), making it the standard for city arterials and residential driveways. Grade 3 is a commercial classification with relaxed strength limits suitable for low-volume rural roads and equipment pads.

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