A £780M congestion-busting roads revamp in Las Vegas is nearing completion.
In Las Vegas everything is big. The hotels, the casinos, even the water fountains. So when the Nevada Department of Transportation (NDoT) decided to revamp the city’s road infrastructure, it was no surprise that it decided to “go big”.
Nearly two decades in the making, the aptly-named Project Neon is the largest public works project in Nevada’s 150-year history. Costing just shy of $1bn (£780M), it sets out to widen 6km of motorway from the outskirts of the city to a purpose built interchange called Neon Gateway in downtown Las Vegas. In total, 19km of lane conversion across the city will be introduced to separate motorway traffic from general traffic, reducing merging and weaving of traffic.
Busiest Nevada highway
The project’s aim is to reduce congestion on Interstate 15 (I-15) and Highway US 95 (US 95). This stretch of the I-15 is the busiest highway in Nevada, handling 300,000 vehicles daily, making 25,000 lane changes per hour. Traffic through the corridor is expected to double by 2035. When Project Neon is complete, traffic delays are expected to be reduced by 28%.
The project involves construction of 29 new or replacement bridges, the largest of which is a 764m long high occupancy vehicle (HOV) flyover which connects US 95 with the I-15, creating 35.4km of continuous carpool and rapid use lanes. The project will also create carpool access l ramps, reconstruct Charleston Boulevard interchange – a major connection to Las Vegas Boulevard and downtown – and extend Grand Central Parkway over the Union Pacific railway tracks.
Major sections of the new 25m tall flyover were finished in November 2018 – two months ahead of schedule – representing a major milestone for project partners contractor Kiewit and consultant Atkins as the project ramps up for a July finish. With the entire project 88% complete, four of the new flyover’s bridge spans are left to install on the new flyover, together with some local roadworks and final traffic management systems installation.
“The last sections to put in will actually be suspended right over the I-15,” says Kiewit information officer Jay Proskovec. “One of the limitations of the project specification was that we couldn’t take more than one to two lanes of freeway anywhere along the route for any significant amount of time,” he says. “So we have had to be pretty inventive with the design to figure out the order in which we were building things, as well as building as much as possible away from the freeway.”
Atkins project manager Mike Warnick adds: “We have seen 34 major traffic switches to date and there are about 13 left, so we will have done 47 in total by the time of completion. That was a big part of our design phase in order to keep traffic flowing as well reducing costs by reducing temporary works needed for big switches.”
Similar structures save time
“Likewise with the bridge structures, we have managed to save a lot of time by keeping them pretty similar in order to simplify construction,” he says.
“They are all concrete beam girders, or concrete box beam girders. We have used precast girders, precast bridge deck panels and California wide-flange, precast beams [similar to a concrete I-beam] because we could make them longer spans, thereby eliminating the need for more columns.
“The combination of the three has allowed for an accelerated pace, so we could build a bridge span within 30 to 45 days. So that really shaved a lot of time off building the bridge.”
And the ability to get work done on time, or even ahead of schedule was integral to Kiewit Infrastructure West being appointed the general contractor under a $559M (£442M) design and build contract, with Atkins acting as lead designer.
Bridge 936 c 180420
The team’s design proposal reduced construction programme estimates by 300 days, giving the project a time-cost saving of around $80M (£63M). This was largely achieved by tweaking the positioning of the flyover shortening it from 1.43km to 792m. This reduced construction time by four months.
“During the bidding phase, we came up with an alternative that saved a large portion of bridge by tweaking the bridge structure and the location, which saved time and cost for everybody,” Warnick adds.
“We have either met or come in ahead of schedule on every interim milestone to date. The [US]95 work was 54 days ahead, the I-15 work was 12 days ahead. So, the next one is the final push to be done before mid-July.”
Indeed, the team won a £3.9M bonus for reopening a lane of US95 in each direction two months early. Dubbed ‘‘the Big Squeeze’’ workers were on site seven days a week to make room for the signature HOV.
Bonuses for early completion
Incentivising the contractors is a big part of NDoT’s project delivery strategy. Atkins and Kiewit stand to earn up to nearly £16M together in early completion bonuses. But if they come in late there are liquidated damages, with penalties imposed with each hour the project is delayed.
“We have had a lot of crews working five, six, days a week running days shift, night shifts and swing shifts from March until November,” Warnick adds. “Sometimes seven days a week during the critical times. It is nice to be through that phase now and take our foot off the gas a bit now.”
Off-site manufacturing and prefabrication has helped cut a significant amount of time out of the construction schedule. Eight concrete girders used on the HOV flyover were prefabricated almost 500km away in Phoenix, Arizona and required a 16-car police escort to transport them to site. Likewise, the deck panels were made offsite. The project’s 42 active traffic management (ATM) boards were created by Daktronics, while their steel support structures were shipped in from North Dakota.
Health and safety push
The ATM system is part of a wider push to improve safety on the route. With around three car accidents a day on the I-15, NDoT is confident that widening the route and introducing new carpool lanes will reduce the number of unnecessary lane changes, resulting in fewer accidents. In total, 42 ATM boards will be installed at 800m intervals along the route, including a 23m long gantry that will be the longest sign structure in the state.
“This will be one of the first value-wide active traffic management systems in the US,” NDoT information officer Tony Illia says.
“Other places have sporadic signs but this is one of the first to introduce ATM signs every half mile. Places have these signs but nowhere near as immense as this, spanning the entire road way. A lot of other places are looking at how this system works and are excited to see it in action.”
Technology on the project is not limited to the traffic management systems. To “sell the project” to the public, Warnick explains how Atkins turned its CAD drawings into a virtual reality driving simulator.
Warnick adds: “Being able to put people in the driving seat through the animation made from our CAD drawings was a great benefit to get the public on board,” Warnick says.
“We also created a virtual helicopter tour that flies to the south of the project and does the whole route and then lands back at our central office. We used both at public meetings and it was crucial to getting the public buy in.”