How Do You Calculate Transport Index?
Use this calculator to estimate the Transport Index (TI) for radioactive material packages. Enter the maximum radiation level measured at 1 meter from the package, choose the unit, add the maximum surface dose rate, and the tool will calculate TI, suggest a label category, and visualize how your result compares with common regulatory thresholds.
Transport Index Calculator
Ready to calculate
Enter your survey data and click the button. This calculator uses the standard TI relationship: the maximum radiation level at 1 meter in mSv/h multiplied by 100, then rounded up to one decimal place.
Expert Guide: How Do You Calculate Transport Index?
If you work with radioactive material shipments, one of the most practical questions you will face is: how do you calculate transport index? The Transport Index, usually abbreviated TI, is a regulatory number used in package marking, labeling, segregation, and loading decisions. It is not just a paperwork detail. TI directly affects how a package can be handled in commerce, how close it can be placed to workers and the public, and which controls are required during transport.
At its core, the Transport Index is based on radiation dose rate measured at a distance of 1 meter from the external surface of the package. In the most common SI approach, you take the maximum dose rate at 1 meter in millisieverts per hour, multiply by 100, and then round the result up to the next tenth. In U.S. customary units, if the reading is already in millirem per hour at 1 meter, the TI is numerically the same value, again rounded up to one decimal place. This simple relationship is easy to state, but many mistakes happen in the field because people use the wrong measurement point, forget to use the maximum reading, or confuse surface dose rate with the 1 meter dose rate.
The Basic Formula
The standard way to calculate Transport Index is:
- TI = 100 × maximum radiation level at 1 meter in mSv/h
- Then round up to the next tenth
If your meter reads in mrem/h at 1 meter, the value is numerically the TI before rounding. That means:
- 0.7 mrem/h at 1 meter becomes TI 0.7
- 0.71 mrem/h at 1 meter becomes TI 0.8
- 2.31 mrem/h at 1 meter becomes TI 2.4
Important: The TI is based on the highest measured radiation level at 1 meter from the package, not an average and not the surface reading. Surface dose rate still matters for determining the correct package label category, but it is a different measurement with a different role.
Why the Transport Index Matters
TI serves as a practical risk control tool. Shipping regulations use it to help determine how packages should be labeled and how they should be segregated from occupied areas, undeveloped film, and other cargo. It is also used in shipment planning when multiple packages are loaded together. If each package has a TI, the shipment planner can sum those values to understand the radiation control profile of the consignment.
Because TI is tied to the dose rate at 1 meter, it provides a fast indicator of radiation intensity in the working zone around a package. That is why it is useful for drivers, warehouse staff, radiation safety officers, emergency responders, and compliance teams alike.
Step by Step: How to Calculate TI Correctly
- Survey the package properly. Use a calibrated radiation survey meter appropriate for the radionuclide and energy range involved.
- Find the highest reading at 1 meter. Measure around the package and identify the maximum radiation level at exactly 1 meter from the external surface.
- Convert units if needed. If the reading is in mSv/h, multiply by 100. If the reading is in mrem/h, the number is already the TI basis.
- Round up to one decimal place. Do not round to the nearest tenth. Round upward. A raw TI of 0.71 becomes 0.8, not 0.7.
- Record the TI on the package and paperwork where required. Confirm consistency with the package label category and shipping documentation.
Worked Examples
Example 1: A package has a maximum measured dose rate at 1 meter of 0.013 mSv/h. Multiply by 100 and you get 1.3. Because the value is already at one decimal place, the TI is 1.3.
Example 2: A package has a 1 meter reading of 0.004 mSv/h. Multiply by 100 and you get 0.4. TI is 0.4.
Example 3: A package has a 1 meter reading of 2.31 mrem/h. The TI basis is 2.31. Rounded up to one decimal place, the TI becomes 2.4.
Example 4: A package has a 1 meter reading of 0.005 mSv/h and a surface reading of 0.004 mSv/h. TI would be 0.5. However, because White-I packages require TI of 0 and very low surface dose rate, this package would not be White-I even though the numbers are small.
Transport Index Versus Label Category
People often ask whether TI alone determines the package label. The answer is no. TI is a major factor, but the label category also depends on the maximum radiation level on the external surface of the package. In practice, the package must satisfy both the TI range and the surface dose rate limit for the category.
| Label Category | Maximum Surface Dose Rate | Transport Index Range | Typical Interpretation |
|---|---|---|---|
| Radioactive White-I | Not more than 0.005 mSv/h | TI = 0 | Very low external radiation level. Minimal transport control burden compared with higher categories. |
| Radioactive Yellow-II | More than 0.005 mSv/h but not more than 0.5 mSv/h | More than 0 but not more than 1 | Moderate control category for packages with low but measurable radiation at 1 meter. |
| Radioactive Yellow-III | More than 0.5 mSv/h but not more than 2 mSv/h under typical non-exclusive use limits | More than 1 but not more than 10 under typical non-exclusive use limits | Higher control category commonly requiring tighter segregation and handling attention. |
These are widely recognized regulatory limits used in international and U.S. transport frameworks. Always confirm the latest modal and jurisdiction-specific rules before shipment, especially when exclusive use, LSA, SCO, fissile controls, or international carriage conditions apply.
Real Regulatory Numbers and Conversion Benchmarks
One reason TI calculations go wrong is unit confusion. Here are the key conversion facts that matter in practice:
| Measurement | Equivalent Value | TI Impact | Why It Matters |
|---|---|---|---|
| 0.01 mSv/h at 1 meter | 1.0 mrem/h at 1 meter | TI 1.0 | This is the exact crossover where the SI formula and mrem/h numeric shortcut align. |
| 0.005 mSv/h surface dose rate | 0.5 mrem/h surface dose rate | Supports White-I only if TI is also 0 | This threshold is a common compliance checkpoint for low-radiation packages. |
| 0.5 mSv/h surface dose rate | 50 mrem/h surface dose rate | Upper surface benchmark for Yellow-II | Above this level, a package cannot remain in the Yellow-II category. |
| 2 mSv/h surface dose rate | 200 mrem/h surface dose rate | Common non-exclusive use upper surface benchmark for Yellow-III | Values above this usually trigger a review for special controls or non-compliance. |
Common Mistakes When Calculating TI
- Using the surface reading instead of the 1 meter reading. TI does not come from contact dose rate.
- Using an average instead of the maximum measured point. Regulations are concerned with the highest radiation level around the package.
- Rounding incorrectly. TI is rounded up, not rounded to the nearest tenth.
- Skipping unit conversion. A meter set to mrem/h changes how the number should be interpreted compared with mSv/h.
- Assuming TI alone determines the label category. Surface dose rate is also required.
- Ignoring shipment configuration. Multiple packages in one vehicle may require aggregate TI review and segregation planning.
How Shipment Planners Use Aggregate TI
Although each package has its own TI, shipments often contain multiple packages. In that situation, logistics personnel frequently total the TI values across all packages to estimate loading intensity and segregation needs. This is especially useful for planning trailer layouts, container positions, and access restrictions in warehouses and transfer stations. The calculator above includes a package count so you can estimate an aggregate TI quickly. Keep in mind that aggregate TI is a planning aid and does not replace the need to comply with exact package-specific and modal rules.
Best Practices for Accurate Measurement
- Use a current, calibrated instrument with documented response characteristics.
- Confirm the distance from the package surface carefully. Small positioning errors can affect low-level readings.
- Survey all sides and corners because hot spots may not be obvious.
- Record both the 1 meter maximum and the surface maximum in the same survey log.
- Check whether any shielding changes, overpacks, or package orientation could affect readings.
- Have a second qualified reviewer verify borderline values, especially near category cutoffs.
What the Authorities Say
For official definitions and detailed transport requirements, consult primary regulatory sources instead of relying only on summaries. Useful references include the U.S. Nuclear Regulatory Commission glossary entry for TI, the U.S. electronic Code of Federal Regulations for radiation level limits in transport, and university radiation safety guidance that explains the operational side of package surveys and labels:
- U.S. Nuclear Regulatory Commission: Transport Index definition
- eCFR Title 49: Radiation level limitations and transport controls
- Princeton University Radiation Safety shipping guidance
How to Interpret Your Calculator Result
When the calculator returns a TI, treat that result as one key compliance indicator. A TI below 1 does not automatically mean the package is simple to ship. You still need to examine the surface dose rate, the package type, radionuclide limits, contamination controls, and the transport mode. Likewise, a TI above 1 does not necessarily mean the shipment is prohibited. It means the shipment likely falls into a higher control category and must be handled under the appropriate requirements.
For example, a package with TI 0.4 and surface dose rate 0.3 mSv/h may fit within Yellow-II, while a package with TI 2.4 and surface dose rate 1.1 mSv/h points toward Yellow-III. If your measurements exceed common non-exclusive use benchmarks, you may need exclusive use controls or a more detailed regulatory review. The right answer always depends on the full shipment context.
Final Takeaway
If you remember only one thing, remember this: to calculate Transport Index, take the highest measured radiation dose rate at 1 meter from the package, convert it to mSv/h if needed, multiply by 100, and round up to one decimal place. Then compare that TI together with the maximum surface dose rate to determine the likely package label category and transport controls. That disciplined approach keeps your calculations defensible, repeatable, and aligned with recognized shipping practice.