The E21 KajangâÂÂSeremban Highway, commonly known as the KASEH Highway (or LEKAS, from Lebuhraya KajangâÂÂSeremban), is a Malaysian expressway linking Kajang in Selangor to Seremban in Negeri Sembilan.
Speed limits vary along the route. Most sections permit speeds of up to , while certain stretches, such as those between Setul and Paroi, are restricted to .
The KajangâÂÂSeremban Highway has a total length of . It passes through several Malaysian towns, such as Semenyih, Pajam, Mantin, and Temiang and also connects to the Seremban Inner Ring Road. The highway redistributes traffic flow from other heavily congested expressways, including the NorthâÂÂSouth Expressway Southern Route and the Kuala LumpurâÂÂSeremban Expressway.
The highway project has progressed through multiple stages of completion:
The kilometer zero of the expressway starts from Exit 1804 of the Kajang Perdana Interchange, which connects the expressway to the E18 Kajang Dispersal Link Expressway and the Kajang Bypass near Kajang, Selangor.
The LEKAS Highway project was approved by the Malaysian government in 1997. Construction started in 2002 but faced delays due to financial challenges encountered by the original concessionaire, KajangâÂÂSeremban Highway Sdn. Bhd. (KASEH). In November 2006, the project resumed under a new concessionaire, Lebuhraya Kajang-Seremban Sdn. Bhd. (LEKAS), a joint venture between IJM Corporation Berhad and KASEH with a 50% stake held by each. It was scheduled to be completed by December 2009.
Phase 1 of the expressway, which connects Kajang South to Pajam, was opened on 23 August 2008. The main subcontractor was WCT, which then subcontracted the beam manufacturing to Mudajaya. To allow motorists to familiarize themselves with the expressway, it operated toll-free for a month.
The expressway system was extended with the opening of Mantin toll plaza on 31 December 2008. The extended route remained toll-free until 30 January 2009.
On 1 March 2010, the Setul and Ampangan interchanges opened for traffic.
On the night of 27 September 2007, at about 11:45 p.m., eight large concrete beams, each weighing close to 70 metric tonnes (around 77 short tons), collapsed at a construction site near the Pajam Interchange on the KajangâÂÂSeremban Highway. The site was about 1 kilometre (0.6 miles) from the interchange. No one was injured in the incident.
In the months that followed, the contractor built a temporary public bypass road, about 4 kilometres (2.5 miles) long, so traffic could continue to move around the construction area. The bypass linked Federal Route FT3265 to the Pajam Interchange, passed through the Pajam Toll Plaza, and rejoined the same route closer to the town of Nilai. The collapsed beams were later rebuilt and installed. All repair costs were covered by the contractor, and no public funds were used.
The affected section of road is now open to traffic and forms part of the LEKAS Highway.
On 17 April 2010, Achik Spin, a singer with the Malaysian rock band Spin, died in a car accident on the KajangâÂÂSeremban Highway near Pajam, Negeri Sembilan.
On 3 May 2020, at about 2:11 a.m., Corporal Safwan Muhammad Ismail, aged 31, died after his vehicle collided with a police COVID-19 roadblock near the Kajang Selatan toll plaza.
As part of an initiative to facilitate faster transactions at all toll plazas, all toll transactions on the KajangâÂÂSeremban Highway have been conducted electronically via Touch 'n Go cards or SmartTAG since 2 March 2016. This is the first closed toll expressway to phase out of the closed toll system.
(Since 1 January 2023)