Short answer: in schedule-analysis terms, concurrent delay generally refers to two or more independent delays that affect the critical path during the same period. AACE International Recommended Practice No. 29R-03, Forensic Schedule Analysis (Rev. April 25, 2011, the current revision as of November 2026) sets out technical criteria for identifying it and distinguishes it from pacing. How concurrency is treated in a dispute depends on the governing law and the contract terms, which are matters for counsel and the trier of fact.
How RP 29R-03 describes concurrent delay
RP 29R-03 acknowledges that the industry uses several different definitions of concurrent delay and calls it one of the most contentious areas of forensic schedule analysis. It also notes that a contract's own definition, where one exists, is a major factor, and that its general guidance applies to the extent it does not conflict with the contract.
In summary, the RP describes threshold conditions for treating delays as candidates for concurrency:
- Independence. There are two or more delays that are unrelated and would each have delayed the project even if the other had not occurred. If one delay was caused by the other, they are treated as one delay, not two.
- Different responsibility. The delays are contractually the responsibility of different parties, or one of them is a force majeure type event.
- Involuntary. A delay that was a voluntary choice is generally characterized as pacing rather than concurrent delay.
- Substantial. The delayed work is substantial and not easily curable.
The RP then describes two functional conditions: the delays occur during, or affect, the same analysis period, and each delay, absent the other, would independently have delayed the critical path. The RP also states that counting delays simply because they happened at the same time, without regard to critical path principles, is typically not a sufficient basis for concluding that a delay is not compensable.
Literal and functional concurrency
RP 29R-03 describes two approaches to the timing question:
- Literal concurrency requires the delays to occur at the same time.
- Functional concurrency requires the delays to occur within the same analysis period, often the interval between schedule updates, even if not on the same days.
The RP notes that the functional approach tends to identify more concurrency than the literal approach. It lists other analyst choices that affect findings, including how criticality is defined, whether concurrency is measured by cause or effect, how analysis periods are set, and whether the analysis uses hindsight or only information known at the time. Because these choices affect the findings, an analysis would typically state them.
Pacing delay
RP 29R-03 describes pacing as a conscious, contemporaneous decision by one party to slow its work in response to a delay caused by another party, called the parent delay. Pacing differs from concurrent delay because it is a reaction to the parent delay rather than an independent event. The RP describes criteria commonly used to evaluate whether a delay is pacing, including that a parent delay existed and came first, that the pacing party could have resumed its normal pace, and that there is evidence of the decision to pace at the time. It also notes that contract terms, such as float ownership provisions, can affect whether pacing applies.
Positions parties commonly take
Concurrency is often argued from different directions. Positions commonly seen in disputes include:
- An owner may contend that contractor delays were concurrent on the critical path with owner delays, so the time should be excused but not compensated.
- A contractor may contend that owner delays controlled the critical path and that its own slower work during that period was pacing in response.
- Either party may contend that an alleged delay was not on the critical path, or that two events were really one delay with a single cause.
- Parties may disagree about whether the literal or functional approach applies, or how analysis periods should be drawn.
These are descriptions of positions parties take. Which, if any, is supported in a particular matter depends on the records, the contract and the applicable law.
Law and contract govern the treatment
A schedule analysis can identify which delays affected the critical path and when. Whether a period of concurrent delay is excusable, compensable or apportioned, and how, is determined by the governing law and the contract terms. Those are questions for counsel and, ultimately, the court, arbitrator or other trier of fact. RP 29R-03 itself states that it focuses on technical rather than legal aspects of schedule analysis.
Records a schedule analysis typically reviews
To identify concurrent delays, a schedule analysis commonly draws on:
- The baseline schedule and each schedule update, preferably in native format
- Schedule narratives, submission correspondence and review comments
- Daily reports, superintendent logs and inspection records
- Photographs and site observation records
- RFIs, submittals, directives, change orders and their dates
- Meeting minutes and correspondence describing events and responses
- Delivery, procurement and staffing records, including crew size changes
- Notices and time extension requests, with responses
These records help establish when each event started and ended, which work it affected, whether one event was a response to another, and whether a slowdown was a decision made at the time.
Related reading
For an overview of the methods used to measure delay, see How schedule delay analysis methods work, and what each needs. Oxley's construction delay expert witness work is led by Daniel R. Zorrilla, J.D., BSBC, CGC, CFCC.
This article is general information, not legal advice. An opinion in any matter depends on that matter's records and assignment. How a contract or the law applies depends on the facts; consult counsel.