Delay Analysis
Overview
Analyze construction schedule delays for project recovery and claims. Perform time impact analysis (TIA), identify concurrent delays, calculate delay damages, and prepare documentation for dispute resolution.
"Proper delay analysis is essential for fair resolution of construction disputes" — DDC Community
Delay Analysis Methods
┌─────────────────────────────────────────────────────────────────┐
│ DELAY ANALYSIS METHODS │
├─────────────────────────────────────────────────────────────────┤
│ │
│ As-Planned vs As-Built │ Time Impact Analysis (TIA) │
│ ───────────────────── │ ──────────────────────────── │
│ Compare original to │ Insert delay events into │
│ actual schedule │ schedule to measure impact │
│ │ │
│ Windows Analysis │ Collapsed As-Built │
│ ──────────────── │ ───────────────── │
│ Divide project into │ Remove delays from as-built │
│ time periods │ to find "but-for" completion │
│ │
└─────────────────────────────────────────────────────────────────┘Technical Implementation
from dataclasses import dataclass, field
from typing import List, Dict, Optional, Tuple
from datetime import datetime, timedelta
from enum import Enum
from collections import defaultdict
class DelayType(Enum):
EXCUSABLE_COMPENSABLE = "excusable_compensable" # Owner caused - time + money
EXCUSABLE_NON_COMPENSABLE = "excusable_non_compensable" # Neither party - time only
NON_EXCUSABLE = "non_excusable" # Contractor caused - no relief
CONCURRENT = "concurrent" # Both parties - complex
class DelayCause(Enum):
OWNER_CHANGE = "owner_change"
LATE_INFORMATION = "late_information"
DIFFERING_CONDITIONS = "differing_conditions"
PERMIT_DELAY = "permit_delay"
WEATHER = "weather"
LABOR_SHORTAGE = "labor_shortage"
MATERIAL_DELAY = "material_delay"
SUBCONTRACTOR = "subcontractor"
COORDINATION = "coordination"
ACCESS = "access"
FORCE_MAJEURE = "force_majeure"
@dataclass
class DelayEvent:
id: str
description: str
cause: DelayCause
delay_type: DelayType
start_date: datetime
end_date: datetime
affected_activities: List[str]
responsible_party: str
documented: bool = True
supporting_docs: List[str] = field(default_factory=list)
calculated_impact: int = 0 # days
concurrent_with: List[str] = field(default_factory=list)
@dataclass
class ScheduleVersion:
version_id: str
version_type: str # baseline, update, as-built
data_date: datetime
completion_date: datetime
activities: Dict[str, Dict] # activity_id -> {start, finish, duration}
@dataclass
class WindowPeriod:
window_id: str
start_date: datetime
end_date: datetime
planned_progress: float
actual_progress: float
delay_days: int
delay_events: List[str]
responsible_parties: Dict[str, int] # party -> delay days
@dataclass
class DelayAnalysisReport:
project_name: str
analysis_date: datetime
original_completion: datetime
actual_completion: datetime
total_delay: int
excusable_delay: int
non_excusable_delay: int
concurrent_delay: int
delay_events: List[DelayEvent]
delay_by_cause: Dict[str, int]
delay_by_party: Dict[str, int]
recommended_extension: int
potential_damages: float
class DelayAnalyzer:
"""Analyze construction schedule delays."""
# Daily delay costs by project size
DEFAULT_DAILY_COSTS = {
"small": 5000, # < $10M
"medium": 15000, # $10M - $50M
"large": 40000, # $50M - $200M
"mega": 100000 # > $200M
}
def __init__(self, project_name: str, contract_completion: datetime):
self.project_name = project_name
self.contract_completion = contract_completion
self.delay_events: Dict[str, DelayEvent] = {}
self.schedule_versions: Dict[str, ScheduleVersion] = {}
self.window_periods: List[WindowPeriod] = []
self.daily_cost = self.DEFAULT_DAILY_COSTS["medium"]
def set_daily_delay_cost(self, cost: float):
"""Set daily delay cost for damages calculation."""
self.daily_cost = cost
def add_schedule_version(self, version_id: str, version_type: str,
data_date: datetime, completion_date: datetime,
activities: Dict[str, Dict]) -> ScheduleVersion:
"""Add schedule version for analysis."""
version = ScheduleVersion(
version_id=version_id,
version_type=version_type,
data_date=data_date,
completion_date=completion_date,
activities=activities
)
self.schedule_versions[version_id] = version
return version
def add_delay_event(self, id: str, description: str,
cause: DelayCause, delay_type: DelayType,
start_date: datetime, end_date: datetime,
affected_activities: List[str],
responsible_party: str,
supporting_docs: List[str] = None) -> DelayEvent:
"""Add delay event for analysis."""
event = DelayEvent(
id=id,
description=description,
cause=cause,
delay_type=delay_type,
start_date=start_date,
end_date=end_date,
affected_activities=affected_activities,
responsible_party=responsible_party,
supporting_docs=supporting_docs or []
)
self.delay_events[id] = event
return event
def perform_as_planned_vs_as_built(self) -> Dict:
"""Perform As-Planned vs As-Built analysis."""
baseline = self.schedule_versions.get("baseline")
as_built = self.schedule_versions.get("as_built")
if not baseline or not as_built:
raise ValueError("Need baseline and as-built schedules")
total_delay = (as_built.completion_date - baseline.completion_date).days
# Analyze each activity
activity_delays = []
for act_id, baseline_act in baseline.activities.items():
if act_id in as_built.activities:
as_built_act = as_built.activities[act_id]
baseline_finish = baseline_act['finish']
actual_finish = as_built_act['finish']
if isinstance(baseline_finish, str):
baseline_finish = datetime.fromisoformat(baseline_finish)
if isinstance(actual_finish, str):
actual_finish = datetime.fromisoformat(actual_finish)
delay = (actual_finish - baseline_finish).days
if delay > 0:
activity_delays.append({
'activity_id': act_id,
'planned_finish': baseline_finish,
'actual_finish': actual_finish,
'delay_days': delay
})
return {
'method': 'As-Planned vs As-Built',
'baseline_completion': baseline.completion_date,
'actual_completion': as_built.completion_date,
'total_delay': total_delay,
'activity_delays': sorted(activity_delays, key=lambda x: -x['delay_days'])
}
def perform_time_impact_analysis(self, delay_event_id: str) -> Dict:
"""Perform Time Impact Analysis for specific delay event."""
if delay_event_id not in self.delay_events:
raise ValueError(f"Delay event {delay_event_id} not found")