When construction delays to the anticipated pace and progress of a project occur, it can become necessary to counteract the negative impacts to the schedule and “recover” time lost. Likewise, a schedule may need to be shortened to achieve completion at an earlier date. In both scenarios, acceleration – an initiative to increase efforts to complete performance at a faster pace than originally anticipated, despite excusable delay – may be applied.
In this article, we will look at:
- Acceleration scenarios
- Cost recovery options
- Application methods
- Key factors in using acceleration methods successfully
Three Acceleration Scenarios
Acceleration may happen on a construction project under three basic scenarios:
1. Voluntary Acceleration
This occurs when the contractor makes up for time lost due to non-excusable critical path delays for which they are responsible. Consequently, voluntary acceleration is rarely the subject of construction claims or disputes as almost all contracts include a “time is of the essence” clause. Thus, the increased cost and risk of acceleration are generally used to offset the risk of a larger financial impact – and the costs are absorbed by the contractor.
2. Directed Acceleration
Directed acceleration occurs when it can be demonstrated in the project record that the contractor is ordered – typically by the owner – to accelerate a scope of work. Ideally, there is an understanding that, with direction, compensation will be made for these efforts in the form of a change order. However, the responsibility for the acceleration may come into dispute when pursuing the costs from the directing party. For example, the owner may believe that the contractor experienced production delays and should accelerate, while the contractor may believe that the delays were, in fact, owner-caused by issues such as site access, delayed review of submittals, or changes to the design, so it could not execute its work in the time planned. Such disputes will be resolved through an acceleration claim.
3. Constructive Acceleration
This type of acceleration is more complex and heavily dependent on the situation. More commonly, constructive acceleration is seen in cases where the contractor incurs excusable delays and submits a request for an extension, but the owner rejects the request and continues to hold the contractor to contractual deadlines. Thus, the contractor’s only option is to accelerate work to meet the schedule. To distinguish constructive acceleration from voluntary acceleration, the contractor must demonstrate and prove five conditions established by the General Services Board of Contract Appeals: 
- the contractor has experienced a period of excusable delay under the contract;
- the contractor requested an extension of the contract schedule in a timely and sufficient manner;
- the owner denied the contractor’s request or did not respond within a reasonable time;
- the owner’s demand for completion within the original performance period (or earlier than the entitled period of excusable delay); and
- the contractor incurred additional costs for acceleration efforts.
Note that delays need not be compensable, only excusable, to serve as the basis of the contractor’s constructive acceleration claim to recover additional costs.
Risks of Schedule Recovery and Acceleration Methods
A contractor can accelerate a schedule using one of two general methods:
- Activity crashing: shortening the duration of a task by adding more resources or costs.
- Activity overlapping: performing activities in parallel instead of in sequence, as planned.
While crashing the activities naturally increases the direct cost due to the cost of extra resources, higher overtime rates, and any other methods needed to reduce task duration, there are other less direct costs to be considered.
Additional crews on a regular shift, overtime rates, and multiple shifts may result in higher costs since they tend to reduce productivity. Studies on the effects of overtime on construction labor productivity have consistently demonstrated an inverse relationship between the amount of overtime work and labor productivity, as shown below.
Furthermore, the longer that overtime schedules are relied upon to recover from delays, the more likely it is that further reductions in worker productivity will be observed. As overtime continues, crew exhaustion may further reduce overall productivity rates by as much as 30-40% within 10 weeks. 
According to a National Research Council of Canada Institute for Research in Construction guidebook on productivity, overstaffing and crowding of work areas both negatively affect productivity as shown below. 
- dilute supervision
- increase strain on equipment/material demands
Overcrowding of spaces
- prevents workers from having adequate space to work effectively
- reduces morale
- interferes with the movement of materials and equipment
Activity overlapping, on the other hand, does not necessarily add any immediate additional direct costs but often introduces added risk and greater uncertainty to the project plan. For example, starting a successor activity while the predecessor is still in progress increases the likelihood of an impact to the successor activity should a change or rework be required on the predecessor activity. Any changes in the predecessor activity will likely produce rework for the successor task and may prolong the duration of the successor task beyond what would have been necessary had the same rework had been performed as originally scheduled. For example, if a mistake or change was made in the progress of roughing in walls but affected areas have already been enclosed due to activity overlapping, the impact of rework will now include the removal and reinstallation of drywall as well as the correction of the rough-in work. Therefore, overlapping may not ultimately be as efficient as expected because of uncertainties that create additional work and delays.
Furthermore, the overlapping of activities can have the same productivity impacts observed with increasing crew sizes for individual activities. Having activities occur in parallel may result in crowding and congestion in project areas with limited space or access and in turn, decrease productivity. Due to the complexity and uniqueness of each activity on each project, overlapping should be considered deliberately, with a greater focus on preemptive coordination to detect possible issues before they manifest as additional delays.
Regardless of the method, it is important for contractors to understand the implications of acceleration so the potential cost is fully understood and the anticipated productivity is realistic.
Successful Acceleration Claims
Detailed Records are the Key
There are several aspects of construction disputes involving acceleration that need to be understood when faced with a potential delay scenario or when pursuing such a claim. Most importantly, acceleration claims can be particularly difficult to pursue. Segregating self-inflicted damages from those solely attributable to the required acceleration efforts requires detailed cost and schedule data as well as sufficient notice documentation among other things. The difficulty demonstrating entitlement and proving damages directly associated with implied acceleration orders reiterates the importance of proper record keeping for schedule updates, communication with the owner, and cost tracking. The level of detail of these records greatly influences the chances of recovery as well as decreases the cost associated with pursuit.
Improving the understanding of acceleration claims, methods of acceleration, as well as their risks, can help contractors and owners efficiently identify and resolve acceleration-related construction delay claims.