So…You read the title.  How much is a clean inspection worth? What do you think?  Some motor carriers have driver incentive programs: Get $50 for each clean inspection, for example.  That is certainly one way to measure it.  I am talking about something else though.  Specifically, what is the impact of a clean inspection under CSA?

Vigillo has been helping transportation professionals better understand CSA since the first methodology was published in 2010.  I’ll tell you some of the misconceptions I’ve heard.  More importantly, let’s really unravel it.  Let’s dig deep and lay out exactly what the effect (or non-effect in some cases) that a zero-defect inspection has on a motor carrier’s CSA score.  The answers may surprise you.

Misconceptions about Clean Inspections

First, clean inspections are a somewhat complicated area within CSA so it does not surprise me that there are many different answers to this question.  Here is just a brief list of differing explanations I have heard:

  • Clean inspections don’t count at all
  • Clean inspections wipe away violations a bit at a time
  • Three clean inspections cancel out one violation
  • Clean inspections dilute violations
  • Clean inspections only count for some BASICs
  • Clean inspections don’t exist

These can’t all be true, right?  So misconceptions about clean inspections abound.  Let’s start at the beginning and work our way through.

What Exactly is a Clean Inspection?

Let’s keep things nice and simple.  In regular conversation, a clean inspection is simply an inspection that has no violations.  Other names for clean inspections include “zero-defect inspections” and “no violation inspections.”  Same thing.

How Common are Clean Inspections?

In a word – very.  The FMCSA Analysis & Information Online website reports that for calendar year 2011, there were a total of 3,588,020 inspections conducted.  Of these, 1,351,609 of these had no violations.  That’s 38% of all inspections.

Two BASIC Examples

Here’s the thing – in terms of CSA points, you need to look at inspection points one BASIC at a time.  The FMCSA evaluates each of the 7 BASICs separately and differently.  There are different scoring rules, different calculations, etc.  So let’s start by taking a look at two BASICs and see how they handle clean inspections (hint: very differently).  Below, I’ll discuss the impact of clean inspections in Unsafe Driving and Driver Fitness.

Unsafe Driving BASIC

The key calculation in the Unsafe Driving BASIC determines a carrier’s BASIC measure.  For Unsafe Driving, the calculation is below:

In very simplified language, this is your CSA Points divided by your number of power units.  Any reference to number or type of inspections here?   None whatsoever.  By the way, “utilization factor” is only concerned with vehicle miles traveled and number of power units – so no connection to inspections there either.

Example: Let’s take a simplified example.  Please note that I am not getting into all the complicating factors so that this is easier to understand.  Let’s say a carrier has 150 violation points in this BASIC and has 50 power units (with no utilization factor bonus), that works out to be a BASIC measure of 150 divided by 50 which equals 3.  To determine the percentile score of this carrier, all carriers in this same safety event group are then arranged high to low based on their BASIC measure and given a percentile.  Got it?

Questions:Would anything be different if this carrier had zero clean inspections?  How about 10?  How about 100? The answer to all of these questions is that the BASIC measure would be unchanged and therefore the CSA percentile score in the Unsafe Driving BASIC is unchanged as well.

Conclusion: NO EFFECT. For purposes of the Unsafe Driving BASIC, Clean Inspections have absolutely no effect on a carrier’s CSA scores, such as BASIC measure or percentile.  Furthermore, inspections that have violations – but no unsafe driving violations – have the same effect on the Unsafe Driving BASIC: that is, no effect at all.  Hard to believe?  You would not be the first to think so.

Fatigued Driving (HOS) BASIC

A motor carrier’s Fatigued Driving (HOS) BASIC score is determined primarily from this calculation:

In other words, take the total violations points (from fatigued driving / hours of service violations) and divide them by time-weighted relevant inspections.  The key question then is: What the heck is a relevant inspection?

Relevant Inspection Defined. A relevant inspection in the Fatigued Driving BASIC is, according to the SMS Methodology version 2.2:

A Relevant Inspection is any Driver Inspection (Level 1, 2, 3, or 6), including those that do not result in a violation in the BASIC, or any other inspection resulting in an applicable BASIC violation

So what does that mean – especially in terms of a clean inspection?  Well, it means that an inspection will count as long as it is either one of the following: (a) a driver inspection, meaning a level 1, 2, 3, or 6 inspection OR (b) the inspection included a fatigued driving violation.   Since part (b) is by definition not a clean inspection we can forget about that part.  However part (a) appears to include clean inspections as long as they are a level 1, 2, 3, or 6.  So, a clean inspection will count in this BASIC.  Fantastic!  Even better, because the bad violation points on the top of the calculation (in the numerator) are divided or diluted by the inspections (in the denominator), clean relevant inspections clearly will help the carrier’s BASIC measure which improves the BASIC percentile.

How Much does a Clean Inspection Matter? Wait a second…It’s great that a clean inspection is included and can help the carrier’s score.  Now the question is: how much does it count?  Let’s look at a fictional motor carrier:

Let’s say Carrier A has 100 violation points in this BASIC.  Next we divide that by time-weighted relevant inspections.  Let’s say that number is 25.  100 divided by 25 equals 4 which would be the BASIC measure.

Let’s say Carrier A has added one more clean inspection that was a level 1 inspection.  It definitely helps the carrier but by how much?  the first question we have is what is the time weighting? Here’s how the time weighting works:

  • Recent inspections from 0 – 6 months are triple weighted
  • Inspections from 7-12 months are double weighted
  • Older Inspections from 13-24 are single weighted
  • Inspections older than 24 months are not included

The best case is that a new clean inspection is recent (within the last 6 months) so it therefore counts as 3 time-weighted inspection points.  Using our example from above, this carrier would 100 violation points divided by 28 (25 +3) time-weighted inspection points, so the BASIC measure comes out to be 3.57 – better (lower) than the 4 it was previously!  That is an improvement of 11% in the BASIC measure.  Not bad, right?

The harder question is what is the percentile improvement due to this clean inspection?  Unfortunately that is tougher to answer because the change is different in each safety event group.  Remember the percentile is applied after all motor carriers are, in a sense, lined up against a wall and given a ranking best to worst.  The percentile change will depend upon how many motor carriers you passed with this change.

Conclusion: Clean inspections DO have a positive effect on a carrier’s Fatigued Driving BASIC scores. How big an effect depends upon the recency of the clean inspection and the BASIC measures of the other carriers in the safety event group.

Two Categories of BASICs

So far we’ve seen one BASIC where clean inspections have no effect (Unsafe Driving) and one BASIC where clean inspections help the carrier’s CSA score (Fatigued Driving).  It turns out that all remaining BASICs can be divided into these two categories – for exactly the reasons we saw in our two example BASICs above.

BASICs where Clean Inspections DO NOT CHANGE CSA Scores

Clean inspections have no effect on a carrier’s score in the following BASICs simply because the official calculation does not take into account any clean inspections:

  • Unsafe Driving

  • Crash

BASICs where Clean Inspections IMPROVE CSA Scores

For the BASICs listed below, clean inspections positively help a carrier’s score because the calculation used dilutes violation points by relevant inspections – including relevant clean inspections:

  • Fatigued Driving (HOS)

  • Driver Fitness

  • Controlled Substances / Alcohol

  • Vehicle Maintenance

  • Cargo-Related

  • HazMat (future)

Note that the FMCSA has announced that the Cargo-Related BASIC will be replaced by the HazMat BASIC in the last half of 2012.  The SMS Methodology March 2012 version 3.0 Motor Carrier Preview shows that the HazMat BASIC is positively affected by clean inspections as well.

Wrapping Up:

I am hopeful this article can clear up some of the misconceptions about clean inspections and CSA.  A few parting thoughts:

  • Understand Clean Inspections: As a transportation safety professional, it makes sense to understand how this key federal safety initiative of CSA works.  Inspections, both clean and not-so-clean, are an important part of it.  Plus – you’ll look smarter, be more confident, and generally impress folks when you know what you are talking about!


  • Unsafe / Crash: If your carrier is working to reduce Unsafe Driving or Crash BASIC scores, focusing on clean inspections may not be the most productive way to go about it since these BASICs do not consider clean inspections in their calculations.


  • Value of Clean Inspections: One transportation safety professional I discussed this topic with put it something like this: Generally speaking, think about violations as costing you dollars while clean inspections give you back pennies.


  • DataQs: Consider submitting DataQ challenges to get clean inspections counted if they did not get reported to the FMCSA.  There is very little downside to this effort – especially if you have the documentation.


  • Changes ahead! In the exciting world of CSA, there are always changes – changes to the methodology, to enforcement, to reporting.  Vigillo works hard to keep our customers in the know for all of these changes.

I welcome your questions and comments.  Thanks for reading!