What is the justification for working on such large stretches of road?

Question

I live and work in the UK, a country known for relentless roadworks.

Last week I drove through roadworks on the M1 that lasted for 18 miles, necessitating road users driving at 50 mph. Of course, almost all of this impressive stretch was simply coned off, with active work only present on one or two small sites. Signs indicate that work will continue into next year.

What justification is there for keeping such a large section of road cordoned off for improvements? Is it a safety or economical consideration? It would seem prudent to close off mile sections at a time to increase traffic flow and reduce the number of cones/signs/average speed cameras in use, but perhaps there is an underlying reason I am missing?

Answer 1

I'll give you some considerations that you may not be aware of. Also, take the disclaimer that I'm in the US (but construction is construction, right?)

1. Frequently moving construction cones/barrels along the road is less efficient than setting them out once and only making minor adjustments to their location.

2. Depending on the type of work being done, some sections may require a certain length of time before the next bit of work is done. This is frequently the case with painting the lines. Painting specifications usually require that the concrete or asphalt sit for about a week before painting can begin.

3. Not every crew can do all of the jobs. Sometimes scheduling certain crews to come do their part means that specific tasks may be held back while the workers are on a different job.

4. Keeping a large stretch of road closed allows for flexibility in where equipment and people can be moved after finishing their current job.

5. Shortening the construction zone may not have that great of an effect on the throughput of the road. If you take for granted that there will be a bottleneck somewhere, its exact location doesn't matter much. Also, once you are in a single line, the speed limit may be close to the optimum speed. Studies have shown that the highest volume of vehicles occur around 55 miles per hour.

6. There is some safety benefit to long construction zones. The majority of accidents will occur at the beginning of the zone. Keeping workers away from those areas is safer.

7. Probably the biggest reason when you combine all of the reasons above is that the contractor wants to define their area and their efficiency (read: money) is more important than the user's (you pay taxes no matter what).

Those are some reasons why long construction zones aren't entirely wasteful. That doesn't mean that there aren't ways that they can be improved, though. The problem is that there is limited benefit to the people controlling the zones to shortening the zone length.

Answer 2

There is some merit in the argument that one mile on one mile off construction would be dangerous. Works vehicles would have to enter and exit every mile from live traffic. They'd go from 50mph to some stupid speed like 2mph and back every mile go get along the works.

I would seriously question though whether it's cheaper per se. It's easier. A lot of road jobs are rolled up into large multi year contracts /partnerships where a safety case has to be made. As part of the UK's war on the motorist, Health & Safety plays a disproportionate role in evaluation of long term contract /partnership bids. It can thus be used as a lever against the pencil heads to extract more money from them. It's really a license to print money as in the UK it's politically incorrect to challenge Health & Safety.

You're not the only one to complain about those works. They've been criticised in the House.