labour rate variances
difference between planned labour rates and actual labour rates.

ladder*
device for representing a set of overlapping activities in a network diagram.
Note: The start and finish of each succeeding activity are linked only to the start and finish of the preceding activity by lead and lag activities, which consume only time.

lag*
a) In a network diagram, the minimum necessary lapse of time between the finish of one activity and the finish of an overlapping activity
b) delay incurred between two specified activities.

late dates
calculated in the backward pass of time analysis, late dates are the latest dates by which an activity can be allowed to start or finish.

latest event time*
Latest time by which an event has to occur within the logical and imposed constraints of the network, without affecting the total project duration.

late event date
calculated from backward pass, it is the latest date an event can occur.

latest finish time*
the latest possible time by which an activity has to finish within the logical activity and imposed constraints of the network, without affecting the total project duration.

latest start time*
latest possible time by which an activity has to start within the logical and imposed constraints of the network, without affecting the total project duration.

lead*
in a network diagram, the minimum necessary lapse of time between the start of one activity and the start of an overlapping activity.

lead contractor
the contractor who has responsibility for overall project management and quality assurance.

leadership
getting others to follow.

letter of intent
a letter indicating an intent to sign a contract, usually so that work can commence prior to signing that contract.

levelling
See resource levelling.

life cycle
a sequence of defined stages over the full duration of a project.

life cycle costing
when evaluating alternatives, life cycle costing is the concept of including acquisition, operating and disposal costs.

likelihood
Assessment of the probability that a risk will occur.

line manager
the manager of any group that makes a product or performs a service.

linked bar chart
a bar chart that shows the dependency links between activities.

logic
see network logic.

logic diagram
a diagram that displays the logical relationships between project activities

logical relationship
a logical relationship is based on the dependency between two project activities or between a project activity and a milestone.

loop*
an error in a network which results in a later activity imposing a logical restraint on an earlier activity.