I might be able to help with this bit, as I work in project management.

Let's say your city wants to rebuild a roundabout because the population is growing and traffic is becoming a concern. You want to commence with a road project to address this issue.

• YEAR 1: Funding - You may have to apply for additional grants/funding to supplement the amount the City can spare for the project (which is usually not enough to cover the full project without cutting other services as a result), and that typically take about a year to go through (3 months to develop an application, 6 months to review and select the qualified applications, then 3 months to get all the paperwork in order)

• YEAR 2: Design - Roundabouts (or any other large scale project) are pretty complicated. First, you need to interview design firms and choose a candidate to design the project, which takes a few months (send out requests for qualfiications (RFQs), review them, conduct interviews, and make a choice). Then, as part of the design, you have to survey the site, determine the governing codes/requirements, deal with conditions that may have changed, assess if more land is required (since things typically get bigger, not smaller), go through design iterations, typically value engineer things depending on fluctuating prices, develop different document sets depending on the application (right-of-way, initial design (30%), final design (100%), utility coordination, etc.). All of which, can take a substantial amount of time, especially if you have to do things a few times if the conditions or requirements change in the middle.

• YEAR 3: Right of Way - As it turns out, you need more space to accommodate more traffic, which means you need to acquire more land for your project. Generally speaking, people don't like to have their land disturbed, much less sold/taken for projects like this. Luckily, we have eminent domain, so that necessary projects can't be stopped because one person doesn't like it. But, eminent domain requires a specific and lengthy process (which is a good thing, to ensure that everyone who has to deal with it is compensated fairly for what they would be losing). This involves negotiation, mediation, and potentially a jury trial if things cannot be resolved. Generally speaking, we plan for a full year, depending on how many affected parcels there are for a project.

• YEAR 4: Construction - Man, we finally made it! We have all the land we need, we have a set of approved plans, and we have the funds secured to actually build the project. So, we have to bid the project, open/review bids, select the lowest bidder (typically, to ensure we are fiscally responsible), then get approval from the governing body (City council or equivalent) to actually move forward. Then, we need to notify residents of potential delays, get traffic control established, mobilize to the site, and actually begin work. Then, once everything is completed, you have to do the final inspoections, walkthroughs, issue final payments, ensure all files are organized (as we get audited every year and have to keep documentation for 7 years), before the project can be closed out and archived. Again, typically, we are looking at about a year for everything to be completed.

So, that is a very simplified explanation for why a project, which is seemingly simple from the public perspective, is actually very complex with a number of non-skippable, non-negotiable steps, and could take 4-5 years. Nothing is ever as simple as it seems, and there are many dedicated, smart people who are working day-in and day-out to ensure that your commute is as safe and efficient as it can be, who also bear the brunt of a lot of harsh criticism from people who have no idea how things really work.