Planning motorway roadworks: closures, crews and the order of the sections
In which order, in which closures and with how many crews are the 16 work zones of a 12 km motorway stretch renewed, so that the stretch is finished as early as possible at a sensible cost?
Drag to rotate, scroll or pinch to zoom. The schedule below plays the whole renewal, night by night. The buttons switch between the plan with 3 crews, one crew section by section and a plan with 4 crews. Hover a bar or a section for details. Plan computed with a Timefold model.
The planning question
A fictional six-lane motorway stretch of 12 km is renewed. It has 8 sections of 1.5 km, each with two carriageways, which gives 16 work zones. A carriageway is the side of the motorway for one direction, here with 3 lanes and a hard shoulder. Five sections get a new binder course and surface course, the two asphalt layers on top of the road base. Three sections only get a new surface course. The work starts on Monday 19 April.
A crew mills off the old asphalt with a milling machine and then lays the new layers with a paver train: the paver, the trucks that feed it and two rollers. The crews share 2 milling machines and 2 paver trains. A carriageway can close at night from 20:00 to 05:00 (Monday to Thursday) or for a whole weekend from Friday 20:00 to Monday 05:00. While it is closed, its traffic crosses over to the other carriageway, so in one section only one side can close. A marking team then applies the final markings by day, with only the right lane closed.
Working hours, rates and the calendar are assumptions for this example. A full renewal takes 34 crew hours per zone, a new surface course 13 hours. A night shift costs 6,500 €, a crew is booked at 8,000 € per week, a night closure costs 2,000 € and a weekend full closure 22,000 € for the diversion. The site costs 4,500 € per day for traffic guidance and safety. The 3D view shortens the stretch: 1 km is drawn as 100 m, widths and vehicles are true to size.
How we plan it
The Timefold model decides two things per work zone: its place in the order of the works and whether its asphalt is laid in night closures or in one weekend full closure. For every change it builds the whole plan, closure window by closure window. A crew with a zone in progress continues when the zone may close and a machine is free. A free crew takes the next zone in the order that may close in this window. A crew rests 11 hours between two shifts. From the plan follow the finish date, the nights with a closure and the cost of crew shifts, booked crews, closures, markings and site days, which the model keeps low.
The number of crews is compared: the model plans the stretch with 1, 2, 3, 4 and 5 crews, and the page shows the crew count with the lowest cost. The comparison is one crew that renews the stretch section by section in night closures, computed with the same code.
What the plan shows
| KPI | Optimized plan | Comparison: 1 crew, section by section |
|---|---|---|
| finished after (weeks) | 5.2 −11.3 | 16.5 |
| cost (thousand €) | 907 −334 | 1,241 |
| nights with a closure | 26 −36 | 62 |
Decisions
- order of the 16 work zones (8 sections, 2 carriageways)
- night closures or one weekend full closure per zone
- number of asphalt crews (1 to 5 compared)
Constraints
- closures only at night (Monday to Thursday, 20:00 to 05:00) or as a weekend full closure (Friday 20:00 to Monday 05:00), none around public holidays
- per section only one carriageway closed (traffic crosses over to the other one), closures on the same carriageway at least one open section apart
- every crew, both milling machines and both paver trains work on one zone at a time
Objective
early completion, few nights with a closure, low cost of crews, closures and site
Questions
How much staff makes sense?
With 1 crew the stretch takes 11.1 weeks, with 2 crews 6.7 weeks and with 3 crews 5.2 weeks. A fourth crew finishes one day earlier and costs 36,000 € more. A fifth crew finishes no earlier. The limit is the 2 paver trains and the closure rules: in one night only a few zones may close, and only 2 of them can be paved.
Why are some zones renewed in a weekend full closure?
A weekend gives 54 working hours in one piece. A full renewal of a zone fits into one weekend, at night it needs 5 nights. The plan uses 5 weekend closures for zones with a new binder course, where the gain is largest, and lays the other zones at night. Each weekend closure costs 22,000 € for the diversion, and the shorter site time pays for it.
Why does the comparison take 16.5 weeks?
One crew works through the zones in chainage order, 4 nights a week, and there are no closures around Ascension, Whitsun and Corpus Christi. That makes 62 nights with a closure. In the plan three crews work at the same time in zones far enough apart, and the stretch needs 26 nights with a closure (a weekend counts as 3 nights).
Does the model simulate traffic jams?
No. It keeps one carriageway open in every section and counts the nights with a closure. Traffic volumes per hour or a cost for the delay of road users can be added as a further objective.
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